(PDF) A Revision of Borassus L. (Arecaceae)

A Revision of Borassus L. (Arecaceae)

Author(s): R. P. Bayton

Source:

Kew Bulletin,

Vol. 62, No. 4 (2007), pp. 561-585

Published by: Springer on behalf of Royal Botanic Gardens, Kew

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KEW BULLETIN 62: 561-586 (2007) 561

A revision of

Borassus

L.

(Arecaceae)

R P.

Baytoni

Summary. A taxonomic revision of the genus Borassus L. (Arecaceae: Coryphoideae.

Borasseae) is

presented. Five

species are recognised: B. aethiopum

from Africa and Madagascar, B. akeassii from West and Central Africa, B.

madagascariensis from Madagascar, B. flabellifer

from

South and Southeast Asia and B. heineanus from

New Guinea.

Pollen morphology and leaf anatomy are examined and the taxonomic history,

morphology, distribution,

ecology and conservation stattus

are discussed.

Key words. Borasseae, Coryphoideae,

anatomy, morphology, palm, pollen, taxonomy.

Introduction

Borassus L. of subfamily Coryphoideae, tribe

Borasseae,

subtribe Lataniinae (Dransfield et

al. 2005), is

one of

the

most widespread genera in the

Arecaceae with a

distribution encompassing tropical Africa and

Madagascar, southern and Southeast Asia and New

Guinea (Map 1). A phylogenetic study

using nuclear

and chloroplast DNA sequences (Bayton 2005),

suggests that

Borassus is monophyletic in its

current

circumscription, but further commentary will be

reserved for

a future

publication.

Throughout its range,

Borassus (and particularly the

Asian palmyrah, B. fiabellifer

L.) provide a huge variety

of products of great significance to local economies.

Every part of the palm is utilised, though perhaps the

most significant

product is the sweet sap (toddy,

Tamil)

extracted by tapping the

stem

or inflorescences. This is

fermented into palm wine (arrack, derived from

Arabic) or, the crude sugar (jaggery,

derived from

Portuguese) is crystallised (Morton 1988). It is

not the

intention of this account to review the current and

potential uses of Borassus and several such works

already exist (e.g. Blatter 1912; Porteres 1964; Fox

1977; Kovoor 1983; Davis & Johnson 1987; Morton

1988; Burkill, 1997). However, it is noteworthy that

despite its

economic significance, the taxonomy of

Borassus has remained problematic. Species

delimitation in

Borassus has always been challenging.

Borassus palms are

massive, with

huge stems

of up to

20

m tall and 1

m diameter, which makes gaining access

into the crown challenging. The leaves and

inflorescences are very large and consequently only

small parts can be collected, while essential

accompanying notes are often absent. The process of

collecting, doctumenting and preserving herbarium

specimens is extremely time-consuming. Therefore

there is a dearth of herbarium material. Existing

material is often incomplete with juvenile leaves

substituted for the inaccessible mature leaves. In

addition, all Borassus species are dioecious, decreasing

further the comparability of existing specimens.

Species delimitation in Borassus has relied upon

morphological characters that reflect the narrow range

of available herbarium material, or that can only be

determined in the field.

An additional problem with

Borassus is missing type specimens. Of the seven

species recognised in the most recent taxonomic

revision of the genus (Beccari, 1924), only three have

extant type

specimens (a fourth is lectotypified

with

an illustration,

Moore & Dransfield 1979).

Taxonomic

History

Borassus and the type species B. flabellifer

were

described by Rheede tot Draakestein (1678) in the

Hortus VWalabaficis

under the names Ampana (staminate

palm) and Carimpana (pistillate palm). The description

of B. flabellifer

by Linnaeus (1753) cites Rheede's

account (among others), and the accompanying

illustrations have since been selected as the lectotype

(Moore & Dransfield 1979). Borassus in

Africa was

considered by some authors to

be only a variety

of B.

flabellifer (Kirk 1867; Warburg 1895; Drude 1896,

Dammer 1901), but a second species, B. aethiopum

Mart. was described by

Martius (1838). The debate over

whether or not to

recognise Borassus aethiopum

is

largely

Accepted for publication November 2006.

1

Centre for

Plant Diversity & Systematics, School of Biological Sciences, The University

of

Reading, P0 Box 221, Reading, Berkshire,

RG6 6AS, U.K. and

Herbarium, Royal Botanic Gardens, Kew, Richmond, Surrey, TW9 3AB, U.K.

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562 KEW BULLETIN VOL. 62(s)

resolved, with most recent authors accepting both

species (Beccari 1914, 1924; Kovoor 1983; Dransfield

1986a). A limited molecular study by Kovoor &

Hussein (1983) came to the same conclusion.

The taxonomy of the two endemic Borassus species

in Madagascar has received recent attention

(Dransfield & Beentje 1995a; Bayton et al. 2003).

Borassus madagascariensis (Jum.

& H. Perrier) Bojer ex

JLIm.

& H. Perrier was first

published in 1837i in a

catalogue of the native and exotic plants of

Mauritius

(Bojer 1837). Bojer stated that the

palm was. native to

Madagascar and could be found in the vicinity of

Majungay (now Mahajanga), and also in the Royal

Botanic Gardens of Pamplemousses (now the Sir

Seewoosagur Ramgoolam Botanical Gardens) in

Mauritius. Bojer's account does not include a

description of B. madagascariensis and his name is

therefore a nomina nuda. Jumelle and Perrier de la

Bathie (1907) accepted Bojer's account, but reduced

the species to a variety of B. flabellifer.

They later

(1913) elevated it to specific rank and it is their

accounts that inadvertently validate the epithet at

both varietal and specific ranks. A second species of

Barassus was also described byjumelle and Perrier de

la Bathie (1913). Borassus sambiranensis Jum. & H.

Perrier is restricted to the

Sambirano Region in the

northwest of the island. In the most recent taxonomic

treatment of the

Madagascar palms, Dransfield and

Beentje (1995a) concluded that there were few

morphological characters to

distinguish the endemic

Borassus species, either from each other or from B.

aethiopum in

mainland Africa.

In 1914, Beccari published the first taxonomic

revision of Borassus. In it, he described three neNw

species, and two

new varieties of B. aethiopum.

He also

transferred Borassus machadonis Ridl. into the new

genus Borassodendron Becc. (Beccari 1914). This

account was later expanded to include the other

borassoid genera and was re-published after Beccari's

death (Beccari 1924). Beccari's treatments recognised

Borassus flabellifer as restricted to

Asia and added

Borassus sundaicus Becc. from Indonesia and Borassus

heineanus

Becc. from New Guinea. The latter species is

morphologically divergent from other Borassus

species, and in some ways resembles Borassodendron

machadonis (Ridl.) Becc. (Beccari 1924).

In Africa, Beccari described B. deleb Becc. from

Sudan and recognised three varieties of Borassus

aethiopum: var. senegalensis Becc. in WVest Africa,

typified by material from modern-day Mali, var.

bagamojensis Becc. in East Africa, based on material

from

mainland Tanzania and var. aethiopum from

Central Africa (though the type

was from

Ghana).

Chlevalier described a fourth variety,

var. domesticus

A.

Chev., from

material collected in

Mali (Chevalier &

Dubois 1938). However, this name is not valid as

there was no Latin

diagnosis. In his treatment

of the

East African palmus,

Dransfield (1986a) reducect all

African taxa to a single species, with B. deleb

and the

varieties in synonymy.

However in 1996, Ake Assi &

Guinko (1996) examined a Borassus palm from

West

Africa that was morphologically distinctive. Further

details were provided by Ouedraogo et

al. (2002) and

Arbonnier (2002) and the consensus of opinion was

that these palms represented B. flabellifer,

previously

unknown in

Africa. However, this taxon was later

recognised as a newv species, B. akeassii Bayton,

Ouedraogo & Guinko (Bayton et

al. 2006).

Morphology

Stem & Habit

All Borassus species have a large single stem,

branching only when damage has occurred

(Ramassamv & Kannabiran 1991). The stem is

clothed in dead leaf bases, though these later abscise

cleanly leaving prominent scars. The stem of the

African and Madagascar species is

uisually

ventricose

with a prominent swelling below the crown. The

anatomy and adaptive significance of this swelling

has not been investigated, but Tuley (1995) and

Henderson (2002) suggest that it is

an adaptation to

arid environments (though ventricose stems are not

exclusive to palms from arid habitats); Barot &

Gignoux (1999) proposed that it is

connected with

the

onset of sexual maturity. Field observation of this

character indicates that

within a population, the

swelling is usually at a similar height in each tree,

and multiple swvellings

have been observed in some

individuals (Tuley 1995). Ventricose stems are

characteristic of a number of unrelated palm genera,

many of which occur in seasonally dry habitats.

When the

ventricose stem of

Acrocomia crspa (Kunth)

C. F.

Baker ex Becc. (syn. Gastrococos crispa (Kunth)

H. E. Moore) wvas examined, the cells within were

found to

have extremely high water content (Fisher

et

al. 1996).

Leaves

The leaves are costapalmate; the lamina is

split to one

third

or half of its

radius, with up to 130 induplicate

leaflets. There is a prominent triangular cleft in the

sheath below the petiole. Towards the stem, the leaf

sheath disintegrates, forming a network of tough,

woody fibres.

The petiole is robust with a flat adaxial

surface and a rounded abaxial surface; the

margins

can be armed with spines or unarmed. There is

considerable variation in the density, shape, size and

colour of the spines, which are influenced by light

intensity and the age of the plant (Fig. 1). Adaxial

and abaxial hastulae are usually present at the

juncture of the petiole and lamina. The lamina is

broad, undulating anld stiff

towards the base.

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A REVISION

OF BORASSUS L.

(ARECACEAE) 563

InduLnentum may be present on the costa and leaf

fold ridges of both surfaces, though it erodes in older

leaves. The transverse commissural veins, which link

the

major parallel veins of the leaf, are distinct and

their spacing varies significantly from species to

species. The leaflet apices may be acute or cuspidate,

bifid or entire.

Leaf Anatomy

The anatomy of palm leaves was examined by

Tomlinson (1961), who noted that in the Borasseae,

there was an unusually high incidence of isolateral

leaf symmetry. Most palms have leaves with an

asymmetrical (dorsiventral) anatomy i.e. a well

defined adaxial palisade mesophyll, and stomata

primarily on the abaxial surface. However, most

Borassus species lack a clearly defined palisade, and

have stomata on both surfaces, i.e. isolateral anatomy

(Tomlinson 1961). Leaf symmetry is thouLght to

be

correlated with light exposure (Tomlinson 1961)

and/or aridity (Barrow 1998). In the Borasseae,

genera from exposed or arid habitats (Bismarckia

Hildebr. & H. WVendl.,

Hyphaene

Gaertn. and Medemia

Wurttenb. ex H. Wendl.) exhibit isolateral leaf

symmetry, while those from shady, humid habitats

(Borassodendron, Lodoicea Comm. ex DC. and

SatranalaJ. Dransf. & Beentje) show dorsiventral leaf

symmetry. Latania Comm. ex Juss.,

a genus of coastal

cliffs

and savannas, has a somewhat intermediate leaf

anatomy (Tomlinson 1961). Borassus reflects this

overall pattern as most species of this primarily arid

zone palm have isolateral leaf symmetry, but B.

heineanus, from the rain forests of

New Guinea, has

dorsiventral leaf anatomy.

I a I.

3 cm

Fig. 1. Borassus petiole margin armature. A Borassus heineanus

(Papua

New

Guinea),

Banka s.n. (K);

B

B. flabellifer

(Thailand),

Wilkin

et

al. 1

160 (K); C B.

madagascariensis

(Madagascar), Bayton

& Ranaivojaona

51 (K);

D B.

aethiopum (Madagascar), Bayton

& Ranaivojaona

53 (K);

E B.

aethiopum (juv., Kenya), Bayton

& Obunyali

14 (K);

F

B. aethiopum (Kenya),

Dransfield

4811 (K);

G B.

akeassii

(juv.,

Burkina

Faso), Bayton

et al.

72 (K);

H B.

akeassii (Burkina

Faso), Bayton

et al.

74 (K). DRAWN

BY

LUCY

T.

SMITH.

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Royal

Botanic Gardens, Kew, 2007

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564 KEW BULLETIN VOL. 62(4)

Inflorescences

Borassus is pleonanthic and dioecious though

monoecy occurs rarely as a monstrosity (Louis &

Mary 1975). The inflorescences are axillary, shorter

than the leaves and the staminate and pistillate forms

are superficially dissimilar. The prophyll is the first

bract on the inflorescence and is large, bicarinate

and coriaceous, however it is rarely collected duLe to

its position deep within the leaf axils. NuLmerous

large, primary bracts sheath the inflorescence, and

these are largely indistinguishable from the

prophyll.

They often have hard, woody apices, fibrous margins

and green longitudinal stripes. Staminate

inflorescences are usually branched to one or two

orders (Figs 3E, 5E), but pistillate inflorescences are

typically spicate (Figs 4A, 5G).

The first-order branches of the staminate

inflorescence terminate in 1

- 3(- 5) rachillae that

are covered in scale-like rachilla bracts (Figs 3E, 5F).

These bracts are imbricate and partially connate and

consequently, the rachillae resemble massive catkins.

In the axil of each scale is a cincinnus (Fig. 3H)

containing several staminate flowers that are

obscured in a pit formed by the bracts (Figs 3F - G).

Each flower is

exserted from its pit sequentia'ly, by

elongation of the floral receptacle. Pistillate

inflorescences of most Borassus species are typically

spicate, though branching is

common in

B. akeassii

(Fig. 5H), perhaps due to human-inflicted damage

(Bayton et

al. 2006). The flower-bearing portion of

the pistillate inflorescence is covered with large

cupular bracts. The first few bracts are empty, but

subsequent bracts subtend pistillate flowers.

Unlike

the staminate flowers, pistillate flowers are solitary

and superficial on the rachis.

Flowers

The staminate and pistillate flowers are widely

divergent. Staminate flowers (Fig. 3J

- K) are less

than a centimetre long and are subtended by

membranous bracteoles. The calyx is angular and

membranous with three lobes. The receptacle and

corolla are fused for

most of the length of the flower,

though there are three small, keeled corolla lobes.

There are six stamens with very short triangular

filaments and medifixed, latrorse anthers. A

pistillode of varying size is usually present. The

pistillate flowers (Fig. 4A - B) are solitary and much

larger than the staminate flowers (approximately 2 x

3 cm). They are subtended by coriaceous bracteoles,

and have three distinct imbricate sepals and three

distinct imbricate petals. A staminodal ring is

usually

present. The ovary is tricarpellate with basal septal

nectaries and the three stigmatic areas are

superficial on the apex.

Fruits and

Seeds

The fruits (Fig. 4D) are very large (uLp

to

35 cm long)

with a coriaceoLls epicarp, wvhich varies in colour

from

green to

orange to black. The sepals and petals

remain attached to the rachis and persist around the

base of the developing fruit up to and incltuding

maturity. The mesocarp is pulpy and fragrant,

containing many longitudinal fibres. There is a

separate endocarp surrounding the locule of each

carpel, and this

encloses the seed forming a pyrene

(Figs 4E - H). There are between one and three

pyrenes in each fruit

and the number of pyrenes in

the fruit has an impact on the shape and size of both

the fruit

and the pyrenes (Fig. 4C). The pyrenes are

woody and are often fibrous, and there is

a great deal

of variation in shape, size and ornamentation. Some

pyrenes are bilobed and may have a deep

longitudinal furrow that can penetrate the seed

within (Fig. 4E). Other pyrenes have a prominent

external crest, the vestigial remains of the link

between the endocarps, wvhich divided duLring

development. In some specimens of B. heineanus,

there are internal flanges of the endocarp that

penetrate the seed, though these are invisible

externally (Fig. 4H). The seed almost entirely fills the

endocarp cavity; the endosperm is

homogeneouls and

bony and there is

a small central hollow. Germination

is remote-tubular, and the cotyledonary petiole

rapidly extends, penetrating the soil. The embryo is,

in effect, buried underground where it is safe from

herbivory and small fires (Tuley 1995; Barot &

Gignoux 1999).

Pollen

Ferguson et

al. (1986) examined the

pollen of seven

of the eight genera of tribe Borasseae and incltuded

Borassus fiabellifer

and B. aethiopum. The eighth genus

Satranala was discovered later (Dransfield & Beentje

1995b) and its

pollen has since been examined (M.

Harley, pers. comm.). Borassoid pollen is in

general,

monosulcate, tectate and either elliptical or

subcircular in polar view. The aperture is

almost as

long as the longest axis in

polar view (L), though in

Borassodendron it is

onlv a quarter of the length of L.

Supratectal gemmae are present in

Borassus (Fig. 2)

and Ilyphaene (Ferguson et

al. 1986). Slight differences

between the pollen of Borassus flabellifer

and B.

aethiopum

were noted; the gemmae of B. aethiopuum

were variable in size and a dense band of small

gemmae surrounded the aperture. In B. flabellifer

the

gemmae were of two

distinct sizes and the aperture

margins wvere

smooth (FerguLson

et

al. 1986). However,

the small sample size (one specimen per taxon)

probably precludes meaningful conclusions.

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A REVISION

OF BORASSUS

L. (ARECACEAE) 565

t~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

~.

_

rm S9~~

EX~~~~~~~~~~~~~~~~~~~~~~~~~~0

Fig. 2. Scanning

electron

micrographs

of Borassus

pollen.

A B. aethiopum

(Burkina

Faso),

Bayton & Ouedraogo 59 (K); B 8.

aethiopum

(Sudan),

Brown & Brown s.n.

(K); C B. flabellifer

(Indonesia),

fox s.n. (BH);

D 8.

akeassii (Burkina

faso),

Bayton

et

al.

74 (K);

E B. flabellifer

(Sri

Lanka),

Zoysa 49 (K); F B.

akeassii

(Burkina

Faso),

Bayton

et al. 74 (K);

G B. heineanus

(Papua

New

Guinea),

Ferrero 424 (AAU);

H B.

madagascariensis

(Madagascar),

Bayton

& Ranaivojaona

46 (K).

Scale bars

for A, B, E - H = 20 pm;

C - D = 10 pm.

C The

Board of Trustees

of the

Royal Botanic Gardens,

Kew, 2007

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566 KEW BULLETIN VOL. 62(4)

Distribution

and Ecology

Distribution

A distribution map for Borassus, based on point

locality data extracted from

herbarium specimens, is

provided (Map 1). Borassus is one of the

world's most

widely distributed palm genera, challenged only

perhaps by

Calamus L., Phoenix L. or Livistona R. Br. It

occurs across the Old World tropics, but is absent

from the

Americas, except in cultivation (Morton

1988). Identifying the natural distribution of the

palm is

however difficult, due to its long history of

cultivation. Countries on the

margins of the present

distribution (e.g. Australia, Cape Verde) often have

isolated Borassus populations of unknown origin.

Moreover, some seemingly wild populations may

actually represent 'feral' crop plants. Therefore a

broad and inclusive concept of the natural

distribution of Borassus, at least in the Old World

tropics, has been accepted here.

In Africa, Borassus is restricted to the sub-Saharan

region, but is absent from large parts of the central

African rain forests, from the arid southwest and

from the Horn of

Africa. The southern limit of its

distribution is in northern South Africa. There are

several African countries where floristic data are

limited and so the presence of Borassus cannot be

determined (e.g. Angola, Burundi, Congo

Brazzaville, Liberia). Borassus has been collected on

the arid island of Soqotra, though it is probably

introduced (Miller & Morris 2004). Other African

islands where Borassus has been recorded include

Sao Tome (Exell 1944; 1973), Bioko (Guinea Lopez

1946), Cape Verde (Chevalier 1935, Henderson et

al. 2003), Pemba (Dransfield 1986a), Zanzibar

(Beentje 1990) and Mayotte (Ludwig 1999; Pascal &

Labat 2002). In

Madagascar, Borassus is restricted to

the western part of the island, and has been

recorded on the offshore islands of Nosy Be

(Bayton et al. 2003) and Nosy Mitsiou (Dransfield &

Beentje 1995a).

In Asia, Borassus flabellifer

occurs across the Indian

Subcontinent (including Sri Lanka) through

Myanmar into Indochina. Borassus occurs in China

(Yunnan), Pakistan and Peninsular Malaysia, though

is reported to have been introduced to these

countries (Whitmore 1973; Malik 1984; Pei 1991). In

Indonesia, Borassus has been recorded across the

archipelago, though excluding wetter areas such as

Borneo and the northern Moluccas. On New

Guinea, Borassus heineanus is restricted to the

northern part of the island, and is found in both

0 10002 030004000 Kilometers

Map 1. Distribution of

Borassus, based on point locality

data extracted

from

herbarium

specimens.

A B. aethiopum;

0 B. akeassii; i B.

flabellifer;

* B. heineanus;

0 B.

madagascariensis.

Map prepared by

Justin Moat, GIS Unit, Royal Botanic Gardens,

Kew.

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A REVISION OF BORASSUS

L. (ARECACEAE) 567

Papua New Gulinea and Indonesian Paptia. A few

specimens of Borassus have been found in northern

Queensland, Australia (Bailey 1902), but they are

probably not native (Jones 1984).

Ecology

Borassus species occur in a variety

of habitats. Borassus

heineanus grows on alluvial sands in the tropical rain

forests of New Guinea (Barfod et al. 2001). The other

Borassus species are typical of seasonally dry open

areas with wet soils. In Africa, they are found in

mixed riverine forest where they may or may not be

the dominant species. Borassus aethiopum

can form an

almost continuous closed-canopy forest

or individuals

can be widely spaced forming distinctive palm

savannas (Tuley 1995). The accessibility of many B.

aethiopum populations and the easily-identifiable life

stages, have made the species a popular subject for

studies of population dynamics (Mordelet et

al. 1996;

Barot et al. 1999a, 1999b, 2000; Barot & Gignoux

1999; 2003). In Madagascar, Borassus exists almost

entirely in conjunction with human settlements

(Bayton et

al. 2003), though perhaps this is the result

of a shared preference for alluvial soil. In India, B.

flabellifer

is characteristic of sandy plains and savanna

(often near the sea), and secondary forest up to

800

metres altitude (Davis & Johnson 1987;

Sankaralingham & Hameed Khan 2001). On the

Indonesian island of Madura, Borassus also favours

dry sandy areas (Dransfield 1976). In many Asian

countries, Borassus is a common and familiar sight

lining the margins of rice paddies.

There are no published studies of pollination in

Borassus (Henderson 1986), though Bayton et al.

(2003) noted that

honey bees (Apis

mellifera)

were the

main visitors to the staminate flowers of B.

madagascariensis. Animal-mediated seed dispersal

(zoochory) in palms was reviewed by Zona and

Henderson (1989) and while there have been few

studies that included Borassus, the range of animals

implicated is impressive.

These include bats (Mtarshall

& McWilliam 1982; Marshall 1983, 1985), lions

(Dransfield 1986a), baboons (Lieberman et

al. 1979),

and African elephants (Burtt

& Salisbury 1929). While

all of these animals are known to feed on the fruit,

only in the case of elephants has effective dispersal

been demonstrated (Burtt

& Salisbury 1929). In some

areas, the

weight of the fruit

alone is the

only

method

of dispersal (barochory) (Barot et

al. 1999b).

Methods

Taxonomy & Nomenclature

In this

paper, a revision of Borassus is presented, based

on herbarium material from the following institutions:

AAU, BH, CANB, fl-G, K, NY and P. Additional

material was examined in

situt

at the following

herbaria:

BM, EA, OUA and TAN. Photographs of tpe material

and other Borassius specimens from the Beccari

collection at Fl were made available by W. J. Baker and

J. Dransfield. To supplement the existing specimens,

three fieldtrips were organised: Kenya (October,

2002), Madagascar (March, 2003) and Burkina Faso

(January, 2004). Herbarium material was collected

using the modified Schweinfurth process (Dransfield,

1986b). Staminate and pistillate specimens were

collected separately with accompanying vegetati-ve

material. Access to the

crowvn

was provided by use of an

extendable pole Nwith

attached pruning saw. Extensive

notes were recorded for each specimen as only small

parts

were saved for the

herbarium. In Kenya, all of the

fruits

from three felled pistillate palms were measured

to ascertain the range of variation in fruit size. In

Burkina Faso, a sample of one hundred pistillate palms

was examined for evidence of branching in the

inflorescence. Several photographs (deposited in the

palm slide collection at K) were taken of each palm

including images of the

palm in habitat and images of

the

various perishable characters such as petiole and

fruit colour. Preliminary conservation status

assessments are provided folloNving IUCN guidelines

(IUCN 2001).

Pollen

Ferguson et

al. (1986) examined the pollen of the

palms of tribe Borasseae and noted some differences

between Borassus flabellifer

and B. aethiopum. In an

effort to confirm these findings and identify

other

significant interspecific pollen characters, multiple

pollen samples were collected from all species. The

pollen was extracted from the anthers of staminate

flowers that wvere removed from herbarium

specimens, or wvere collected directly in the field.

Field-collected staminate flowers

were dried in silica

gel. The pollen was acetolysed according to the

method of Erdtman (1969). For comparative

purposes, unacetolysed pollen was also examined.

The pollen was examined using both a Reichert

Polyvar 2 light microscope and a Hitachi S-2400

scanning electron microscope. Pollen terminology

follows Punt et

al. (1994).

Leaf Anatomy

The leaf anatomy of Borassus was examined by

Tomlinson (1961), but only two

of the five

species (B.

aethiopum and B. flabellifer)

were examined. Leaf

material for anatomical study was removed from

herbarium specimens. Where possible, a single leaflet

of a similar size was used for all anatomical studies.

Square pieces of leaf approximately 1 cm2 were

sectioned (both transversely

and longitudinally) to

40

pm thickness using a sliding microtome. The

sections

were stained

using

Alcian blue and

safranin,

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568 KEW BULLETIN VOL. 62(4)

and were nmounted in glycerol. The sections were

examined using a Reichert Polyvar 2 light

microscope. To clear the leaves, sections that

encompassed the whole width of one leaflet were

placed in glass dishes and covered with 5% sodium

hydroxide. The dishes were partially covered using

'cling-film' and heated in a microwave oven at full

power for five seconds. The five-second heating

periods were repeated until the leaf sections became

partially discoloured. The sections were then left in

fresh NaOH until completely discoloured. The

NaOH was then replaced with 90% bleach; when the

section was transparent, the bleach was removed and

the sections were then transferred into 30% alcohol

before being stained with safranin. The sections were

transferred into absolute alcohol via a gradient of

alcohols, and were then placed in Histoclear. The

thick midrib was removed as it prevented the

placement of a cover slip. The cleared leaflet

sections were mounted in

Canada balsam. The leaf

clearing protocol is a modified version of the

method of

Radford et

al. (1974).

Taxonomic

Treatment

Borassus L. (1753: 1183). Roxburgh (1795 - 98: 50);

Martius (1838: 219); Kunth (1841: 221); Griffith

(1851: 167); Miquel (1855: 45); Brandis (1874: 544);

Kurz (1877: 529); Bentham & Hooker (1883: 939);

Drude (1887: 40); Beccari & Hooker (1893: 481);

Baillon (1895: 255, 322); Bailey (1902: 1686); Blatter

(1912: 930); Beccari (1914: 294; 1924: 2); Backer &

Bakhuizen van den Brink (1968: 176); Malik (1984:

5); Dransfield (1986a: 18); Uhl & Dransfield (1987:

222); Pei (1991: 45); Dransfield & Beentje (1995: 51);

Dransfield & Uhl (1998: 335); Zoysa (2000: 48). Type

species: B. flabellifer

L.

Lontarus Adans. (1763: 25). Type species: L. domestica

Gaertn.

Massive, solitary, dioecious, pleonanthic tree palms.

Stem grey with well-defined leaf scars, base often

enlarged; stem ventricose with 1 to several swollen

sections below the crown, or not ventricose;

branching occasionally when damaged. Leaves

costapalmate, between 16 and 28 in the crown,

remaining attached to the stem in juvenile

specimens, then abscising cleanly in adulthood; leaf

sheath short and indistinct from the petiole,

splitting longitudinally to form a triangular cleft;

petiole robust, armed or unarmed, petiole colour

varying from green to yellow or black; adaxial

hastula distinct at the junction of the petiole and

lamina, rudimentary abaxial hastula present or

absent; adaxial and abaxial indumentum on some

juvenile leaves, confined to the ribs; leaflets

indtiplicate, apices bifid or entire, aculte or

cuspidate; commissuLral veins noticeable,

particularly in dried material, leaf anatomy

isolateral or dorsiventral. Staminate inflorescences

axillary, interfoliar and shorter than the leaves,

branched to

one or two orders, extended peduncle

bearing a coriaceous bicarinate prophyll;

peduncular bracts absent; rachis bracts yellow-green

with green striae, loNver rachis bracts similar to

prophyll, partial inflorescences borne in the axil of

rachis bracts, upper subtending branches

terminating in 1

- 3(- 5) rachillae; rachillae green

to

brown and catkin-like, covered in imbricate scale

like rachilla bracts, bracts forming pits containing a

cincinnus of 6 or more staminate flowers. Pistillate

inflorescences

axillary, interfoliar, pendulous, either

spicate or branched to one order; prophyll

coriaceous with a hard acuminate apex; peduncle

generally short, but sometimes extended with

several empty bracts, similar in form to the

prophyll; flower-bearing portion densely covered in

large imbricate, cutpular bracts. Staminate flowers

exserted from the pits in succession by elongation

of the floral receptacle; flowers exserted

individually or, rarely in

groups, each subtended by

membranous bracteoles; calyx membranous and

shallowly or deeply divided into three sepals,

corolla and receptacle fused for

most of the length

of the flower,

distally with three free cucullate petal

lobes; stamens 6

wvith

very short filaments, fused to

the receptacle, anthers erect, dorsifixed, latrorse;

pistillode present, small or large. Pollen

monosulcate and elliptical; longest axis in polar

view (L) 46 - 95 pm, polar axis in equatorial view

(h) 30 - 89 pim; aperture slightly shorter than the

grain (37 - 95 pim). Pistillate fowers large, solitary

and superficial on the rachis; subtended by two

large bracteoles; sepals (x 3) and petals (x 3)

similar, coriaceous and imbricate; staminodal ring

with 6 teeth usually present; ovary tricarpellate with

basal locules and orthotropous ovules, surmounted

by three stigmatic areas, septal nectaries basal.

Fruits massive and fragrant; mature fruits

may be

yellow, orange, red, green or black, produced inside

persistent perianth segments; epicarp coriaceous,

mesocarp pulpy, filled with longitudinal fibres,

endocarp woody and fibrous; pvrenes 1

- 3, pyrene

length equalling breadth or much longer than

wide, sometimes bilobed, some pyrenes have a

prominent dorsal crest, while others have

longitudinal furrows that can penetrate the seed;

additional internal flanges sometimes present in B.

heineanus. Seed closely adhering to the endocarp,

endosperm homogeneous and bony with a small

central space; embryo apical. Germination remote

tubular with a simple eophyll. n = 18 in B. flabellifer

( Read 1966;

Rang,asamy

& Devasahayam

1971) .

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A REVISION OF BORASSUS L. (ARECACEAE) 569

There is minimal intra-specific variation in Borassus

pollen (Fig. 2) and only B. akeassii deviates significantly

from the norm. In that species, the tectum is reticulate

and the supratectal gemmae densely cover the

surface,

all but obscuring the tectum. The differences between

B. aethiopum and B. flabellifer

noted by Ferguson et al.

(1986) do not hold up to scrutiny when pollen from

a

larger sample of specimens is examined.

The generic name Borassus was considered

Inasculine by Linnaeus (1753) as evidenced by his use

of the masculine epithet 'flabellier'.

However, Beccari

(1914) published several new names in the genus,

including B. heinieanus,

with feminine epithets ('B.

heineana'). This error was corrected recently by

Govaerts & Dransfield (2005), but uncorrected

epithets are common in the literature.

Key to the species of Borassus

1. Stem not ventricose; petiole unarmed; leaflet apices bifid and cuspidate; lamina anatomy

dorsiventral; staminate inflorescence branched to one order; pistillate inflorescence spicate;

pistillode 0.2 - 0.5 cm long; pyrene internal flanges present or absent; New Guinea

. 1. B. heineanus

1. Stem ventricose (African species) or not (Asian species); petiole armed wvith

spines; leaflet

apices acute and entire, or splitting longitudinally with age; lamina anatomy isolateral;

staminate inflorescence branched to two

orders; pistillate inflorescence spicate or branched;

pistillode 0.01 - 0.03 cm long; pyrene internal flanges absent ................................ 2

2. Transverse commissures widely spaced (5

- 7 per cm); pistillate rachis long (? 80 cm); pollen

tectum reticulate and densely covered in gemmae; West & Central Africa . 3. B. akeassii

2. Transverse commissures closely spaced (10 - 14 per cm); pistillate rachis shorter (23 - 62 cm),

pollen tectum perforate and sparsely covered in

gemmae ................................... 3

3. Stem not ventricose; fruits black; South and Southeast Asia . 2. B. flabellifer

3. Stem ventricose; fruits green, yellow or orange; Africa & Madagascar ............................ 4

4. Petiole green along whole length, spines very snmall

(0.1 - 0.85 cm long) and pointed; fruits

green, with pointed apices; pyrenes very large (8 - 12 x 8 - 12 cm); MLadagascar * * 5. B. madagascariensis

4. Petiole black or yellow-black, spines large (0.4 - 2.8 cm long) and recurved; fruits

yellow

orange or red, with flattened or depressed apices; pyrenes large (6 - 10 x 5

- 8 cm); Africa &

Madagascar ..........................................................*4. B. aethiopum

1. Borassus heineanus Becc. (1914: 354). Beccari

(1924: 10). Type: Papua New Guinea, Sepik River,

Heine s.n. (holotype FE!).

Stem

to

25

m tall, stem diameter unknown. Leaves 20 -

28 in the crown; petiole and sheath 150 - 300 cm

long; petiole 3.1 - 5.2 cm wide at midpoint, green

with very sharp black margins, but no spines (Fig. LA);

costa 130- 150 cm long; adaxial hastula conspicuous,

to 1.2 cm, abaxial hastula absent; lamina raditus

to

180

cm maximum; leaflets 50 - 90, 3.9 - 7.1 cm wide,

apices bifid and cuspidate, shortest leaflet 110 - 130

cm long, leaf divided to

76 - 92 cm; commissural veins

3 - 6 per cm, leaf anatomy dorsiventral. Staminate

inflarescences

branched to one order, upper subtending

branches terminating in 1 rachilla; rachillae brown

and catkin-like, ? 70 cm long, 2.7 - 4.3 cm diameter;

rachilla bracts forming pits containing a cincinnus of

6 - 12 flowers. Pistillate inJlorescences

spicate; flower

bearing portion 37 - 49 cm long with 7 - 22 flowers

arranged spirally. Staminateflowers

exserted from pits

individually,

0.4 - 1 cm long, bracteoles 1

x 1

cm; calvx

0.3 x 0.8 cm, shallowly to deeply divided into three

sepals, petal lobes 0.2 x 0.1 cm; stamens 6 with very

short filaments, 0.11 x 0.15 cm, anthers 0.18 x 0.06

cm; pistillode distinct, 0.2 - 0.5 x 0.02 cm. Pollen

monosulcate, elliptical, 51 - 70 pm long, aperture 41 -

63 'im long, polar axis 37 - 57 pm long; tectum

perforate, sparsely covered with supratectal gemmae

(Fig. 2G). Pistillateflowers

2.5 x 2 cm; bracteoles large,

1.5 cm diam., sepals 1.5 x 2 cm, petals 1.0 x 1.5 cm.

Fruits large, 12 - 15 x 8

- 10 cm, ovoid with a slightly

pointed apex, greenish black; pyrenes 1

- 3, 9.2 - 10.5

cm x 4.8 - 7.0 cm x 4.0 - 4.5 cm; endocarp sometimes

with flanges that penetrate the seed. Figs 3

& 4.

DISTRIBUTION.

Endemic to New Guinea. Occurring in

both Papua New Guinea and Indonesian Papua, but

restricted to the

northern side of the island.

SPECIMENS EXAMINED. INDONESIA. Papua Prov.:

Jayapura Regency, Bernhard Camp, Idenburg River,

April 1939, Brass 13775 (A, BRI, L); same date and

locality,

Brass 13945 (A, L) [Brass specimens verified

by

W. J. Baker]; Sarmi, 1

- 3 km N of Sewan on

Waske

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Trustees of the

Royal Botanic Gardens, Kew, 2007

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570 KEW BULLETIN

VOL. 62(4)

3 cm 3 cm 3 cm

30 cm 3 I

'?

5 mm

cm ~ 1m

1 cm~~~~~~~~~~~~~5c

Fig. 3. Borassus heineanus. A costapalmate leaf; B junction of lamina and petiole

with adaxial hastula; C leaflet apex with detail

of

commissures;

D section of unarmed petiole; E partial staminate inflorescence with detail of rachilla surface; F staminate rachilla in transverse

section; G staminate rachilla in

lon-gitudinal

section; B staminate cincinnus; J staminate flower; K staminate flower in

longitudinal

section

(note elongated pistillode). A & E from photographs; B - C,

Kjaer

525 (AAU); D & F - K,

Banka

s.n. (K). DRAWN

8Y LUCY

T. SMITH.

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Kew,

2007

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A REVISION OF BORASSUS L.

(ARECACEAE) 571

E /~~~~4c

3

cm

cm V 4 cm

3 cm ~ ~ ~ ~ ~ ~ * c

N~~~~~~~~~

Fig. 4. Borassus

heineanus. A pistillate

infructescence;

B pistillate

flower;

C immature

fruit;

D

mature fruit;

E pyrene;

F

pyrene

in

longitudinal

section;

G pyrene

in

transverse

section

(no internal

walls); H pyrene in

transverse

section

(with

internal

walls).

A - C & G

K]ser

525 (AAU);

D -F & H

Ferrero

&

Barfod

420 (AAU).

DRAWN BY

LUCY T.

SMITH.

?)

The

Board

of

Trustees of

the

Royai

Botanic

Gardens,

Kew,

2007

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572 KEW BULLETIN

VOL. 62(4)

River, 1

June 1993 (9), McDonald

& Ismail

3763

(CANB!, K!). PAPUA NEW

GUINEA.

East Sepik Prov.:

Angorain sub-district, ca. 5 miles N of Timbunke on

track to

Kwoiwut, 12 Sept. 1959 (9), Pullen 1719

(CANB!); 15 km

N of Sepik River, between Timbunke

& Angoram, 19 April 2000 (9), Kjalr 525 (AAU!);

Morobe Prov.: cultivated, Papua New Guinea Forest

Research Institute, Lae, Oct. 2001 (cd), Banka s.n.

(K!, LAE); West Sepik Prov.: Beisom Non by

Bitro

Creek, ca. 12 km from Bitro village, 30 Nov. 1996 (9),

Ferrero 420 (AAU!); Green River, ca. 5 km downstream

from Beimap, 30 Nov. 1996 (seedling), Ferrero

422

(AAU!); Green River District, Bitro village, 30 Nov.

1996 (9 & Cr), Ferrero

423, 424 (AAU!)

HABITAT.

Tropical rain forest on alluvial sands (Barfod

et al. 2001). The palm may also be cultivated (Kjzer

2003).

CONSERVATION STATUS. Data deficient. Borassus

heineanus has been collected in only seven locations

in New Guinea. Kjaer (2003) reported a stand of

approximately 300 x 300 metres in an area by the

Sepik River in Papua New Guinea. Additional

localities may exist, and further collections are

needed.

ETYMOLOGY.

After Georg Heine, administrator with

the German New Guinea Company, who collected

the type specimen.

VERNACULAR NAMES. Beiwof (Apau), Lipmemon

(Kamangauwi dialect).

USES. Very little is known about the uses of B.

heineanus, though Kjoer (2003) reports that the leaves

are used for thatch.

NOTES. Borassus heineanus is by far the most distinctive

species in the genus and this led Beccari (1924) to

speculate that it should be transferred into

Borassodendron. Both B. heineanus and Borassodendron

occur in humid rain forest, gene'rally an atypical

habitat for

Borassus. Unlike all other Borassus species,

the petiole is always unarmed, the leaves have a

dorsiventral leaf

anatomy and cuspidate leaflet apices,

the staminate inflorescence branches to one order

only and the staminate flowers have a large pistillode.

However, the pollen is

very similar to that found in

the other Borassus species; it has a sulcate aperture

that is

almost the length of the grain and a perforate

tectum with sparse supratectal gemmae (Fig. 2G). In

contrast, the pollen of Borassodendron has a porate

aperture and no gemmae (Ferguson et al. 1986).

Preliminary results from the molecular study confirm

the monophyly of Borassus in its current

circumscription (including B. heineanus) and suggest

that

Borassodendron is sister to Borassus (Bayton 2005).

The pyrenes of Borassus heineanus are rather

unusual for the genus. In most Borassus species,

pyrene length and breadth are similar or equal, but

in B. heineanus, the pyrenes are much longer than

wide (Fig. 4E). In some specimens, the endocarp has

a number of internal flanges that

penetrate the seed

(Fig. 4H). The flanges are perpendicullar to the

main

endocarp wall and are only visible

when the

pyrene is

viewed in transverse section. A sectioned pyrene in

the type specimen does not have internal flanges.

This character distinguishes Borassodendron (with

internal flanges) from all other Borassus species and

could indicate that a second unidentified Borassus

species occurs in New Guinea. However, no

additional morphological characters could be found

to distinguish between specimens with or without

internal flanges. The adaptive significance of these

flanges is uncertain. While living material of B.

heineanus has never been collected outside New

Guinea, two endocarps (Degener

& Degener 24625,

BH) found on a beach on the Pacific island of

Canton (Phoenix Is., Kiribati) were identified as

belonging to Borassus (Degener & Degener 1974)

and are probably attributable to this species. The

endocarps are rather long and narrow and have

perpendicular internal flanges (see Gunn & Dennis

1976: 177). These characters set them apart from all

other Borassus species. However, typical

endocarps of

B. heineanus have a small hole in the

apex to

allow the

cotyledonary stalk to exit. The Canton endocarps

have deep V-shaped clefts at the apex, usually filled

with black fibres (fibres eroded in one pyrene).

There is a great deal of natural variation in the

endocarps of better-known Borassus species. Perhaps

when more material is

collected in

New Guinea, the

presence of internal flanges or apical V-shaped clefts

in the endocarp will fit into the natural range of

variation exhibited by

B. heineanus.

2. Borassus flabellifer L. (1753: 1187). Bailey (1902:

1686); Cooke (1907: 811); Blatter (1912: 930);

Beccari (1914: 304; 1924: 4); Gamble (1922: 737);

Gagnepain & Conrard (1937: 998); Malik (1984: 5);

Pei (1991: 46); Hodel (1998: 20); Zoysa (2000: 49).

Type: Ampana Rheede (1678: 13-14, pl. 10) and

Carimpana Rheede, (1678: 11-12, pl. 9), (Lectotype

chosen by Moore & Dransfield, 1979: 60 [Ampana

designated lectotype if only one element is

selected]).

Borassuis flabelliformis

L. (1774: 827) [orthographic

variant], see note below. Roxburgh (1795 - 1798:

50); Martius (1838: 219); Kunth (1841: 222);

Miquel (1855: 45); Kurz (1877: 529). Type: as B.

Jlabellifer

L.

Lontarus domestica Gaertn. (1788: 21). Type: as B.

flabellifer L., see note below.

Borassus tunicatus Lour. (1790: 619). Kunth (1841:

224). Pholidocarpus tunicatus (Lour.) H. WAendl. ex

B. D. Jacks. (1894: 502), see note below. Type:

'Habitat in India ad oras regnorum Decan, and

Guzerate', see note below.

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A REVISION OF BORASSUS L. (ARECACEAE) 573

Borassus sundaicus Becc. (1914: 321). Beccari (1924:

321); Backer & Bakhuizen van den Brink (1968:

176). Type: Indonesia, cultivated, Bogor Botanic

Gardens, no date or collector (holotype Fl!).

Stem to 20 m tall, grey with

well-defined leaf scars,

not

ventricose, but often enlarged at the base, branching

occasionally when damaged. Leaves petiole and

sheath 150 - 180 cm long; petiole 4- 6(- 7) cm wide

at midpoint, robust, bright yellow, margins black with

short (0.3 -1.3 cm) black erose teeth (Fig. 1B); costa

60 - 110 cm long; adaxial hastula conspicuous,

abaxial hastula rudimentary; lamina radius to 150 cm

maximum, dense adaxial and abaxial- indumentum

on the ribs of some juvenile leaves, leaflets -62, 4.2 -

9.5 cm wide, apices acute and entire or splitting

longitudinally with age, shortest leaflet 13 - 39 cm

long, leaf divided to 30 - 100 cm; commissural veins

11 - 18 per cm, leaf anatomy isolateral. Staminate

inflorescences branched to two orders, upper

subtending branches terminating in 1

- 3(- 4)

rachillae; rachillae green to

brown and catkin-like, 23

- 50 cm long and 1.8 - 2.5 cm diameter, sometimes

with a mamilliform apex, rachilla bracts forming pits

containing a cincinnus of 4 - 7 flowers. Pistillate

inflorescences

usually spicate (branched inflorescence

pictured in the lectotype), flower-bearing portion 12

- 85 cm long with 5 - 20 flowers arranged spirally.

Staminate flowers

exserted from

pits individually,

0.24 -

0.6 cm long, bracteoles 0.4 - 0.7 x 0.1 - 0.3 cm, calyx

0.3 x 0.15 cm and shallowly divided into three sepals,

petal lobes 0.1 x 0.1 cm; stamens 6

with very short

filaments, 0.2 x 0.03 cm, anthers, 0.05 x 0.03 cm;

pistillode minute. Pollen monosulcate, elliptical, 48 -

95 pm long, aperture 40 - 95 pm long, polar axis 30 -

89 pm long; tectum perforate, sparsely covered with

supratectal gemmae (Figs 2C & 2E) .

Pistillate

Jlowers

3

x 3 cm; bracteoles large, 2 cm diam., sepals 1.5 x 2

cm, petals 1 x 1.5 cm. Fruits

massive, 8.5 - 13 x 7.5 -

16.5 cm, yellowish black, ovoid and rounded or

flattened at the apex; produced inside persistent

perianth segments; epicarp coriaceous, mesocarp

pulp yellow, pyrenes 1

- 3, 6.1 - 10.8 cm x 4.4 - 8.5

cm x 3.1 - 4.6 cm, somewhat bilobed; most pyrenes

with one or two external, longitudinal fturrows;

internal flanges absent.

DISTRIBUTION.

South and Southeast Asia. Determining

the 'natural' distribution of Borassus flabellifer is

essentially impossible as it is a widely planted crop

plant. It is largely restricted to areas with seasonal

rainfall and ranges from western India through

Indochina to the Lesser Sunda Islands of Indonesia.

Populations in

China, Malaysia and Pakistan may be

introduced (Whitmore 1973; Malik 1984; Pei 1991).

Borassus flabellifer

was noted to

occur in

Queensland,

Australia by Bailey (1902). A seedling

was

collected

from a small poptulation of mature palms and

cultivated in the garden of Frank L. Jardine in

Somerset on the Cape York Peninsula of northern

Queensland. Jones (1984) noted that the palm was

still present in the garden of Jardine's abandoned

house, but the original population was never located

and the natural occurrence of Borassus in Australia is

doubtful. The Borassus palms on the island of Soqotra

have tentatively

been assigned to B. flabellifer.

Soqotra

is

geographically closer to Africa and the

palms were

identified as the

African B. aethiopum by Miller &

Morris (2004). The available herbarium material

does not allow for a conclusive identification (the

diagnostic fruits

and petiole spines are missing), but

a photograph presented by Miller & Morris (2004)

shows a mature plant without a ventricose stem. This

suggests that the

palms, which were introduced to the

island, are B. flabellifer.

SPECIMENS EXAMINED. BANGLADESH.

Chittagong, 1867

( a), JSI-IfJ s.n. (K!); Chittagong Hill Tracts,

March

1880, Gamble 7781 (K!); Dhaka, 25 March 1868, Clarke

6673 (Fl!). INDIA.

Orissa State: Anugul, 19 March 1903

(a'), Haines 4034 (K!); Tamil Nadu State:

Tiruchchirappalli, 4 April 1974 (9), Mathew 7145

(K!); Madras [Chennai], Kristna Distr., 1 Jan. 1883

(da), Gamble 18581 (K!); Uttar Pradesh State: Banda,

9

May 1901 (d), Bell 320 (K!); West Bengal State:

cultivated, Calcutta [Kolkata] Botanic Gardens, 1869

(9 & c'), Wallich 8622 (K!,

K-W!); same locality,

1906

(9 & a'), Gage s.n. (FI!); Calcutta [Kolkata], 1881

(9), King 69 (K!). INDONESIA.

East Nusa Tenggara

Prov.: West Timor, Kupang, 1973 (9 & d), Fox s.n.

(BH!); South East Sulawesi Prov.: Pulau Buton, 2004

(9), Rustiami 222 (BO, K!). MALAYSIA.

Kelantan State:

Tumpat, 5 May 1937 (9), Corner 32784 (BH!, K!).

SINGAPORE. Cultivated, Singapore Botanic Garden (9),

Furtado s.n. (BH!); same locality (ad), Futrtado

32447

(BH!, K!). SRI

LANKA.

Central Prov.: cultivated, Royal

Botanic Gardens, Peradeniya, 22 July 1986 (9 & d),

Rutherford 115 (K!); North Central Prov.: 5 km from

Anuradhapura, 19 Sept. 1989 (9 & da), Zoysa

49 (K!).

THAILAND. Unknown locality, 1859 (ad), Schomburgk

s.n. (BH!, K!); Bangkok Prov.: Bangkok, 30

May 1906

(ad), Kerr 10708 (AAU!, BM!, K!); Bangkok, 20 May

1926 (da), Marcan 2097, 2098 (BM!); 39 km S of

Bangkok, 31 July 1963 (9 & d), King 5565 (BH!);

Nonthaburi Prov.: no locality, 24 May 1997 a(d),

Niyomdham 5038 (AAU!, K!); Phichit Prov.: 81.5 km

from Nakhon Sawan on Route 117, 26 April 2002

(a), Wilkin et al. 1160 (K!); Rayong Prov.: Salut,

Klaeng, 14 March 1928 (9), Kerr 14581 (BM!);

Songkhla Prov.: Road from

Songkhla - Sathing Phra,

11

Nov. 1990 (9Q

& da), Barfod 41256 (AAU!); Ban si

Chai Noi, 7 March 1994 (9 & d), Barfod 45286,

45287 (AAU!). YEMEN. Soqotra, unknown locality,

1880 (da), Balfour s.n. (K!); Hadiboh Plains, 1967.

(9), Smith s.n.

(K!)~

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574 KEW

BULLETIN VOL. 62(4)

HABITAT. It is difficult to determinie the original

habitat of B. flabellifer

as its distribution is so heavily

influenced by man. It occurs between sea level and

800 metres, though is

more abundant at low altitude

and is particularly common in coastal areas with

sandy or alluvial soils and in areas with permanent

soil

moisture such as flood plains and river

valleys. It

is

commonly grown along the

margins of rice paddies

forming one of the

most distinctive landscapes of

Southeast Asia.

CONSERVATION STATUS.

Least concern. Borassusflabelfer

is

widely distributed and is

common in cultivation.

The abundance of products extracted from it

will

effectively

ensure its continued survival.

ETYMOLOGY. The epithet 'flabellifer' translates as

'producing fans' and refers to the

palmate leaves.

VERNACULAR

NAMES. Kerigi (Soqotra), Miak tan kok

(Lao), Panna-maram (Tamil, Sri Lanka), Taan, T/han

or Tan (Thai). There are many other names applied

to this

widespread species (see Kovoor 1983), but the

name palmyrah (or palmyra), derived from the

Portuguese palmeira, has become the internationally

familiar vernacular name.

USES.

Almost every part of the palmyrah palm can be

used. The wood is thought to be termite resistant

and

is

used for construction (houses, canoes, fence posts

etc.). The leaves are used for thatch,

weaving and for

making containers for some foodstuffs. The leaflets

of B. flabellifer (together with those of Corypha

umbraculifera L.) are traditionally used as a writing

surface. They are marked using a hot metal stylus

with the parallel veins providing a convenient line

upon which to

write (Sankaralingham & Hameed

Khan 2001). Palmyrah provides a variety

of foods; the

fruits,

undeveloped endosperm and apical bud (palm

cabbage) are consumed and the inflorescences are

tapped for the sweet sap. This can be fermented into

palm wine or the sugar can be crystallised. On some

Indonesian islands, this sugar is the primary source of

carbohydrates (Fox 1977). For a review

of the

uses of

B. flabellifer,

see Kovoor (1983) and Mortoil (1988).

NOTES. A number of nomenclatural problems were

uncovered while investigating the synonymy of B.

flabellifer.

The account of Borassus flabelliformis

L. in

Systema Vegetabilium (Linnaeus 1774) matches

exactly that of B. flabellifer in Species Plantarumr

(Linnaeus 1753), and the epithets are similar,

suggesting that the former is an orthographic

variant of the latter. It could be argued that the

change in epithet was intentional, but this

wvould

render B. flabelliformis illegitimate, as both names

are based on the same type

material (Challis, pers.

comm.). When describing Lontarus domestica,

Gaertner (1788) cited the same material as

Linnaeus (1753) plus an un-named Banks

specimen, which could not be located after a

thorough search of the

Banks collection at BMN

(Vickery pers. comm.). Pholidocarpus tunicatus is

attributed to Wendland (1878: 235) in a number of

publications including Govaerts and Dransfield

(2005). However, Wendland did not make the

combination, but rather, states under Borassus

tunicata Lour., "vide Pholidocarpus" (Merrill 1935:

92). The name does not appear in the account of

Pholidocarpus, nor in the index; the combination is

therefore attributed to Jackson in Index Kewensis

(1894: 502). No original material could be found in

the Loureiro collection at BM to typify Borassus

tunicata (Vickery pers. comm.).

Borassus sundaicus was placed in synonymy with B.

flabellifer by Govaerts and Dransfield (2005), though

not noted as a new synonym. The diagnostic

characters cited by Beccari (shape of perianth

segments, endocarp crest size, seed shape) are largely

continuous when examined across the

Asian material.

The only qualitative characters cited are leaf scales

(present in B. flabellifer

and absent from B. sundaicus),

and the arrangement of perianth segments in the

fruit (imbricate in B. sundaicus, but not in B.

flabellifer). In most Borassus species, leaf scales and

indumentum are present on immature leaves, but

they erode as the leaves

mature. In addition, a degree

of overlap can be observed in the perianth segments

of

most Borassus species. Therefore these characters

are not taxonomically informative. Pollen from an

Indonesian specimen of B. Jfabellifer

(Fox s.n.) was

significantly larger than that from either the Thai or

Sri Lankan specimens. A sample of ten pollen grains

was measured from each specimen; the Indonesian

pollen was 70 - 95 pm long (mean 84.8 pm) while

pollen from Sri Lanka was 45 - 65 pm long (mean

53.6 pm) and pollen from Thailand was 51 - 72 pm

long (mean 60 pm). There were no noticeable

structural differences between the pollen samples.

Given the rather limited sampling of Indonesian

Borassus, it is difficult to determine whether this

aberration is

distinctive or

whether it fits within the

range of variation exhibited by B. flabellifer

across

Asia. However, after examination of images of the

type specimen of B. sundaicus, I can find no

additional morphological characters to distinguish

this taxon from B. flabellifer.

3. Borassus akeassii Bayton, Ouedraogo & Guinko

(2006: 354). Ake Assi & Guinko (1996: 777) [as

Borassus sp. (B. flabellifer?) ];

Arbonnier (2002: 174)

[as Borassus sp. aff.

flabellifer];

Ake Assi et

al. (2006:

54). Type: Burkina Faso, Comoe Province, 1

km S of

Banfora, 20 Jan. 2004 (9), Bayton et

al. 69 (holotype

K!, isotypes

FTG!, OUA!).

?Borassus aethioppurn

var. domesticus

A. Chev. (1938: 103).

Type: Mali, Kaves Region: l'ile de Dinguira, Dubois

s.n.

(holotype

P') nom. inval., sine diagn. lat.

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A REVISION OF BORASSUS L. (ARECACEAE) 575

Stem to 15 m tall, almost always ventricose, to

80 cm

diam., when stem marked by numerous irregular

scars, this is caused by tapping (Fig. 5A). Leaves

glaucous, 8 - 22 in the crown; petiole and sheath 90 -

160 cm long; petiole 3.0 - 7.4 cm wide at midpoint,

green, margins with small serrate black teeth (0.2 -

0.6 cm long), or teeth largely

absent (Figs 1G - H, 5B

-

C); costa 22 - 28 cm long; adaxial hastula

conspicuous, to

2.4 cm, abaxial hastula rudimentary;

lamina rather flat, radius to 160 cm

maximum, dense

indumentum on the ribs of some immature leaves;

leaflets 45 - 82, 2.8 - 7.3 cm wide, apices acute and

entire or splitting longitudinally with age, shortest

leaflet 58 - 147 cm long, leaf divided to 60 - 99 cm;

commissural veins 5 - 7 per cm, leaf anatomy

isolateral. Staminate inflorescences

branched to two

orders, upper subtending branches terminating in 1

- 3 rachillae; rachillae green-brown and catkin-like,

23 - 36 cm long, 2.3 - 2.5 cm diameter, usually with a

mamilliform apex; rachilla bracts forming pits that

contain a cincinnus of 5 - 10 staminate flowers.

Pistillate inflorescences

spicate or branched to one

order; rachis ? 80 cm long, flower-bearing portion 24

- 39 cm long with ? 23 flowers arranged spirally.

Staminate

flowers

0.4 - 0.6 cm long, exserted from the

pits individually

or in groups of 3 - 5; bracteoles 0.8 x

0.5 cm; calyx 0.5 x 0.2 cm, shallowly divided into

three sepals, petal lobes 0.2 x 0.1 cm; stamens 6

with

very short filaments, 0.1 x

0.03 cm, anthers, 0.1 x 0.05

cm; pistillode minute. Pollen

monosulcate, elliptical,

51 - 72 pm long, aperture 47 - 61 pm long, polar axis

49 - 61 pm long; tectum reticulate, densely covered

with supratectal gemmae (Fig. 2D, 2F). Pistillate

flowers

3.5 x 3 cm, bracteoles 2 cm diam., sepals 2 x 2

cm, petals 1.5 x 1.5 cm. Fruits large, ? 15 cm long anci

+ 12 cm diameter, ovoid with a somewhat pointed

apex, fragrant and yellowish green at maturity,

produced inside persistent perianth segments;

pyrenes 1

- 3, 6.8 - 9.3 cm x 5.4 - 7.5 cm. Fig. 5.

DISTRIBUTION. Restricted to West and Central Africa.

Ake Assi and Guinko (1996) report that the

palm is

present in

Benin, Burkina Faso, C6te d'Ivoire, Mali,

Niger and Nigeria. Borassus akeassii (as Borassus sp.

aff.

flabellifer)

has also been recorded in

Senegal and

the Central African Republic (Arbonnier 2002).

However, the range of B. akeassii

may be much wider

than suggested due to

misidentification of the palm

as B. aethiopum.

Johnson (1984) noted that Borassus

aethiopum in Guinea-Bissau was used for wine

production. He also noted that the palms have green,

orange-sized fruits and both these facts suggest B.

akeassii. This study can confirm the presence of B.

akeassii in Burkina Faso and Senegal only. In addition,

a specimen collected in southeastern Congo-Kinshasa

(Liben 2822) has been identified as B. akeassii. The

identification

was based on the distinctive

commissUral veins (Bavton et

al. 2006); however, the

specimen included no fertile

material.

SPECIMENS EXAMINED. BURKINA FASO.

Comoe Prov.:

Banfora Dept., 1 km

W of Siniana village, 20 Jan.

2004 (d), Bayton et

al., 68 (AAU!, K!, OUA!); 500 m

N of Lake Tengrela, 22Jan. 2004, Bayton et

al., 72 (K!,

OUA!); 3 km N of Banfora, 22Jan. 2004 (9 & C),

Bayton et al., 73, 74 (AAU!, K!, OUA!); Wolonkoto

village, 29 July 1998, Ouedraogo & Boussim 9 (OUA!);

Houet Prov.: Bobo-Dioulasso Dept., Dinderesso

village, 28 July 1998, Ouedraogo

& Boussim 8 (OUA!);

Kadiogo Prov.: Somgande, 18June 1998, Ouedraogo &

Guinko 2, 3 (OUA!); Ouagadougou city

centre, 4July

1998, Ouedraogo 4 (OUA!); Ouagadougou Forest, 5

July 1998, Oud,raogo 5 (OUA!). CONGO-KINSHASA.

Kasai-Occidental Prov.: Kamulolo, without date, Liben

2822 (K!). SENEGAL.

Senegambie, 1840, Brunner s.n.

(K!); Kaolack Region: Kaolack, 1906, Chevaliers.n. (P!);

Louga Region: Lingtuere Dept., Velingara in Ferlo, 30

Oct. 1989 (d), Lawesson 5444 (AAU!); Thies Region:

Mbour Dept., Ndianda village near Joal, 7 Dec. 1997

(9 & d), Ervik & Sccmbou 307 - 309 (AAU!).

HABITAT.

Sudan savannas with 800 - 1100 mm annual

rainfall. In Burkina Faso, most populations are semi

managed for wine production. Seed is collected and

planted and the palms often have crops planted

beneath (usually cotton or cassava).

CONSERVATION STATUS.

Data deficient. Borassus akeassii

may have a much wider distribution than is

currently

known. However, in the areas where it is known to

occur, it is abundant and a significant crop for local

people. Sambou et

al. (2002; 1992) report that

over

exploitation is threatening populations of B.

aethiopurn in

Guinea and Senegal, but it is

possible

that these refer to B. akeassii. In many cases, it is

difficult to determine whether populations of B.

akeassii are cultivated (i.e. planted) or merely wild

plants that

are exploited.

ETYMOLOGY. Borassus akeassii honours Professor

Laurent Ake Assi (Abidjan University, C6te d'lvoire)

who, together

wvith

Professor Sita Guinko (University

of Ouagadougou, Burkina Faso) first

distinguished

the palm from B. aethiopum (Ake Assi & Guinko

1996).

VERNACULAR NAMES. Burkill (1997) lists a huge

number of indigenous names for

Borassus (ostensibly

B. aethiopum) in West Africa and many of these

may

be applicable to B. akeassii.

The French name r6nier

(derived from the

Wolof word r6n) is

widely used in

Francophone Africa for

both Borassus species.

USES. In Burkina Faso, the main use for the palms is

wine production, whereby the terminal bud is tapped

to

produce a stugary

solution that

is

allowed to ferment.

The undeveloped endosperm is

also consumed, and

the leaves are used for thatch

and weaving.

NOTES. Initial examination of B. akeassii suggests a

close relationship with B.

flazbellifer,

as suggested by

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Kew,

2007

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576 KEW BULLETIN VOL. 62(4)

5

cmScA SmG

'~

Fig. 5. Borassus akeassii.

A habit,

with stem damaged by man; B petiole section without spines;

C petiole section with spines

(immature); D section of leaflet

with detail of commissures; E partial staminate inflorescence;

F partial staminate rachilla with detail

of

multiple flowers emerging from pits;

G partial pistillate inflorescence (flowers detached); H infructescence branched to one order. A & H

from photographs; B & D - E from Bayton et a!.

74 (K); C from Bayton et a!.

72 (K); F from

Bayton et a!.

73 (K); G from Bayton et a!. 69

(K). DRAWN

BY

LUCY T. SMITH.

? The Board of

Trustees

of the Royal

Botanic Gardens, Kew, 2007

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A REVISION

OF BORASSUS

L. (ARECACEAE) 577

previotus authors (Ake Assi & GuLinko 1996;

Ouedraogo et

al. 2002). The similarities are largely a

matteir of scale, as B. akeassii is considerably smaller

than other African Borassus species. This has been

attributed to the intensive extraction of sap leading

to reduced growth (Porteres 1964). The small leaves,

petiole spines, inflorescences and fruits are

reminiscent of those of B. flabellifer.

However, B.

akeassii has a ventricose stem and that character is

restricted to African Borassus.

The rate of occurrence of branched pistillate

inflorescences is much higher in B. akeassii than in

any other species. Branching may occur in the

rachis towards the base of the inflorescence, or in

the flower-bearing rachillae. This may also be an

artefact of husbandry as wine tapping damages the

apical bud.

Further investigation has revealed a number of

characters that are unique to this species and

probably independent of husbandry. The pollen is

particularly distinctive (Fig. 2D, 2F); the gemmae

are denser and almost completely obscure the

tectum whereas it is clearly visible in the pollen of

all other Borassus species. In the few areas where the

tectum can be seen, it is reticulate rather than

perforate. The commissural veins in the leaves are

spaced further apart than in any species except B.

heineanus. This character can be used to identify

sterile herbarium material of B. akeassii. As the leaf

desiccates, the lamina collapses onto the network of

veins; in the leaves of B. flabellifer

and B. aethiopum

the commissures are close together and suipport the

lamina, resulting in a smooth surface. In B. akeassii,

the commissures are widely-spaced so the lamina

sinks into the rectangular pits formed bv the veins

resulting in a puckered appearance (Bayton et al.

2006). The fruits are yellow-green with a pointed

apex, thus resembling those of B. madagascariensis,

but they

are considerably smaller. These characters

should ensure that living specimens can be

identified to

species, whether they have been tapped

or not.

It is conceivable that B. aethiopum var. domesticus

could represent B. akeassii,

as the fruits

are described

by

Chevalier as small, globose, and yellowish-green in

colour. His choice of epithet reflects the importance

of this

variety to local people (Chevalier & Dubois

1938), which is

mirrored by B. akeassii. However, the

type

of var. domesticus consists of pyrenes only, and

these cannot be identified with certainty. The

presence of a second species in

West Africa could

cause some nomenclatural difficulties as the type

of

B. aethiopum is lost and was originally collected in

W\Vest

Africa. However, modern material collected

from the type locality of B. aethiopum can be

identified as that species.

4. Borassus aethiopum Mart. (1838: 221). Kunth

(1841: 223); Beccari (1914: 325; 1924: 6); Hutchinson

& Dalziel (1936: 392); Dransfield (1986a: 19); Bekele

Tesemma et al. (1993: 112); Tuley (1995: 20); Ake

Assi & Guinko (1996: 773); Arbonnier (2002: 173

[excluding top photograph]); Coates-Palgrave (2002:

99); -Bayton et al. (2003: 216); Ake Assi et al. (2006:

53). Type: Ghana, Thonning 258 (holotype lost, see

Hepper, 1976: 154); Ghana, Weija, 24

April 1957 (Q

& Cf), Tomlinson s.n. (neotype, chosen here, BH!).

Borassusflabellifervar. aethiopum (Mart.)

Warb. (1895:

20). Drude (1896: 120); Wright (1902: 117). Type:

as B. aethiopum

Mart.

Borassus sambiranensisJum. & H. Perrier (1913: 67).

Beccari (1914: 346; 1924: 8); Jumelle (1938: 7);

Jumelle & Perrier de la Bathie (1945: 13);

Dransfield & Beentje (1995a: 54); Bayton et al.

(2003: 214). synon. nov. Type: none cited;

Madagascar, Antsiranana Prov., Ambanja, 28

March 2003 (ad), Bayton & Ranaivojaona 55

(neotype, chosen here, K!, P', TAN!).

Borassus deleb

Becc. (1914: 339). Beccari (1924: 8).

Type: Sudan, unknown locality and date (9),

Salvago Raggi s.n. (holotype FI').

Stem to 25m tall, almost always ventricose, to 80cm

diameter. Leaves 18 - 27 in the crown; petiole and

sheath 130 - 220 cm long; petiole 3.2 - 9 cm wide,

robust,

with large (0.4 - 2.8 cm long), recurved black

teeth

on the

margins (Fig. 1D - 1F), yellow-orange in

the distal portion, darkening to

brown-black towards

the trunk, though in immature plants, the

petiole may

be completely black; petiole spines extending along

the

margin of the first

leaflet;

costa 80- 170 cm long;

adaxial hastula conspicuous, to 2.9 cm high, abaxial

hastula rudimentary; lamina radius to 190 cm

maximum, dense indumentum on the ribs of some

immature leaves; leaflets 86 - 120, 4.7 - 11 cm

wide,

apices acute and entire or splitting longitudinally

with

age, shortest leaflet

45 - 92 cm long, leaf

divided to 58

- 95 cm; commissural veins 8 - 15 per cm, leaf

anatomy isolateral. Staminate inflorescences

branched to

two

orders, upper subtending branches terminating in

1

- 3 rachillae; rachillae green-brown and catkin-like,

37- 50 cm long, 2.3 - 3.8 cm diameter, sometimes

with

a mamilliform apex; rachilla bracts form pits that

contain a cincinnus of 8 - 14 staminate flowers.

Pistillate inflorescences

spicate; flower-bearing

portion 36

- 160 cm long

with 10 - 28 floNvers

arranged spirally.

Staminate flowers 0.2 - 0.7 cm long, exserted

individually from the pits; bracteoles 0.8 x 0.5 cm;

calyx 0.4 x 0.2 cm and shallowly divided into three

sepals, petal lobes 0.15 x 0.1 cm; stamens 6 with very

short filaments,

0.02 x

0.04 cm, anthers 0.02 x 0.05 cm;

pistillode minute. Pollen

monosulcate, elliptical, 49 -

71 um long, aperture 37 - 71 ilm long, polar axis 32 -

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578 KEW BULLETIN VOL. 62(4)

61 pm long; tectum perforate, sparsely covered with

supratectal gemmae (Fig. 2A - 2B). Pistillate

flowers

3 x

3 cm, bracteoles 2 cm diam., sepals 1.5 x 2 cm and

petals 1 x 1.5 cm. Fruits

massive, 7- 17 x

7- 11 cm,

ovoid, flattened at the apex, or with a depressed apex;

fragrant, yellow to

orange or red at maturity; produced

inside persistent perianth segments; pyrenes 1 - 3, 6.4

- 10.9 cm x 5.4 - 8.0 cm x 4.2 - 5.7 cm, somewhat

bilobed; some pyrenes have one or two external

longitudinal furrows; internal flanges absent.

DISTRIBUTION.

Found across sub-Saharan Africa as far

south as northern South Africa. Absent from

parts of

southwest and central Africa, and the Horn of

Africa.

Present on a number of offshore islands including

Sao Tome and Bioko in the Gulf of Guinea, three of

the Cape Verde Islands, and Pemba, Zanzibar and

Mayotte in the

Mozambique Channel. Present in the

Sambirano region of northwest Madagascar,

including the islands of

Nosy Be and Nosy Mitsiou,

though it

may be introduced there (Bayton et al.

2003).

SPECIMENS EXAMINED. BURKINA FASO. Ganzourgou

Prov.: Zam Dept., Rapadama, 17 Nov. 1997 (C),

Barfod 525 (AAU!); Kompienga Prov.: Pama Dept.,

Kabonga village, 1

1 Jan. 2004 (9), Bayton &

Ouedraogo 58 (K!, OUA!); Waongo village, 12 Jan.

2004 (9 & d'), Bayton & Ouedraogo 59, 60 (K!,

OUA!); Tapoa Prov.: Arli National Park, 13 Jan. 2004

(dC), Bayton

& Ouedraogo 61 (K!,

OUA!); 14Jan. 2004

(9 & C'), Bayton & Ouedraogo 62, 63 (K!, OUA!).

CONGO-KINSHASA.

Kasai-Oriental Prov.: Gandajika, no

date, Liben 2817 (K!); Sud-Kivu Prov.: Impakivu

Bukavu, Kabambare, no date (d), Christiaensen 711

(K!). C6TE

D'IVOIRE.

Bas-Sassandra Region: Nero-Mer, 8

km NE of

Grand-Berebi, 12 Nov. 1963 (d), Oldeman

625 (K!); Lagunes Region: between Bingerville and

Potou Lagoon, 1907, Chevalier 20073 (P!); Savanna of

Cosrou, 1962 (9 & d), Leeuwenberg 4242, 4243 (K!):

Sud-Comoe Region: Assinie, Danui, 1907, Chevalier

16312 (P!). ETHIOPIA. Benishangul-Gumaz Region: W

of Gubla village, 13 Oct. 1996, Friis 7767 (K!);

Gambela Region: 5 km S of Abobo, 22

Nov. 1995 (9),

Friis 7270 (K!). GHANA. Ashanti Region: Ejura, 1921,

Chipp 773 (K!); Greater Accra Region: Accra, 1899,

Sanders s.n. (K!). KENYA.

Coast Prov.: Lamu Distr.,

Garsen (Tana River), 26 Dec. 1975 (9 & C'),

Dransfield 4810 - 4813 (EA!, K!); Kilifi Distr., Rabai,

10

Oct. 2002 (9 & C'), Bayton

& Obunyali 1, 2 (AAU!,

EA!, K!); Kwale Distr., Pongwe, 15 Oct. 2002 (9 &

C), Bayton & Obunyali 14 -16 (AAU!, EA!, K!);

Mivumoni, 21 Oct. 2002 (9 & d), Bayton

& Obunyali

32, 33 (EA!, K!, NY!). MADAGASCAR. Antsiranana Prov.:

4 km S of Ambanja, 24 Oct. 1988 (C'), Schatz 2415

(K!, TAN!); Ananalava, 5 km SW of

Maromandia, 4

July 1992 (9 & C), Beentje 4708, 4709 (K!, TAM!); 16

km N of Ambanja, 26 NIarch 2003, Bayton &

Ranaivojaona 53 (K!, TA.N'!); 4 km S of Ambanja, 28

March 2003 (a

C), Bayton

& Ranaivojaona 55 (K!, P!,

TAN!); Nosy Be, Hell-Ville, 29 March 2003 (9),

Bayton

& Ranaivolaona 57 (K!, TANN!).

MALI.

Unknown

locality, 1937, Dzubois 255 (P!). NIGER. Dosso Dept.:

Dallol Foga, 1936, Auhreville s.n. (P!). NIGERIA. Delta

State: Asaba, 1906 (9), Unwin s.n. (FI!); Niger State:

Nupe, 1859 (d'), Barter 35109 (K!); SENEGAL. Thies

Region: Sebikotane, 1935, de

WVailly

4484 (P!). SOUTH

AFRICA. Limpopo Prov.: Leydsdorp Distr., no date (9),

Wicht s.n. (BM!). SUDAN.

Junqali State: Central Nuer

District, 6 Oct. 1957 (d), Basinski 12 (K!); Upper

Nile State: Taufikia, April 1904 (d), Brown

& Brown

s.n. (K!). TANZANIA. Mara Region: Ndaka Plain, 20

April 1961, Greenway 12420 (K!); Pemba South

Region: Makongwe Island, 1929, Greenway 1414, 1417

(K!); Pemba Island, 19

Oct. 1931, Burtt Davy 22551

(K!); Tanga Region: Pangani, Mkwaja Ranch, 12 Sept.

1955 (d), Tanner 2187 (BH!, K!); Mweni, 3 km S of

Tanga, 5 Jan. 1976, Dransfield 4818 (K!). ZAMBIA.

Southern Prov.: Mazabuka, Nampa Estates, 7 July

1963, Rensburg 1624 (K!). ZIMBABWE.

Masvingo Prov.:

Ndanga Distr., Nltilikwe River, 12 Dec. 1953 (d),

VVild 44830, 44909 (K!).

HABITAT.

Riverine forest and savanna in low-lying

areas, particularly on sandy or alluvial soils. Borassus

aethiopum

can form dense almost monospecific forest

stands or is a component of

more diverse riverine

forest.

However, it is

as the main component of palm

savannas for which it is best known. Borassus

aethiopum is well adapted to fire and herbivory and

prospers in areas with frequent burning and

browsing. After the pyrenes are dispersed, the

embryo is buried underground by the extending

cotyledonary petiole (Barot & Gignoux 1999). The

meristem is thus protected in the early years of life

during a period known as the establishment phase.

After several years surviving as a small cluster of

leaves, the palm finally generates a stem and this

grows rapidly. At this stage, the meristem is

vulnerable to fire and herbivory, but is

protected to

some extent by the skirt of dead leaves that clothes

the stem.

The dead leaf blades are highly-flammable,

but the

woody petioles are more persistent and this

may allow brush fires to

pass quickly; the leaf blade is

quickly consumed, but the petiole burns slowly,

keeping the fire

awvay

from the meristem. As a result,

the stem is covered with petioles, which may also

serve as a deterrent to large herbivores as the

petioles

are armed with spines. The accumulated leaf

sheathes and petioles are shed cleanly at maturity

(Barot & Gignoux 1999). At this

point, the

meristem

is

protected from fire and herbivory by

virtue of its

height above the

ground.

CONSERVATION STATUS. Least concern. Borassus

aethiopum is

widespread and common in a number of

African countries. While several populations are in

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A REVISION OF BORASSUS L. (ARECACEAE) 579

decline (Sambou et al. 1992; 2-002), the

palm remains

common. Borassus sambiranensis is listed by the IUCN

as endangered (EN Al c) due to habitat

loss/degradation and suppression of regeneration by

fire. It is perhaps unfortunate that by placing this

taxon in synonymy

with the widespread B. aethiopunm,

the conservation status of the Madagascar

populations will be masked.

ETYMOLOGY. 'Aethiopia' was a general term used by

the ancient Greeks and Romans for

Africa south of

Libya and Egypt.

VERNACULAR

NAME. Dimaka (Sakalava, Madagascar),

Kuhe (Ashanti, Ghana), Muhama (Kibuyu, Congo

Kinshasa), Mvumo (Kiswahili, Kenya & Tanzania). A

list

of West African vernacular names for B. aethiopum

is provided by Burkill (1997). European names

include African fan-palm, borassus-palm, rhun-palm,

ronier (French) and palma-do-vinha (Portuguese).

USES. In some parts of Africa, Borassus populations are

'managed' by local people, while in other areas the

palm is of minimal significance. In many areas,

Borassus aethiopum is restricted to game reserves and

national parks where it is outside the reach of local

people. The leaves are used for thatch and weaving,

though species of

Hyphaene are generally preferred.

The palm is tapped for wine, though the process is

different from that

used in Asia as the apical bud is

tapped rather than the inflorescences. The fruits,

undeveloped endosperm and cotyledonary stalks are

consumed. Burkill (1997) has reviewed the uses of

Borassus aethiopum in

West Africa.

NOTES. Historically, the key question in Borassus

taxonomy has been whether to recognise both the

African B. aethiopum and the Asian B. flabellifer.

Most

recent accounts do recognise B. aethiopum (Beccari

1924; Dransfield 1986a; 1988; Tuley 1995). The

molecular study of Kovoor & Hussein (1983) also

noted differences between the two species, thouLgh

the population sampling was extremely limited.

Qualitative characters that separate the two include

the stem (ventricose in B. aethiopum and not in B.

flabellifer),

petiole spines (large in B. aethiopum,

small

in

B. flabellifer),

and fruit

colour (black for

B. flabellifer

and yellow-orange for

B. aethiopum). Beccari (1924)

separated the African and Asian Borassus species

based on the

degree of division of the calyx lobes of

the staminate flowers. The calyx of

Asian species was

divided to the

base, while the calyx of

African species

was only divided to the middle. This character

appears to be nothing more than an artefact of

preparation. The calyx of most staminate flowers (of

either Asian or African species) is divided to the

middle. However, the transparent, membranous

partitions between the calyx lobes tear easily. The

resultant tear is perfectly straight, giving the

impression that the calyx is divided to the

base.

Dransfield (1986a) noted that B. aethiopum was

generally "more massive" than B. flabellifer

and for

several characters, this does appear to be the case.

The leaves have wvider

petioles with longer spines and

more leaflets, and the staminate and pistillate

rachillae are longer with more flowers. However,

while B. aethiopum and B. flabellifer

are at opposite

ends of the size range for some characters, other

Borassus species are intermediate and no truly

determinate quantitative characters were identified.

The Madagascar endemic B. sambiranensis

is placed

here in synonymy

with B. aethiopum as the two are

almost indistinguishable, both in the field and the

herbarium. Jumelle and Perrier de la

Bathie (1913)

describe in detail the differences between the two

Madagascar taxa and state that B. sambiranensis is

most similar to

B. aethiopum.

Beccari (1912 - 14, 1914,

1924) recognised B. sambiranensis, though only the

pyrenes

were available for him to

examine. He wrote

that they

resemble B. aethiopum var. bagamojensis

Becc.

and differ only in that there is a deep hollow at the

apex. The morphology of Borassus pyrenes is

extremely variable and this character alone is

insufficient to

warrant continued recognition of B.

sambiranensis.

No type specimen was cited byJumelle

and Perrier de la

Bathie, though it

could be Perrier

12069 (lower Sambirano valley) (Dransfield &

Beentje 1995a). However, this

specimen could not be

located and a modern neotype, collected in the

Sambirano valley,

has been designated.

Borassus deleb was placed in synonymy

with B.

aethiopum by

Dransfield (1986a), as the diagnostic

fruit characters of the former fit

within the range of

variation exhibited by the latter. Due to their large

size and fleshy

consistency, few whole Borassus fruits

are preserved in

European herbaria. New taxa were

erected on the basis of differences between these

fruits without taking into account the full range of

natural variation. In an attempt to counter this

problem, every fruit from three

Kenyan specimens of

B. aethiopum (159 fruits total) was measured in the

field.

The variation exhibited by those fruits already

encompassed almost all the variation in fruit size for

the whole genus. The fruit and leaf that are

illustrated as part of the type of B. deleb are not

significantly different from those of B. aethiopum.

Based on my own field observations and examination

of the type specimen, I agree with the conclusions of

Dransfield (1986a) to place B. deleb in synonymy

under B. aethiYtnsm.

A neotype has been designated for

B. aethiopum

as

the

holotype is

missing (Hepper 1976). The holotype

was collected in Ghana near Accra (Thonning &

Schumacher 1829). The neotype was also collected

near Accra and includes both staminate and pistillate

elements.

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580 KEW BULLETIN

VOL. 62(4)

5. Borassus madagascariensis (Jum. & H. Perrier)

Bojer exJu

m.

& H. Perrier (1913: 61). Beccari (1914:

349; 1924: 9);Jumelle (1938: 7);Jumelle & Perrier de

la Bathie (1945: 12); Dransfield & Beentje (1995a:

52); Bayton et al. (2003: 212). Type: none cited;

Madagascar, Mahajanga Prov.: Marovoay, 14

March

2003 (9), Bayton &Ranaivojaona44 (neotype, chosen

here, K!, P!, TAN!).

Barassus madagascariensis Bojer (1837: 308) nom. nud.

Borassus flabellifer

var. madagascariensis Jum. & H.

Perrier (1907: 389). Type: as B. madagascariensis

(Jum.

& H. Perrier) Bojer exJum. & H. Perrier.

Stem to 25 m tall,

almost always ventricose, to 80 cm

diameter. Leaves 16 - 23 in the crown; petiole and

sheath 170 - 237 cm long; petiole 7.8 - 9.2 cm

wide at

midpoint, robust, yellow-green along the whole length,

margins with small serrate black teeth, 0.1 - 0.85 cm

long (Fig. 1C); petiole spines extending along the

margin of the

first leaflet; costa 77 - 82 cm long; adaxial

hastula conspicuous, to 1.5 cm, abaxial hastula

rudimentary; lamina radius to 100 cm maximum,

dense indumentum on the ribs of some immature

leaves; leaflets

102 - 132, 4.2 - 7.9 cm wide, apices acute

and entire or splitting longitudinally

with age, shortest

leaflet 68 - 83 cm long; leaf divided to 61 - 83 cm;

commissural veins 10

- 14 per cm, leaf anatomy

isolateral. Staminate inflorescences

branched to two

orders, upper subtending branches terminating in 1

- 3

rachillae; rachillae green-brown and catkin-like, 30 - 44

cm long, 2.3 - 3.3 cm diameter, usually with a

mamilliform apex; rachilla bracts form

pits that

contain

a cincinnus of 8 - 12 staminate flowers. Pistillate

inflorescences

spicate; flower-bearing portion 76 - 90 cm

long with 7 - 15 flowers arranged spirally. Staminate

flowers

0.4- 0.7 cm long, exserted individually from the

pits, bracteoles 0.8 x 0.5 cm; calyx 0.5 x 0.2 cm,

shallowly

divided into three sepals, petals 0.2 x 0.1 cm;

stamens 6 with very short filaments, 0.02 x 0.04 cm,

anthers, 0.14 x 0.1 cm; pistillode minute. Pollen

monosulcate, elliptical,

46- 65 pm long, aperture 38 -

52 pm long, polar axis 42 - 54 pm long; tectum

perforate, sparsely covered with supratectal gemmae

(Fig. 2H). Pistillate flowers 3.5 x 3 cm, bracteoles 2 cm

diam., sepals 2 x 2 cm and petals 1.5 x 1.5 cm. Fruits

massive, 25 - 35 x

7- 18.5 cm, ovoid with a somewhat

pointed apex; fragrant

and yellowish green at

maturity;

produced inside persistent perianth segments; pyrenes

1

- 2(- 3), 8.7- 12.1 cm x 8.3 -12.3 cm x 6.3 - 7.5 cm,

unlobed or somewhat bilobed; some pyrenes

with one

or two

external longitudinal furrows; internal flanges

absent; an external, longitudinal crest is

common.

DISTRIBUTION. Endemic to

Madagascar, where it is

found in the dry western part of the island.

Populations in

Mahajanga Province are all in close

proximity

to

human

settlements.

There appears to

be

no overlap with the range of B. aethiopum in the

Sambirano region of northwest

Madagascar.

SPECIMENS EXAMINED. MADAGASCAR.

Mahajanga Prov.:

Lower valley of Tsiribihina River, 1933, Humbert s.n.

(P!); Berevo sur Ranoba, Sept. 1940, Decary 15892

(P!); Manombolo River gorges, 10 km E of Bekopaka,

26 March 1995 (9), Du Puy

& Du Puy 791 (K!, TAN!);

Antamanakana, 44 km SW of

Katsepy, 24July 1995 (9

& d), Noblick 5055 (FTG!, K!, TAN!); Marovoay,

Colonial Experimental Garden, Oct. 1908, Prudhomme

s.n. (FI!); environs of

Marovoav, 16 March 2003 (0'),

Bayton & Ranaivojaona 46, 47 (K!, P!, TAN!); Lake

Amboromalandy, 18 March 2003 (9), Bayton &

Ranaivojaona 48 (K!); Ankarafantsika National Park,

Ampijeroa Forestry Station, 19 NMarch

2003, Bayton

&

Ranaivojaona 49 (K!, TAN!); Ankijabe village, near

Ambato-Boeny, 19 March 2003 (0d), Bayton &

Ranaivojaona

50 (FTG!,

K!,

TANT!);

Maevatanana, 21

March 2003 (9 & d), Bayton

& Ranaivojaona 51, 52

(K!, MO!, TAN!); Toliara Prov.: Sakeny River plain,

July 1989, B. Du Puy et

al. 256 (K!, TAN!); unknown

date and locality,

Darian s.n. (BH!, K!);

HABITAT.

Riverine forest in lowv-lving

areas, particularly

on sandy or alluvial soils. Borassus madagascariensis

does not form

monospecific forest. It is common in

several towns in the northwest of

Madagascar, where

it

grows in

gardens, streets and on waste ground.

CONSERVATION STATUS. Vulnerable. Dransfield &

Beentje (1995a) assessed B. madagascariensis as

vulnerable (VU Alc) due to habitat loss and the

encroachment of human settlements. Subsequent

investigation by the author can only confirm this

assessment. Of all the species of

Borassus, this

one has

the smallest range.

While the species does not appear

to be threatened by over-exploitation, as are some

populations of B. aethiopum in

mainland Africa, all of

the populations visited by the author were in close

proximity to expanding human settlements. Some

populations are actually confined to urban areas

(Bayton et

al. 2003) and the decline in

habitat quality

qualifies this

species as vulnerable.

ETYMOLOGY.

The epithet 'madagascaniensis' translates

as 'of

Madagascar'.

VERNACULAR NAME. Dimaka (Sakalava). This name is

also used for

B. aethiopum in

Madagascar.

USES.

While several uses have been recorded for B.

madagascariensis Uumelle & Perrier de la Bathie

1913), Bayton et

al. (2003) could find little evidence

for

exploitation in the northwest of the island.

NOTES. The case for continued recognition of this

species has been difficult to assess. Most of the

taxonomic accounts dealing with Borassus

madagasca7iensis focus on differentiating it from the

other Madagascar species, B. sambiranensis. Borassus

madagascariensis has close affinities

with B. aethiopum.

This is

not entirely unexpected as East Africa is the

likely origin of the seeds that colonised M Iadagascar.

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A REVISION OF BORASSUS L. (ARECACEAE) 581

Both species are generally large in all aspects, and

both have a ventricose stem.

The differences between

the species are rather subtle and can be difficult to

interpret in the

herbarium. Borassus madagascariensis

has small petiole spines that are like saw-teeth

(Fig.1C), while the spines of B. aethiopum are large

and recurved (Fig. 1D - F). In B. madagascariensis, the

petiole remains green along its

entire length, in

both

high and low light environments. In B. aethiopum,

the

petiole is

yellow and turns

brown towards the stem. In

juvenile specimens of B. aethiopum, the petioles are

completely black (in full sun) or yellow-brown

(shade). Juvenile specimens of B. madagascariensis

have greenish-yellow petioles. The fruit apex of B.

madagascariensis is pointed and in this respect, it is

similar to that of Borassus akeassii.

The fruit apex of B.

aethiopum is flattened or depressed and an inverted

fruit

can sit

on its apex without toppling. The fruits

and seeds of B. madagascariensis are the largest in the

genus.

While the

colour characters can be difficult to

employ in the herbarium, the petiole spines are easily

identifiable. In combination with the large fruits

and

seeds, and a known origin in

Madagascar, this taxon

should be easily identified.

Jumelle and Perrier de la Bathie (1907, 1913) did

not cite a type specimen when describing B.

madagascariensis, so a neotype has been selected. The

neotype was collected in the town

of

Marovoay, at the

head of the Bay of Bombetok, which corresponds to

the locality

cited by

Bojer (1837: 308): "sur les

bords

de

la

7iviere

Marou-voai dans la baie de Bombetok".

Uncertain

Names

Borassus aethiopum

var. bagamensis Becc. (1914: 337).

Beccari (1924: 7). Type: Tanzania, Tanga Region,

Bagamoyo, Zimmerman

s.n. (holotype F!) .

Borassus aethiopum

var. senegalensis

Becc. (1914: 334).

Beccari (1924: 7). Type: Mali, Kayes Region: Kayes,

Chevaliers.n. (holotype FI!).

These taxa are separated from typical Borassus

aethiopum primarily by small variations in pyrene

morphology. The type specimens include no

vegetative material. The shape and size of a pyrene is

influenced primarily by the number of pyrenes that

develop in each fruit.

Within each species there is

considerable variation in fruit

and therefore pyrene

size and overlap between species is

common. It

was

for this reason that

Dransfield (1986a) chose not to

recognise var. senegalensis or var. bagamojensis, but

rather to

unite them under the name B. aethiopum.

However, with the recognition of a second species in

Africa, it is

possible that

one or both of the

varieties

of B. aethiopum could instead be attributable to B.

akeassii. Therefore it seems inappropriate to

synonymise

these names

at

present.

Specimens of Uncertain

Affinity

The following

African specimens

comprise

pyrenes

only and therefore cannot be confidently assigned to

either

African species.

BENIN. Unknown locality and date, Poisson s.n. (P!).

CAMEROON.

Unknown locality, 1923, Carolot s.n. (P!).

CENTRAL AFRICAN REPUBLIC. 16 km S of Koumbate

confluence with Pende, 5

May 1984, Fay s.n. (K!).

MALAWI.

Northern Region, Rumphi Distr., 6

miles W

of Rumphi, 6 Nov. 1977, Pawek 13220 (K!). MALI.

Unknown locality, 1937, Dubois 252 (P!); Foret

Baoule, 1937, Dubois 401146 (P!); Sikasso Region:

Ouassoulou, 1891, Chevalier s.n. (P!). NIGERIA.

Northern Nigeria, 1964, Tuley s.n. (K!). SUDAN.

Source

of the White Nile, 2 Feb. 1840, d'Arnaud s.n. (P!);

South Darfur State: Wadi Bullah, near Nyala, 5

May

1971, JLW 3136 (K!). TANZANIA.

Singida Region:

Lwumbu Valley, 21 Sept. 1927, Burtt 1659 (K!).

UGANDA. Unknown locality, 1955, Greenway s.n. (K!).

ZAMBIA. Lusaka Prov.: Chilanga Distr., Quien-Sabe

Farm, 1929, Sandwith s.n. (K!). UNKNOWN

COUNTRY.

West Africa, 1888, Tolly

158 (P!).

Excluded

Names

Borassus caudatus Lour. (1790: 619) = Arenga caudata

(Lour.) H. E. Moore (1960: 114).

Borassus dichotomus White (1839: 226) = Hyphaene

dichotoma (White) Furtado (1970: 301).

Borassus gomutus Lour. (1790: 618) = Arenga pinnata

(Wurmb.) Merr. (1917: 119).

Borassus ihur

Giseke (1792: 87) = Pholidocarpus ihur

(Giseke)

Blume (1847:

90).

Borassus machadonis Ridl. (1905: 203) = Borassodendron

machadonis (Ridl.) Becc. (1914: 361).

Borassus pinnatifrons

Jacq. (1797: 65) = Chamaedorea

pinnatifrons (Jacq.) Oerst. (1859: 14).

Borassus sonneratii

Giseke (1792: 88) = Lodoicea

maldivica

(J.

F.

Gmelin) Pers. ex

H. Wendl. (1878: 250).

Acknowledgements

Many thanks to Barbara Pickersgill, Bill Baker, John

Dransfield, Scott Zona and an anonymous referee for

their comments on the

manuscript. I am grateful to

the staff

and curators of

AAU, BH, BM, CANB, EA,

FTG, K, OUA, P and TAN for providing access to

specimens. Thank you to Lucy Smith (artwork) and

Justin Moat (map). Particular thanks to

Nicholas

Hind, Madeline Harley and Sue Mott. For assistance

with field

work, I thank Caleb Obunyali, Muthama

Muasya, Quentin Luke and the

National Museums of

Kenya (Kenya); Rolland Ranaivojaona, Helene

Ralimanana, Solofo Rakotoarisoa, Adam Britt and the

Parc Botanique et Zoologique de Tsimbazaza

(Madagascar); Amade Ouedraogo, Sita Guinko,

Joseph Boussim,

Paulin

Ouoba and the

Universite

de

C The Board

of Trustees of the

Royal Botanic Gardens,

Kew,

2007

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582 KEW BULLETIN VOL. 62(4)

Ouagadougou (Burkina Faso). This research was

completed as part of a Ph.D. scholarship funded by

the Natural Environment Research Council

(NER/S/A/2001/06315). Additional funding for

field

work was provided by the South Florida Palm

Society (Kenya), the International Palm Society and

the

Central Florida Palm Society (Madagascar), the

Montgomery Botanical Center, the Arthur Hosier

Travel Award Scheme and the School of Plant Ciow

Biological) Sciences of the University of Reading

(Burkina Faso).

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Abstract and Figures