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MORPHO-ANATOMICAL FEATURES OF CYPSELAS IN SOME SPECIES OF THE TRIBE COREOPSIDEAE (ASTERACEAE)

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Abstract

Cypselar morpho-anatomy is very helpfull for the separation of taxa in fruting stage. For this purpose, three species of the tribe Coreopsideae have been studied to separate the taxa more clearly. Morphologically, cypselas are either homomorphic {Bidens cernua and Cosmos sulphureus) or heteromorphic (Bidens pilosa). In Cosmos sulphureus, pappus is absent. Whereas in others, pappus is present. Pappus is represented by retrosely barbed awn-like structure. In Cosmos sulphureus, stylopodium is enlarged, knobe like structure whereas in the remaining, stylopodia are prominent but not enlarged. In cypselas, carpopodia are symmetric and carpopodial cells are arranged in 1-3 rows. Anatomically, in all die studied cypselas, phytomelanin layer is present in mesocarpic region but discontinuously developed, but except in Cosmos sulphureus where phytomelanin layer is continuous in rib region whereas in furrow region, it is discontinuous. Except in Cosmos sulphureus in other cypselas vellicular cavity exist. Testal layers are made up of crusted layers of parenchyma cells. Based on the aforesaid morpho-anatomical characters, an artificial key has been presented.
J. SWAMY BOT - CL. 31 : 67 - 72 (2014)
PRINTED IN INDIA. ALL RIGHTS RESERVED
MORPHO-ANATOMICAL FEATURES OF CYPSELAS IN SOME
SPECIES OF THE TRIBE COREOPSIDEAE (ASTERACEAE)
*BIDYUT KUMAR JANA AND SOBHAN KR MUKHERJEE
Taxonomy and Biosystematics Laboratory, Department of Botany,
University of Kalyani, Kalyani-741235, Nadia, West Bengal, India
Email
*
janabidyutkumar@yahoo.com, sobhankumar@yahoo.com
ABSTRACT
Cypselar morpho-anatomy is very helpfull for the separation of taxa in fruting stage. For this
purpose, three species of the tribe Coreopsideae have been studied to separate the taxa more clearly.
Morphologically, cypselas are either homomorphic {Bidens cernua and Cosmos sulphureus) or
heteromorphic (Bidens pilosa). In Cosmos sulphureus, pappus is absent. Whereas in others, pappus is
present. Pappus is represented by retrosely barbed awn-like structure. In Cosmos sulphureus, stylopodium
is enlarged, knobe like structure whereas in the remaining, stylopodia are prominent but not enlarged. In
cypselas, carpopodia are symmetric and carpopodial cells are arranged in
1-3
rows. Anatomically, in all die
studied cypselas, phytomelanin layer is present in mesocarpic region but discontinuously developed, but
except in
Cosmos
sulphureus where phytomelanin layer is continuous in rib region whereas in furrow region,
it is discontinuous. Except in Cosmos sulphureus in other cypselas vellicular cavity exist. Testal layers are
made up of crusted layers of parenchyma cells. Based on the aforesaid morpho-anatomical characters,
an artificial key has been presented.
Key words : Cypselar features, Coreopsideae, Asteraceae
INTRODUCTION
Among the 43 tribes of Asteraceae,
Coreopsideae consists of 30 genera and 550
species, distributed through out the globe
(Kadereit &
Jeffrey,
2007). Plants of
this
tribes
are usually annual or perennial herbs, sometimes
shrubs, rarely trees. In this tribe, cypselae may be
homomorphic or heteromorphic with sometimes
resin canals and winged. Pappus structures are
represented by either awn like structures or absent.
Several species of this tribe are very useful for
their horticultural potentiality. According to Panero
& Funk (2002) and Funk et
aL,
(2009), molecular
data of Heliantheae and related tribes support the
recognition of Coreopsideae at the tribal level. On
the basis of cypselar morpho-anatomical study,
the available literature of this tribe are almost
absent, although some species of this tribe
previously belonging to the tribe Heliantheae
have been studied (Mukheijee & Sarkar, 1998).
Now a days Coreopsideae has been recognized
as an independent tribe separated from the
tribe Heliantheae. The aims of this study is to
elaborate the detailed morpho-anatomical structure
of cypselas of studied species of
this
tribe.
MATERIALS AND METHODS
For the present study, dried, identified, mature,
cypselas were collected from one foreign
herbarium and also from the University of
Kalyani Campus and Sikkim, which are given in
the table 1. Table 1
Materials Sources
1. Bidens cernua L.
2. Bidens pilosa L.
3. Cosmos
sulphureus Cav.
Botanischer Garten der
Universitat Zurich, XXOZ-
19780082. 2008; Drawer
Gangtok, Sikkim, B. J.-16.
University of Kalyani
Campus. B. J.-12.
For morphological observation, cypselas were
softened by 4% NaOH solution. After that, they
were stained in aqueous safranin solution (0.1%) to
observe the different morphological parts with the
help of simple dissecting microscope (Model No.
363 01, Meopta, PRAHA, Made in Czechoslovakia).
For anatomical study, cross sections were done
BIDYUT KUMAR JANA AND SOBHAN KR MUKHERJEE
from the middle part of cypselas with the help of a
sharp razor blade to observe the different
anatomical region with the help of compound
microscope (Metzer).
RESULTS AND DISCUSSION
Bidens cernua
Morphology (Fig. 1 D-H)
Cypsela homomorphic, 9 x 1.5 mm including
pappus, 6 x 1.5 mm excluding pappus, black
brown, oblanceolate, straight, upper part truncate,
whereas lower part tapered. Ellipsoidal in cross
sectional configuration. Surface slightly pubescent
containing 4-5 ribs, alternating with furrow.
Furrows wider than the ribs. At the upper part of
cypsela, stylopodium present, prominent, enlarge,
partially immersed into the nectary. Pappus
represented by 4 unequally arranged, retrosely
barbed, pappus bristles yellow brown in colour. At
the basal region of cypsela, carpopodium present,
narrower than the base of cypsela, symmetric.
Carpopodial cells with thick-walled, elongated,
arranged in one row.
Anatomy (Fig. 2B)
Cypsela elliptic in cross section. Ribs present;
4-5 in number, conspicuous. Cypselar wall 0.12 mm
and 0.11 mm wide at ribs and furrow region
respectively. Pericarp thick, differentiated into two
zones- epicarp and mesocarp. Epicarp uniseriate,
made up of thin-walled, rectangular, compactely
arranged parenchyma cells, provided with thick
cuticle. Internal to the epicarp, mesocarp present;
made up of thin walled, elongated, compactely
arranged, parenchyma cells. Thickness of
mesocarpic parenchyma cells varies from 2-3 layers
in rib region and 4-5 cell layers in
furrow
region. In
each rib there is a small sclerenchyma brace which
is constituted by thick-walled, compactely arranged,
penta-hexagonal, sclerenchyma cells, containing
vascular trace. In between the parenchyma and
sclerenchyma cells, near each rib, phytomelanin
layer exists which is interrupted in some region.
Within the mesocarpic region, just below the rib,
vallecular cavity present. Testa attached with
cypselar wall, made up of crusted layer of
parenchyma cells. Endosperm persiste in mature
cypsela which is secondarily separated from testa
and is made up of uniseriately oriented thick-walled
parenchyma cells. Cotyledons two in number,
arranged at right angle to the axis of cypsela,
containing 10 resin ducts (5 ducts in each
cotyledon).
Bidens pilosa
Morphology (Fig. 1 I-L)
Cypsela heteromorphic. Ray cypsela 10 x
1
mm
including pappus, 7 x 1 mm excluding pappus,
black-brown, straight, linear. Disk cypsela 8x1 mm
including pappus, 5 x 1 mm excluding pappus,
black-brown, straight, linear. In disk cypsela,
surface glabrous whereas in ray cypsela surface
slightly pubescent. Surface containing ribs and
furrow. Furrows wider than the ribs. Upper part of
cypsela, stylopodium present, unenlarged, fully
immersed in the nectary. Pappus represented by
two, unequally developed, retrosely barbed awns,
yellow-brown in colour, 2-3 mm in length. At the
basal region of cypsela, carpopodium present,
symmetric, ring-like. Carpopodial cells thick-walled,
arranged in 2-3 rows.
Anatomy (Fig. 2C)
Cypsela narrow elliptic in cross section. Ribs
present; 8-10 in number, inconspicuous. Cypselar
wall 0.09 mm and 0.04 mm wide at ribs and
furrow region respectively. Pericarp thick,
differentiated in to three zones-epicarp, mesocarp
and endocarp. Epicarp uniseriate, made up of thin
walled, rectangular, compactely arranged,
parenchyma cells, provided with cuticle. Internal to
the epicarp, phytomelanin layer present;
discontinuously arranged. Internal to the epicarp,
mesocarp present; homogenous, made up of thick-
walled, pentangular, compactely arranged,
sclerenchyma cells containing vascular trace.
Sclerenchyma cells 2-3 cells wide at the
furrow and 9-11 cells wide at the rib region.
Internal to the mesocarp, endocarp present, made
up of thin-walled, rectangular, uniseriately oriented,
compactely arranged, parenchyma cells. Internal to
the endocarp, vallecular cavity present. Testa
attached with cypsela- wall, approximately
0.01
mm
thick, made up of crusted layer of parenchyma
cells. Endosperm persists in mature cypsela,
uniseriate, parenchymatous. Mature embryo
occupies a major part of the cypsela. Cotyledons
two in number, arranged at right angle to the axis
68
MORPHO-ANATOMICAL FEATURES OF CYPSELAS IN SOME SPECIES
of cypsela, containing 6 resin ducts (3 ducts in
each cotyledon).
Cosmos sulphureus
Morphology (Fig. 1 A-C)
Cypsela homomorphic, 8 x 1 nun, dark brown,
linear, slightly curved, tapered at both ends.
Quadrangular in cross section. Surface rough and
glabrous, margin dentate, containing 4 ribs,
alternating with furrow. Furrows wider than ribs.
Pappus absent. At the upper part of cypsela,
stylopodium present, enlarge, knobe-like, partially
immersed in the nectary. At the basal region of
cypsela, carpopodium present; symmetric,
quadrangular. Carpopodial cells with thick-walled,
arranged in one row.
Anatomy (Fig. 2A)
Cypsela quadrangular in cross section. Ribs
present; 4 in number, conspicuous. Cypselar wall
0.17 mm and 0.08 mm wide at ribs and furrow
region respectively. Pericarp thick, differentiated in
to two zones- epicarp and mesocarp. Epicarp
uniseriate, made up of thin-walled, rectangular,
compactely arranged, parenchymatous cells,
provided with cuticle. Internal to the epicarp,
phytomelanin layer present, discontinuously
arranged near the furrow region, whereas in ribs
region continuously arranged. Mesocarp
homogenous, made up of thick-walled, pentangular,
compactely arranged, sclerenchyma cells. In furrow
region thickness of sclerenchyma cells varies
from 3-4 cells, whereas in rib region it is 7-9
cells wide. Testa attached with cypselar wall,
approximately 0.01 mm thick, made up of crusted
layer of parenchyma cells. Endosperm persists in
mature cypsela, made up of thick-walled,
uniseriately arranged, parenchyma cells. Mature
embryo occupies a major part of the cypsela.
Cotyledons 2 in number, arranged oblique to the
axis of cypselas, containing 20 resin ducts (10
ducts in each cotyledon).
0.05 mm H, E
Figure 1. Morphology of studied cypselas
A-C. Cosmos sulphureus : A -Cypsela, B- Upper part of cypsela, C- Basal part of
cypsela; D-H. Bidens cernua
:
D- Cypsela, E- Surface hair, F- Basal part of cypsela, G-
Upper part of cypsela, H- Carpopodial cells; I-L. Bidens pilosa: I- Ray cypsela, J- Disk
cypsela, K- Upper part of cypsela, L- Lower part of cypsela.
69
BIDYUT KUMAR JANA AND SOBHAN KR MUKHERJEE
PI .
Scl .
Bar- 0.15mm.
Figure 2. Cross sections of studied cypselas
A- Cosmos sulphureus, B- Bidens cernua, C- Bidens pilosa
Abbrevations: Ep.- Epicarp, PL- Phytomelanin layer, Scl.- Sclerenchyma, Me.- Mesocarp, T.- Testa,
E.- Endosperm, V.T.- Vascular trace, V.C.- Vallecular cavity, Pa.- Parenchyma
Morpho-anatomical characters of cypselas of
three species of the tribe Coreopsideae have been
studied to separate them. Among the studied
cypselas, largest cypsela is present in the case of
Bidens pilosa (10 x 1 mm including pappus)
where as the smallest cypsela is present in case of
Cosmos
sulphureus (8 x 1 mm) . Shape of studied
cypselas varies from linear to oblanceolate.
Heteromorphism is seen in die case of cypsela of
Bidens pilosa, whereas remaining studied cypselas
are homomorphic. Homomorphism is also present in
another species (Bidens frondosa) of this tribe
(Jana and Mukherjee, 2012). Colour of cypselas is
not an important distinguishing character and is
not helpful in the separation of taxa, more clearly.
In the case of Bidens pilosa, disk cypsela is
glabrous whereas ray cypsela is pubescent. In
Bidens cernua, surface is slightly pubescent. In
Cosmos sulphureus, surface is rough and glabrous.
Among the studied cypselas, in Cosmos
sulphureus, pappus is absent, whereas in the
remaining studied cypselas, pappus are present
and which are retrosely barbed type. Mukherjee
and Sarkar (2008), have indicated the pappus
structures in some tribes of the Asteraceae. There
are two opinions on the origin of pappus. These
are non-calycine (Small, 1919) or calycine (Lund,
1872) nature of pappus. The universally accepted
view is that the pappus is calycine in nature, i.e.,
develop from the modified calyx. At fee upper part
of cypsela, stylopodium is present. It is the
modified style base with associated nectaries. In
Cosmos sulphureus and Bidens cernua, stylopodia
are prominent and enlarged whereas in other
species, stylopodium is unenlarged and is not
prominent. Mukherjee (2005) has studied the
stylopodial characters of some members of
Asteraceae. Carpopodia are basal in position. In
all the studied cypselas, carpopodial cells varies
from
1-3
rows. Actually carpopodium is the basal,
meristematic zone of cypsela (Mukherjee and
Nordenstam, 2004) and it helps in the detachment of
cypselas from the thalamus. Except the cypsela of
Cosmos sulphureus, the remaining studied cypselas
are elliptical in cross sectional configuration. In all
the studied cypselas, phytomelanin layers are
present in mesocarpic region. Phytomelanin is
found as continuous layer in ribs regions of
Cosmos sulphureus, but exists as discrete bundle
in furrow regions. In Bidens cernua and B. pilosa,
it is found as discrete bundle. Phytomelanin is
deposited just inside the epidermis in Cosmo*
sulphureus and Bidens pilosa, whereas it is
found in deeply situated tissue in Bidens
cernua. The presence of phytomelanin layer has
been indicated in some species (Helianthus
70
MORPHO-ANATOMICAL FEATURES OF CYPSELAS IN SOME SPECIES
annuus, Xanthium pungens, etc.) of the tribe
Heliantheae (Mukherjee and Sarkar, 1998).
Actually phytomelanin is secreted by the glandular
activity of hypodermal cells (Pandey, 1989). In
Cosmos sulphureus, vallecular cavity is absent but
present in other studied species. Testa is made
up of, crusted layers of parenchyma cells. Resin
ducts variy from 3-10 in each cotyledon; 3 in
Bidens pilosa, 5 in B. cernua and 10 in Cosmos
sulphureus.
CONCLUSION
On the basis of the above characters, it can be
concluded that replete the members of the tribe
Coreopsideae are with grait variations of
morphological and anatomical characters of
cypselas. These features are admixture of both
primitive and advanced features. So the tribe,
Coreopsideae can be regarded as heterobathmic
in nature.
ARTIFICIAL KEY TO CYPSELA
la. Cypsela heteromorphic; pappus 2, retrosely
barbed awns; carpopodial cells 2-3
layers Bidens pilosa
lb. Cypsela homomorphic; pappus absent or
represented by 4 retrosely barbedawns;
carpopodial cells 1 layer (2)
2a. Pappus present; vellicular cavity present;
resin ducts 5 in each cotyledon;
phytomelanin layer hypodermal in
origin Bidens cernua
2b. Pappus absent; vellicular cavity absent;
resin ducts 10 in each cotyledon;
phytomelanin layer subepidermal in
origin Cosmos sulphureus
ACKNOWLEDGEMENTS
We are thankful to Dr. Peter Enz, Curator,
Botanischer Garten der Universitat Zurich, Zurich,
Switzerland, for sending mature, identified seeds,
for this study.
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71
... This is a complex unilocular, dry, indehiscent fruit attached to the pericarp by the funicle, originating from an inferior ovary and wind-dispersed (Marzinek et al., 2008;Jeffrey, 2009;Judd et al., 2002). Cypselae are usually elongate with variable or glabrous indument, with or without pappus, ribbed or smooth (Roth, 1977;Jana and Mukherjee, 2014). Its variable anatomical characters include the orientation of cells in the exocarp and mesocarp, the presence or absence of a phytomelanin layer, calcium oxalate crystals in the mesocarp, and different cells forming the testa and resin ducts (Roth, 1977;Jana and Mukherjee, 2014). ...
... Cypselae are usually elongate with variable or glabrous indument, with or without pappus, ribbed or smooth (Roth, 1977;Jana and Mukherjee, 2014). Its variable anatomical characters include the orientation of cells in the exocarp and mesocarp, the presence or absence of a phytomelanin layer, calcium oxalate crystals in the mesocarp, and different cells forming the testa and resin ducts (Roth, 1977;Jana and Mukherjee, 2014). ...
... They are smooth to striate, with or without wings and the pappus is inconspicuous, 2-15 when present, with smooth or barbed bristles or awns (Crawford et al., 2009). Previous studies of morphological and anatomical traits in the tribe Coreopsideae have revealed important features of taxonomic importance in Bidens, Coreopsis, Cosmos, Dahlia, Fitchia, Glossocardia, and Moonia (Pandey and Singh, 1982;Tadesse et al., 1995;Julio and Oliveira, 2009;Jana and Mukherjee, 2014;Pandey et al., 2014;Tadesse and Crawford, 2014;Batista and De Souza, 2017;Souza-Filho et al., 2019;Mathur and Pandey, 2020). These studies corroborate the importance of morphological and anatomical traits of the cypselae at the genus or even species level. ...
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ABSTRAC T Acomparativestudyofmorphologyandanatomyofmaturecypselasin14 speciesbelongingto10genera,suchasBIDENS,CHRYSANTHELLUM,COREOPSIS, COSMOS,ECHINACEA,GADXARDIA,GLOSSOGYNE,HELIANTHUS,TITHONIAandXANTHTUM underthetribeHeliantheae(Asteraceae)wasundertakenunderlightandscani...ig electronmicroscopes.Morphologicallytheformandstructureofcypselas, carpopodiaandpappusarediacriticalforcharacterizationoftaxa.Inallspecies pericarpiswelldifferentiatedinto2zones.Cellsoftheepicarpareusually tangentiallyelongated,providedwithyelloworbrownsubstances.Mesocarpis mainlydifferentiatedinto4zones.Numberanddistributionofvasculartraces, phytomelanlayerandsecretorycavitiesaretaxonomicallysignificantincertain taxa.Anartificialtaxonomickeyusingthedetailedmorphological,anatomical andSEMobservationsonthematurecypselasareprovided. KeyWords:Asteraceae-Heliantheae-Morphology-Anatomyofcypseias.
Article
Molecular studies of the flowering plant family Compositae (Asteraceae) based on comparative DNA sequence data of chloroplast genes provide new insights into the evolution and radiation of the family. The results support the creation of new groups to maintain a classification that reflects evolutionary history. We are proposing the following new names: subfamilies Corymbioideae, Gochnatioideae, Gymnarrhenoideae, Hecastocleoideae, and Pertyoideae; tribes Athroismeae, Corymbieae, Dicomeae, Gochnatieae, Gymnarrheneae, Hecastocleideae, Polymnieae; subtribe Rojasianthinae. The totals now stand at 11 subfamilies and 35 tribes. Only one tribe, the Mutisieae, is non-monophyletic having two branches. Most of the new groups are derived from taxa included in tribe Mutisieae, long suspected to be a paraphyletic group. Molecular studies that support these changes are discussed elsewhere but a summary of their results is presented.
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  • S Lund
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Phytomelanin-Heliantheae
  • A K Pandey
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