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Zhengyia shennongensis: A new bulbiliferous genus and species of the nettle family (Urticaceae) from central China exhibiting parallel evolution of the bulbil trait

Authors:
  • Honam National Institute of Biological Resouces
  • Kunming Institute of Botany-Chinese Academy of Sciences

Abstract and Figures

Zhengyia shennongensis is described here as a new genus and species of the nettle family (Urticaceae) from Hubei province, central China. The phylogenetic position of Z. shennongensis is determined using DNA sequences of nuclear ribosomal ITS and three plastid regions (rbcL, psbA-trnH, trnL-F). Zhengyia shennongensis is readily distinguished from the related genera Urtica, Hesperocnide, and Laportea in the tribe Urticeae by its seed (oblong-globose or subglobose and not compressed achenes, surface densely covered with nipple-shaped protuberances) and stipule morphology (large leaf-like stipules with auriculate and amplexicaulous base and united with stem). Phylogenetic evidence indicates that Zhengyia is a distinct group related to Urtica (including Hesperocnide) species and Laportea cuspidata in tribe Urticeae. The bulbiliferous species of the tribe (L. bulbifera, L. cuspidata, Z. shennongensis) do not form a clade. This result indicates that the bulbil trait evolved in parallel within Urticeae. Our findings highlight the importance of shady and moist habitats in promoting species diversification and the parallel evolution of morphological traits that are likely to be adaptive.
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INTRODUCTION
Urticeae (= Urerareae Wedd.) is a moderately sized tribe
of the nettle family (Urticaceae) with eleven genera and ap-
proximately 220 species. Its members are often found in humid
habitats in forests or at forest margins and occur in both the
Old and New Worlds (Friis, 1993; Hadiah & al., 2008; Cohn
& Hadiah, 2009). The tribe is characterized by stinging hairs
and pistillate flowers with four tepals, of which frequently one
pair is larger than the other, and without staminodes (Friis,
1989, 1993). Because of the obvious morphological synapo-
morphies of Urticeae, it is not difficult to recognize a plant as
being a member of this tribe. Moreover, phylogenetic analysis
of Urticaceae using plastid DNA sequence data has shown
that Urticeae (including Poik ilospermum Zipp.) form a well-
supported clade (Hadiah & al., 2008).
The Shennongjia National Nature Reserve (SNNR) is lo-
cated in the Northwest of Hubei province, central China. Its
unique geographical location and complex topology make it
one of the most biodiverse areas in China (Ying, 2001; Xie,
2003). The Shennongjia Mountains are characterized by high
mountains and deep valleys, a dense network of streams, and
lush vegetat ion. The region is an impor tant hot-spot for south-
central Chinese biodiversity and contains many endemic plants
(Myers & al., 2000). During our recent in-depth floristic ex-
plorations of the SNNR, an unusual taxon caught our attention.
The plant was easily identified as belonging to Urticeae based
on the presence of stinging hairs, stipules, and pistillate f low-
ers with four tepals and without staminodes. In its paniculate
inf lorescences with many long branches and its four-lobed
perianth with larger dorsal than ventral lobes in its female
flowers, it superficially resembles Urtica L., a genus of about
30 species with a wide distribution in the northern temperate
region (Chen & al., 2003). However, based on its alternate leaf
arrangement, the presence of one to three woody bulbils in
sterile axils, intrapetiolar stipules in the leaf axils, and oblique
achenes with short stipes, we initially assigned the new taxon to
Laportea Gaudich., a genus with 30 species confined to tropical
and warm-temperate E Asia and eastern North America (Friis,
1993). Upon closer examination, however, it was clear that the
set of morphological characters did not match Urtica, Laportea
or any other genus of Urticeae (Table 1). The plant is described
below as a new genus with only one species, Zhengyia shen-
nongensis T. Deng, D.G. Zhang & H. Sun.
Bulbils are specialized propagules, allowing vegetative
reproduction and dispersal, and many herbaceous plants can
produce them (Wang & al., 2004; Walck & al., 2010). Pres-
ence or absence of bulbils has been recognized as a significant
Zhengyia shennongensis: A new bulbiliferous genus and species of
the nettle family (Urticaceae) from central China exhibiting parallel
evolution of the bulbil trait
Tao Den g,1,2,5 Changkyun Kim,1,5 Dai-Gui Zhang,3 Jian-Wen Zhang,1 Zhi-Ming Li,4 Ze-Long Nie1 & Hang Sun1
1 Key Laboratory of Biodiversity and Biogeography, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201,
Yunnan , P.R. China
2 University of Chinese Academy of Sciences, Beijing 100039, P.R. China
3 Key Laboratory of Plant Resources Conservation and Utilization, Jishou University, College of Hunan Province, Jishou 416000,
Hunan, P.R. China
4 Life Science School, Yunnan Nor mal Universit y, Kunming 650031, Yunnan, P.R. China
5 These authors contributed equally to the work.
Author for correspondence: Hang Sun, hsun@mail.kib.ac.cn
Abstract
Zhengyia shennongensis is described here as a new genus and species of the nettle family ( Urticaceae) from Hubei
province, central China. The phylogenetic position of Z. shennongensis is determined using DNA sequences of nuclear ribo-
somal ITS and three plastid regions (rbcL, psbA-trnH, trnL-F). Zhengyia shennongensis is readily distinguished f rom the
related genera Urtica, Hesperocnide, and Laportea in the tribe Urticeae by its seed (oblong-globose or subglobose and not
compressed achenes, surface densely covered with nipple-shaped protuberances) and stipule morphology (large leaf-like
stipules with auriculate and amplexicaulous base and united with stem). Phylogenetic evidence indicates that Zhengyia is a
distinct group related to Urtica (including Hesperocnide) species and Laportea cuspidata in t ribe Urticeae. The bulbiliferous
species of the tr ibe (L. bulbifera, L. cuspidata, Z. shennongensis) do not form a clade. This result indicates that the bulbil trait
evolved in parallel within Urticeae. Our findings highlight the importance of shady and moist habitats in promoting species
diversification and the parallel evolution of morphological traits that are likely to be adaptive.
Keywords
bulbils; central China; new genus and species; parallel evolution; Urticaceae; Urticeae; Zhengyia shennongensis
Received: 14 May 2012; revision received: 1 Oct. 2012; accepted: 12 Nov. 2012.
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morphological trait in species delimitation in Urticeae (Chen
& al., 2003). The character is also useful to establish infra-
generic taxa in genera of Urticeae (e.g., Laportea; Chen & al.,
2003). To date, in Urticeae only two species of Laportea
(L. bulbifera Weed ., L. cuspidata Friis) have been reported
to be bulbiliferous; they both grow in shady, moist conditions
(Chen & al., 2003).
In the present study, we determine the phylogenetic
position of the new taxon based on morphological data, espe-
cially surface features of the achene examined using scanning
electron microscopy (SEM), and cytological and molecular data
(the three plastid regions rbcL, psbA-trnH intergenic spacer
[IGS], and trnL-F IGS; and nuclear ribosomal ITS [nrITS]).
Based on the inferred phylogeny, we also provide a discussion
of the evolution of the bulbil trait in Urticeae.
MATERIALS AND METHODS
Plant material. —
Samples of Z. shennongensis were col-
lected for morphological comparison from the only known
populatio n—Wusha nhu, Hub ei Provi nceduri ng our field in-
vest ig at ions in 2011 (Fig. 1). Leave s and mat u re seed s were also
collected for SEM and cytological and molecular phylogenetic
studies. For comparison with the seed morphology of Z. shennon-
gensis, eight species of the closely related U. mairei H. Lév, U. di-
oica L., U. fissa E. Pritz., U. urens L., L. bulbifera Wed d., L. cus-
pidata Friis, L. canadensis Gaudich., and Girardinia diversifolia
(Link) Friis were examined.
In order to determine phylogenetic relationships in Urticeae
using molecular markers, we sampled 16 taxa (21 accessions)
in addition to Z. shennongensis, including two species of Den-
drocnide Miq. (two ac cessions), thre e subspecie s of Girardinia
diversifolia (three accessions), one species of Hesperocnide
Torr. (one accession), three species of Laportea (five acce s-
sions), one species of Poikilospermum (one accession), and
six species of Urtica (nine accessions). We also included three
species, Pilea plataniflora C.H. Wright of Elatostemateae
Gaudich., Boehmeria spicata Thunb. of Boehmerieae Gaudich.,
and Fatoua villosa Nakai of Moraceae as outgroups, based on
a previous phylogenetic analysis using rbcL and trnL DNA
sequence data (Hadiah & al., 2008). Voucher information and
GenBank accession numbers for all specimens used in this
study are listed in Appendix 1.
Seed observation. —
The mature seeds of 90 individuals
of the species listed above and our new taxon were mounted
on aluminum stubs with double-sided adhesive tape, sputter-
coated with gold to a maximum thickness of 20 μm, and ex-
amined using a KYKY-1000B scanning electron microscope
(SEM; Science Instrument Company, Beijing, China) with a
voltage of 30 kV. Microphotographs focused primarily on the
center of the seeds. Seed morphology was also examined under
the dissecting microscope (OLYMPUS BX53).
Cytological studies. —
Root-tip meristems were obtained
by germinating seeds on wet filter paper in Petri dishes at ap-
proximately 20°C. Root tips less than 1.5 cm long were cut and
treated with 0.002 M 8-hydroxyquinoline at room temperature
for 3–5 h before being fixed in Carnoy (glacial acetic acid:
absolute ethanol = 1 : 3), macerated in a 1 : 1 mixture of 45%
acetic acid and 1 M HCl for 2.5 min, and stained and squashed
in Carbol Fuchsine. Karyotypes of mitotic chromosomes at
metaphase were determined from at least f ive well-spread
Fig. 1.
Distribution of Zhengyia
shennongensis T. Deng, D.G.
Zhang & H. Su n. The circle indi-
cates the t ype locality of Z. shen-
nongensis.
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metaphases of three different roots. The designation of the
centromere position as median (m), submedian (sm) and sub-
terminal (st) followed Levan & al. (1964).
DNA extraction, PCR amplification, and sequencing. —
Total genomic DNA was isolated from silica gel-dried leaf
material using the Universal Genomic DNA Extraction Kit
(Takara, Dalian, China). Primer sets and protocols for PCR
followed specifications in previous publications: rbcL (prim-
ers Z1 and 1204R; Zurawski & al., 1981; from G. Zurawski
[DNAX Research Institute, Palo Alto, California, U.S.A.]),
psbA-trnH IGS (psbA_F and trn H _R; Hami lton, 1999), trnL-F
IGS (e and f; Taberlet & al., 1991), and nrITS (ITS1 and ITS4;
White & al., 1990; Kim & al., 2010). Amplif ied DNA samples
were analyzed by electrophoresis on 1.4% agarose gel, run in
a 0.5× TBE buffer and detected by ethidium bromide staining.
The PCR products were then purified using a QiaQuick gel
extraction kit (Qiagen, Inc., Valencia, California, USA) and
directly sequenced in both directions using the amplification
primers on an ABI 3730 automated sequencer (Applied Bio-
systems, Forster City, California, U.S.A.).
Phylogenetic analyses. —
DNA Baser v.3 (http://www
.dnabaser.com) was used to evaluate the chromatograms for
base confirmation and to edit contiguous sequences. Multiple-
sequence alignment was performed with MAFFT v.6 (Katoh
& al., 2009; available at http://www.genome.jp/tools/mafft)
using the default alignment parameters. Gaps were coded as
missing data. All datasets have been submitted to TreeBASE
(http://www.treebase.org/; study accession number, S12631).
The phylogenetic reconstruction of the sequences was
performed by maximum parsimony (MP) in PAUP* v.4.0b10
(Swofford, 2002). All characters were weighted equally and
unordered. Each dataset was analyzed separately and then a
simultaneous analysis was performed including all four re-
gions. Before combining the datasets, the incongruence length
difference (ILD) test was conducted to assess data congruency
(Farris & al., 1995) using PAUP* and 10,000 heuristic search
replications including only parsimony-informative characters.
Most parsimonious trees were searched with a heuristic al-
gorithm using tree bisection-reconnection branch swapping,
MULPARS, and the alternative character state. Strict con-
sensus trees were constructed from the most parsimonious
trees. Bootstrap analyses (BP; 1000 pseudoreplicates) were
conducted to examine the relative level of support for individual
clades (Felsenstein, 1985). The consistency index (CI; Kluge
& Farris, 1969) and retention index (RI; Farris, 1989) were
calculated to measure the amount of homoplasy in the dataset.
Phylogenetic analyses of the nrITS and combined data sets
were also conducted using Bayesian Markov chain Monte Carlo
(MCMC) infere nce (BI; Yang & Ranna la , 1997 ) using MrBayes
v.3.12 (Ronqu ist & Huelsenbe ck, 2003). Modelte st v.3.1 (Posa da
& Crandall 1998) was used to determine the optimal model
of DNA evolution for the data based on the Akaike informa-
tion criterion (AIC; Akaike, 1974). Four chains of the MCMC
inference were run simultaneously, with sampling every 100
generations over a total of one million generations. The first
2500 trees (25%) of the sample trees from each run were dis-
carded as determined by Tracer v.1.5 (Rambaut & Drummond,
2007). A Bayesian consensus tree was constructed from the
remaining trees, yielding the posterior probability (PP) values
for each clade.
The single most parsimonious topology obtained from the
analysis of the combined molecular data (nrITS and three plas-
tid DNA regions) was employed to reconstruct the evolution of
the bulbil character. Character reconstruction was carried out
under the assumption of unordered and unweighted character
states with the Ancestral State Reconstruction Package in Mes-
qu it e v.2.75 (Ma ddiso n & Ma ddi son, 2011) using unambigu ou s
optimization.
RES U LT S
Morphological characters. —
Morphological characters
of Z. shennongensis and related genera, including Dendro-
cnide, Girardinia, Hesperocnide, Laportea, Poikilospermum,
and Urtica, are list ed in Table 1. The se ed char act eri st ics of our
new taxon, including shape and surface sculpturing, were found
to be unique when compared to the other genera. The achene
shape of Z. shennongensis was oblong-globose or subglobose
and extremely asymmetrical, and no infraspecific variation
was found (Fig. 2A). The seed surface of Z. shennongensis is
densely covered with nipple-shaped protuberances but smooth
and/or verrucose in the other genera (Fig. 2).
Chromosome counts and karyomorphology.
The ch r o -
mosome number in mitotic metaphase cells was found to be
2n = 24, and the karyotype formula is 2n = 6m + 16sm + 2st
(Fig. 3).
Phylogenetic analyses. —
The characteristics and sta-
tistics for nrITS, the three plastid regions, and the combined
data sets for the MP analyses are presented in Table 2. Bayesian
analyses of all datasets resulted in the same tree topologies
as the corresponding MP analyses (data not shown). All MP
trees were generally congruent with respect to well-supported
clades, but there was an incongruence between the plastid and
nrITS analyses concerning the position of Z. shennongensis.
The combined plastid analysis resolved both Z. shennongensis
samples as well-supported sister to Urtica and Hesperocnide
species (BP = 92%, PP = 1.00), whereas in the nrITS tree the
species was sister to a clade including Urtica, Hesperocnide,
and Laportea species but with low statistical support (BP =
50%, PP = 0.64; data not shown).
ILD tests failed to identify significant conf lict among the
th ree partition s of the plasti d dat aset (rbcL, psbA-trnH, trnL-F;
P = 0.065) and between the nrI TS and the plas tid data sets (P =
0.052). When all molecular datasets were combined, the single
MP tree found was better resolved than any tree from sepa-
rate analyses. Phylogenetic analysis of the combined dataset
resulted in a single most parsimonious tree (tree length = 2302,
CI = 0.597, RI = 0.756). In the MP tree, tribe Urticeae formed
a monophyletic group (BP = 100%, PP = 1.00; Fig. 4). The two
individuals of Z. shennongensis were sister to Urtica (includ-
ing Hesperocnide) species, wit h high statistical support (BP =
92%, PP = 1.00). Laportea cuspidata was sister to the clade
comprising Zhengyia and Urtica + Hesperocnide sp ecies (BP =
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86% , PP = 1.00). The bulbilifer ous spe cies (L. bulbifera, L. cus-
pidata, and Z. shennongensis) were not closely related to each
other (Fig. 4).
DISCUSSION
Systematic position of Zhengyia shennongensis. —
Ac-
cording to the classification of Urticaceae by Friis (1989, 1993),
our new taxon Z. shennongensis is a member of tribe Urticeae.
In tribe Urticeae, the basic chromosome number most often
is x = 12 and 13, and less often x = 10, 11, and 19 (e.g. Wood-
land & al., 1976, 1982; Friis, 1993). The chromosome number
of Z. shennongensis was found to be 2n = 24 (x = 12) in this
study (Fig. 3). Thus, cytological evidence supports that our
new species should be included in Urticeae. Moreover, our
molecular phylogenetic results clearly confirmed that Z. shen-
nongensis is part of Urticeae (Fig. 4).
In general, genera of Urticeae have been recognized
primarily on the basis of stipule and fruit shape (Friis, 1993;
Chen & al., 2003). Zhengyia shennongensis has a distinctive
oblong-globose or subglobose achene with dense nipple-shaped
Table 1.
Morphological comparison of Zhengyia with other genera in Urticeae.
Character Zhengyia Dendrocnide Girardinia Hespero cnide Laportea I
d
Laportea II
e
Poikilo-
spermum Urtica
Habit
a,b
robust herb shrub robust herb herb herb herb shrub or
woody
climber
herb
Bulbils
a,b
present absent absent absent present absent or
present in
L. bulbifera
absent absent
Leaf arrangement
a,b
alternate alternate alternate opposite alternate alternate alternate opposite
Stipules
a,b
intrapetiolar,
auriculate-
amplexicau-
lous base
united with
the stem,
persistent
intrapeti-
olar, subulate
or linear,
deciduous
intrapeti-
olar, subulate
or linear,
deciduous
lateral, subu-
late or linear,
persistent
intrapeti-
olar, subulate
or linear,
deciduous
intrapeti-
olar, subulate
or linear,
deciduous
intrapeti-
olar, subulate
or linear,
deciduous
lateral, subu-
late or linear,
persistent
Perianth
a
deeply
4-lobed, one
pair larger
4-lobed,
lateral ones
slightly larger
ovoid-
tubular, (2–)
3-toothed
almost tubu-
lar, minutely
2-toothed at
the apex
4-lobed,
strongly un-
equal, lateral
larger
4-lobed, one
minute or
absent
clavate-
tubular
deeply
4-lobed, one
pair larger
Inflorescences pairs solitary solitary or
pairs
pairs solitary solitary solitary pairs
Stigmas
a,b
short clavate linear or
ligulate
subulate,
acute, minute
capitate-
penicillate
linear, papil-
lose on one
side
linear, papil-
lose on one
side
capitate or
ligulate
capitate-
penicillate
Achene symmetry
a,b
asymmetric asymmetric asymmetric symmetric asymmetric asymmetric asymmetric symmetric
Achene shape
a
oblong-
globose or
subglobose,
not com-
pressed
elliposidal
to ovoid,
compressed
broadly
ovoid,
compressed
ovate,
compressed
ovoid to
semicircular,
compressed
ovoid to
semicircular,
compressed
oblong, ellip-
soid or ovoid,
compressed
ovoid,
compressed
Achene surface
a,c
with dense
nipple-shaped
protuberances
verrucose verrucose unknown smooth smooth or
with stripes
verrucose smooth or
verrucose
with sunken
dots
a
Friis (1993) and Chen & al. (2003).
d
Laportea I includes L. cuspidata.
b
Based on herbarium collections and field observation.
e
Laportea II comprises two species (L. bulbifera, L. interrupta).
c
Based on SEM.
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protuberances on the surface (Fig. 2A). The species also differs
from other genera of Urticeae by having large leaf-like stipules
with an auriculate-amplexicaulous base united with the stem
(Figs. 4, 5E). These differences are reflected in the MP tree
using the combined dataset where the new genus occupies a
distinct position in Urticeae with maximum support (BP =
100%, PP = 1.00; Fig. 4). Therefore, the recognition of Zhengyia
at the rank of genus is warranted based on morphological and
molecular evidence.
Our phylogenetic analyses showed that H. tenella Tor r.
was nested in the Urtica clade. This close relationship is
morphologically supported by opposite leaves, lateral stipules,
and straight achenes (Table 1). Zhengyia shennongensis is clos-
est relative of the Urtica + Hesperocnide clade with high sup-
port (BP = 92%, PP = 1.00; Fig. 4). Several morphological
characters (e.g., herbs with persistent stipules, deeply 4-lobed
perianth, inflorescences with many long branches) support
these relationships. Within this clade, Z. shennongensis can
be easily distinguished from Urtica and Hesperocnide species
by its alternate leaf arrangement (vs. opposite), large stipules
inserted in the axil of leaves (vs. 2 or 4 rather small and nar-
row, lateral stipules), and extremely oblique achenes (vs. erect;
Table 1; Fig. 4).
Our molecular data do not support the monophyly of
Laportea. Laportea cuspidata (Laportea I) is a sister to the
Zhengyia + Urtica (including Hesperocnide) lineage but not to
the other species of Laportea (Laportea II; Fig. 4). Zhengyia
shennongensis with one to three woody bulbils in sterile leaf
axils (Fig. 5F) resembles L. cuspidata, and these two species
share other morphological characters such as alternate leaves
and oblique achenes. However, the stigma of Z. shennongen-
sis is short and clavate, while that of L. cuspidata is linear
(Table 1). In addition, the achene surface of Z. shennongensis
differs from that of L. cuspidata in having markedly nipple-
shaped protuberances (Fig. 2A, G).
Of the other genera in tribe Urticeae, Z. shennongensis is
similar to Girardinia in that both are robust herbs with long
stinging hairs (> 5 mm). However, Z. shennongensis is distin-
guished from Girardinia by three morphological characters:
the presence of bulbils in leaf axils, branched inflorescences,
and the ornamentation of the achene surface (Table 1; Fig. 4).
Zhengyia shennongensis can be easily distinguished from
Dendrocnide and Poikilospermum by habit (herbs vs. shrub
or trees). Moreover, our molecular evidence shows that Z. shen-
nongensis is not closely related to Girardinia, Dendrocnide,
and Poikilospermum (Fig. 4).
Parallel evolution of bulbils. —
Many herbaceous plants
form bulbils (Okagami, 1979). Bulbils serve as a means of
clonal reproduction with the ability to colonize and seques-
ter resources quickly after initial introduction, particularly
in isolated populations (Callaghan & al., 1997; Abrahamson,
1980). Although bulbils are a valuable reproductive propert y,
they are found in only three species (L. bulbifera, L. cus-
pidata, Z. shennongensis) of Urticeae. In the combined MP
tree, the three bulbiliferous species did not group together
but were placed in three different clades, each with maximal
support except L. bulbifera (BP = 57%, PP = 0.79; Fig. 4). Two
Fig. 2.
Comparison of achene morphology and surface sculpting in
tribe Urticeae.
A,
Zhengyia shennongensis (Deng, Zhang & Sun 3431;
KUN);
B,
Urtica mairei (Pen g 16 07; KUN);
C,
U. dioica (Ca i 55102;
KUN);
D,
U. fissa (Liu 16628; KUN);
E,
U. urens (Qingzhang Exped.
318; KUN);
F,
Laportea bulbifera (Zhangdian Exped. 2575; KUN);
G,
L. cuspidata (Qingzhang Exped. 13367; KUN );
H,
L. canadensis
(Ko ya m a 74 01; KUN);
I,
Girardinia diversifolia (Nie & Deng 4248;
KUN).
a,
Dissecting microscope;
b,
SEM, low magnification;
c,
SEM,
ultrastructure of seed surface.
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reconstr uctions of bulbil evolution are equally parsimonious
in our phylogenetic tree (Fig. 4). Either bulbils evolved three
times independently in Urticeae or they evolved twice and
were lost once.
Bulbils have been recorded in many families and also in
different clades of single tribes (Givnish & al., 2000; Wang
& al., 200 4; Thomas & al., 2005; Kit aha ra & al., 2010) and may
have originated in response to strong selection in shady, moist
and pollinator-poor habitats (Wake & al., 2011), and indeed the
three bulbiliferous species of Urticeae grow mainly in shady
habitats along creeks, particularly on wet, dripping cliffs in
valley s. Th is tr ait probably re pl aces pr opagation and di spersal
by seeds or fruits. When compared with species without bul-
bils (e.g., Urtica, Girardinia), the bulbil iferous taxa appear to
have less seed set as judged from our field observations and
herbarium material, but statistical confirmation of this obser-
vation would require more detailed measurement. It might be
that the wind-pollinated bulbiliferous taxa of Urticeae have
evolved these propagules to cope with lack of seed set in the
windless conditions of their extremely shady, humid habitats.
Alternat ively, the bu lbils, which may be dispe rsed by grav it y,
water, animals, or birds (Thomas & al., 2005; Mizuki & Taka-
ha shi, 20 09), may be bet ter suited for sha dy ha bitats tha n seeds
because they are much larger than normal seeds of Urticaceae
and may store more nutrients needed for establishment.
TAXONOMIC TREATMENT
Zhengyia shennongensis T. Deng, D.G. Zhang & H. Sun, gen.
& sp. nov. – Holotype: China, cent ral China , Hubei prov-
ince, Shennongjia Forest District (SNNR), Yangri town,
Wushanhu, 31°32′37″ N, 110°50′35″ E, 450 m alt, 4 Sep
2011, T. Deng, D.G. Zhang & H. Sun 2295 (KU N; iso type s:
A, K, MO, PE). Figures 5 and 6.
Description. – Perennial robust herbs with long stinging
hairs. Rhizomes stoloniferous, up to 2 m long. Stems erect,
1–3 m tall, terete, not longitudinally angular or sulcate, slightly
Table 2.
Tree statistics for the nrITS, rbcL, psbA-trnH, trnL-F, and combined datasets from maximum parsimony (MP) analysis.
Parameters nrITS rbcL psbA-trnH trnL-F
Combined
ptDNA nrITS+ ptDNA
Number of sequences (ingroup/outgroup) 26 (23/3) 26 (23/3) 26 (23/3) 26 (23/3) 26 (23/3) 26 (23/3)
Aligned length [bp] 744 1013 337 426 1776 2520
Variable characters (%) 427 (57.4) 160 (15.8) 225 (66.8) 178 (41.8) 563 (31.7) 990 (39.3)
Parsimony informative characters (%) 307 (41.3) 87 (8.6) 131 (38.9) 113 (26.5) 331 (18.6) 638 (25.3)
Number of trees (MP) 186821
MP tree length 1169 260 537 303 1117 2302
Consistency index (CI)
a
0.577 0.591 0.623 0.727 0.632 0.597
Retention index (RI) 0.743 0.809 0.707 0.878 0.783 0.756
Model selected (AIC) GTR+I+G GTR+I+G GTR+G GTR+G GTR+I+G GTR+I+G
a
The consistency index is calculated excluding uninformative characters.
Fig. 3.
Mitotic metaphase of Zhengyia shennongensis T. Deng, D.G. Zhang & H. Sun.
A,
Micrograph of metaphase chromosomes;
B,
kar yoty pe
of mitotic metaphase chromosomes.
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95Version of Record (identical to print version).
woody at base, ca. 2 cm in diam. Sterile leaf axils often with
13 woody bulbils, fawn, globose or ovoid, 3–6 mm in diam,
often wit h adventi tious roo ts. Upper stem s and pet iole s densely
covered with stinging hairs and white pubescent. Stipules
greenish, leaf-like, herbaceous, persistent, solitary in leaf
axils, united with stem at base; stipule cordate or triangular-
ovate, 3–4 cm, margin subentire or minutely sparsely crenate,
base auriculate-amplexicaulous, apex long caudate-acuminate,
shallowly 2-cleft, basal veins 3. Leaves alternate; leaf blade
broadly ovate, 13–27 × 10 –26 cm, base shallowly cordate to
Fig. 4.
Single most par simon ious tree (tree le ng th = 2302, CI = 0.597, RI = 0.756) fro m the analysis of the combin ed nrITS and pt DNA sequen ces.
Numbe rs above branches indic ate boots tr ap suppor t (BP); numb er s below branches are Ba yes ian poste rior probabi litie s (PP); a dash (–) indic ates
that a node did not receive >80% BP in the MP analysis.
A,
achene shape;
B,
stipule position and shape (arrows indicate stipules);
C,
presence of
bulbils (arrows indicate bulbils);
D,
leaf arrangement.
96
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96 Version of Record (identical to print version).
Fig. 5.
Images of living plants of Zhengyia shennongensis T. Deng, D.G. Zhang & H. Sun.
A,
Habitat;
B,
habit;
C,
population;
D,
inf lorescence;
E,
stipules;
F,
bulbils;
G,
root;
H,
inflorescence;
I,
staminate f lower;
J,
pedicel;
K,
fruit.
97
Deng & al. • The new genus Zhengyia (Urticaceae)
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97Version of Record (identical to print version).
Fig. 6.
Holotype of Zhengyia shennongensis T. Deng, D.G. Zhang & H. Sun, gen. & sp. nov., with details.
A,
Habit;
B,
pistillate f lower (arrow
indicates stigma);
C,
staminate f lower;
D,
achene. — Drawn by X.-S. Zhang.
98
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98 Version of Record (identical to print version).
Abrahamson, W.G. 1980. Demography and vegetative reproduction.
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cordate, margin dentate or lobed; lobes deltoid, denticulate,
slightly falcate; apex shortly acuminate; cystoliths minutely
punctiform; lateral basal veins reaching middle lobes, sec-
ondary veins 4– 6 on each side, reaching teeth or anastomos-
ing before margin, adaxial surface with sparse, stinging and
setulose hairs, abaxial surface densely setulose and sparsely
armed with stinging hairs on veins. Petiole 12–16 cm. In-
florescences unisexual, in axillary pairs; paniculate with
many long branches; male inf lorescences in proximal axils,
paniculate, erect, 15–25 cm; female inflorescence terminal
or in subterminal leaf axils, pendulous, 20–30 cm, peduncle
2–4 cm. Staminate flowers ca. 1.5 mm, shortly pedicellate or
subsessile; perianth lobes connate below middle, apex not cor-
niculate; stamens 4, filaments incurved, longer than perianth,
anthers peltate; pistillode terete, ca. 0.3 mm. Pistillate f low-
ers ca. 1.3 mm, subsessile; perianth lobes 4, connate at base,
strongly unequal, the 2 dorsal-ventral lobes larger, enclosing
the ovary, elliptic-ovate, setulose, as long as achene; lateral
lobes smaller, ovate-lanceolate, ca. 1/2 as long as dorsal lobe.
Ovary ca. 1.1 mm, shortly stipitate, asymmetrically ovoid;
stigma spirally winding, short clavate, ca. 0.4 mm. Achene yel-
lowish green, oblong-globose or subglobose, ca. 1.2–1.5 mm,
conspicuously oblique, with dense nipple-shaped protuber-
ances on surface, enclosed by persistent enlarged dorsal-ven-
tral perianth lobes; stipe ca. 0.1 mm.
Etymology. —
Zhengyia is named in honor of Prof.
Zhengyi Wu, a renowned Chinese botanist who has studied
Chinese plants for over 70 years. He deserves this homage in
recognition of his important contributions to the field of plant
taxonomy and floristics, to his deep involvement in training
new researchers and his tremendous contribution to our knowl-
edge of the flora of China.
Distribution and habitat. —
Despite extensive investiga-
tion s in ce ntr al Ch ina by the collect or s of th is ta xon, the species
has so far only been found in the area of Wushanhu Mountain
in the SNNR, in the southwest part of Hubei province, central
China (Fig. 1). The new species is probably calcicole. It prefers
shady and wet habitats with deep humus-rich soil. It grows in
small clusters in the valley and on limestone mountain slopes
mainly at 500 to 600 m. These ancient limestone mountains in
the region are deeply eroded and dissected by deep river val-
leys. The globose woody bulbils are probably associated with
a rain-splash dispersal mechanism: when bulbils are released
from parent plants, they are washed down the mountain slope
by rainwater and have the potential to spread more widely via
streams.
Conservation status. —
Endangered, based on the occur-
rence in an area smaller than 5000 kand known at fewer
than five localities (IUCN, 2001).
Phenology. —
The peak f lowering period was observed
in September and fruiting specimens were found in October
and November.
Paratype. —
China. Hubei province, Shennongjia Forest
Dist r ict (SNNR), Yan gri town , Wugu Mountai n, 110°5035″ E ,
31°3237″ N, 450 m alt, 4 Sep 2011, T. Deng, D.G. Zhang
& H. Sun 2593 (KUN).
ACKNOWLEDGMENTS
This study was supported by grants-in-aid from the National
Natural Science Foundation of China (Grant no. NSFC, 31061160184),
Hundred Talents Program of the Chinese Academy of Sciences
(2011312D1102 2), Stra te gic Pri or ity Res ear ch Progra m of the Ch ine se
Acad em y of Scien ce s (XD B03030106), NSF C-Yu nna n Na tur al Scienc e
Foundation Unite Project (Grant no. U1136601), and the Research Pro-
gram from the Ministry of Science and Technology of China (Grant no.
2007FY110100) to H. Su n and the research program for Postdoctoral
Scholar, Ke y Lab or at ory of Biod iver sity an d Bioge ogr ap hy, Kunm i ng
Instit ute of Botany, CAS (Grant no. Y0205111L1) to C. Kim. The
authors wish to thank X.K. Fan for SEM operation and for preparing
the photos. We are also grateful to L.-E. Yang and G.-F. Chen for as-
sistance with the chromosome counts, and to X.-S. Zhang for the line
drawings. Finally, we would like to thank the anonymous reviewers
for their valuable comments and suggestions.
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Appendix 1.
Voucher information and GenBank accession numbers for taxa used in this study. Information is presented i n the following order: Species
name, collection locality, abbreviation of OTU, collector and collection nu mber (herbarium acronym), Gen Bank accession number for nrITS, rbcL, psbA-
trnH, and trnL-F. (SNJ Exped. = Shennong jia Expedit ion).
INGROUP: Dendrocnide basirotunda (C.Y. Wu) Chew, Ch in a, Yun nan , dt 20 2, Deng 408 (K UN) , KC2 84962 , KC 28 498 8, KC28 50 40 , KC2 85014; Dendrocnide
urentissima (Gag ne p.) Chew, Ch in a, Yun nan , dt 20 3, Deng 40 9 ( KUN ), KC28 4963, KC2849 89, KC28 50 41, KC2 85 015; Girardinia diversifolia (Li nk) Frii s su bs p.
diversifolia, Chin a, Yun na n, dt115, Nie 4248 (KU N), KC284955, KC28 4981, KC285033, KC285007; Girardinia diversifolia subsp. suborbiculata (C.J. Ch en)
C.J. Chen & Friis, China, Hubei, dt094, SN J Exp ed . 20111107 004 (KU N), KC284950, KC284976, KC285028, KC285002; Girardinia diversifolia subsp. triloba
(C.J. Chen) C.J. Chen & Friis, China, Hubei, dt079, SNJ Exped. 20110906024 (KUN ), KC28 4945, KC28 49 71, KC28502 3, KC28 49 97; Hesperocnide tenella Tor r.,
U.S.A., California, sm336, B. Trusk 188 ( US) , KC2 84 967, KC2849 93 , KC2 85045 , KC2 85019; Laportea bulbifera (Siebold & Zu cc .) Wed d. , Ch ina , Hu be i, dt0 76,
SNJ Exped. 20110730020 (KUN ), KC284942, KC284968, KC285020, KC284994; China, Yunnan, dt109, Nie 3717 (KUN), KC284951, KC284977, KC285029,
KC28 500 3; Laportea cuspidata (Wedd.) Friis, China, Hubei, dt078, SNJ Exped. 20110714028 (KUN), KC284944, KC284970, KC285022, KC284996; China,
Hubei, dt083, SNJ Exped. 20110723090 (KUN), KC284946, KC284972, KC285024, KC284998; Laportea interrupta (L.) Chew, China, Yunnan, dt113, Nie
4263 (K U N) , KC2 84 954, KC 28 498 0, KC285032, KC2850 06; Poikilospermum suaveolens (Blume) Merr., China, Yunnan, dt205, De ng 411 (KU N), KC28496 4,
KC284990, KC285042, KC285016; Urtica dentata Hand.-Ma zz., Chi na, Hubei, dt230, SNJ Ex ped. 20110724077 (KUN), KC284966, KC284992, KC285044,
KC2 85 018; Urtica fissa E. Pr itz., China, Hubei, dt198, SN J E x ped . 201111120 01 (KUN), KC284960, KC284986, KC285038, KC285012; Urtica laetevirens
Maxim., China, Hunan, dt124, D.G. Zhang 134 (KU N), KC284956, KC2 84982, KC285034, KC2850 08; Urtica mairei H. Lév., Ch in a, Yunn an , dt110, Nie 4292
(KUN ), KC284952, KC284978, KC285030, KC285004; China , Sichuan, dt127, Liu & Yuan MY-121 (KUN ), KC284957, KC284983, KC285035, KC285009;
China , Hunan, dt199, Deng 406 (KU N) , KC28 4961, KC284987, KC285039, KC285013; Urtica thunbergiana Siebold & Zucc., China, Yunnan, dt112, Nie 4 275
(KUN ), KC284953, KC284979, KC285031, KC285005; Urtica triangularis Hand.-Mazz., China, Sichuan, dt133, Qingzhang Exped . 5801 (KUN), KC28 4958,
KC284984, KC285036, KC285010; China, Xizang, dt135, Qingzhang Exped. 12157 (KUN ), KC2849 59, KC28 498 5, KC285037, KC2 85011; Zhengyia shennon-
gensis T. Deng & al., Chi na , Hub ei, dt08 8, SNJ Ex ped . 20110904001 (KUN), KC2849 48, KC2849 74, KC285026, KC28500 0; Ch in a, Hu bei , dt0 91, SNJ Exped.
20111107 0 01 (KU N), KC28 4949, KC 28 4975, KC285 027, KC2850 01. OUTGROUP: Boehmeria spicata Thun b., Chin a, Hub ei , dt 07 7, SNJ Exped. 20110812020
(KU N), KC284943, KC2 84969, KC285021, KC 2849 95; Pilea plataniflora C.H. Wright, China, Hubei, dt228, SNJ Expe d. 20110714007 (KUN), KC284965,
KC284991, KC2850 43, KC285017; Fatoua villosa Nak ai, Chi na , Hube i, dt086 , SNJ Exped. 20110802047 (KUN), KC284947, KC284973, KC285025, KC284999.
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... Importantly, we clarify which of the Urticeae genera are strongly supported as monophyletic or polyphyletic (Figure 5). Compared to previous studies based on a limited number of genes (Hadiah et al., 2008;Deng et al., 2013;Wu et al., 2013Wu et al., , 2018Kim et al., 2015;Grosse-Veldmann et al., 2016;Huang et al., 2019;Wells et al., 2021), we exploited the utility of whole CP genomes for resolving phylogenetic relationships in Urticeae, and also revealed the most informative sites and regions across the plastome. Our results proved to be largely consistent with most of the recently established phylogenetic relationships of Urticeae based on a range of 3-7 selected marker regions (Wu et al., 2013(Wu et al., , 2018Kim et al., 2015;Huang et al., 2019;Wells et al., 2021). ...
... The most notable finding from our two-locus phylogenetic analysis was the reconstruction of Hesperocnide as polyphyletic, consistent with Huang et al. (2019). Our current CP genome + nrDNA analysis and prior molecular studies, however, recovered Hesperocnide as monophyletic (Kim et al., 2015), with a close relationship to Urtica (Sytsma et al., 2002;Hadiah et al., 2008;Deng et al., 2013;Wu et al., 2013;Kim et al., 2015). The polyphyletic results from the two-locus tree can be ascribed to the sampling of members of the second species that were absent in the plastome analysis. ...
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Urticeae s.l, a tribe of Urticaceae well-known for their stinging trichomes, consists of more than 10 genera and approximately 220 species. Relationships within this tribe remain poorly known due to the limited molecular and taxonomic sampling of previous studies, and chloroplast genome (CP genome/plastome) evolution is still largely unaddressed. To address these concerns, we used genome skimming data—CP genome and whole nuclear DNA (18S-ITS1-5.8S-ITS2-26S); 106 accessions—for the very first time to attempt resolving the recalcitrant relationships and to explore chloroplast structural evolution across the group. Furthermore, we assembled a taxon rich two-locus dataset of trnL-F spacer and nuclear ITS (nrITS) sequences across 291 accessions to complement our genome skimming dataset. We found that Urticeae plastomes exhibit the tetrad structure typical of angiosperms, with sizes ranging from 145 to 161 kb and encoding a set of 110 to 112 unique genes. The studied plastomes have also undergone several structural variations, including inverted repeat (IR) expansions and contractions, inversion of the trnN-GUU gene, losses of the rps19 gene, and the rpl2 intron, and the proliferation of multiple repeat types; 11 hypervariable regions were also identified. Our phylogenomic analyses largely resolved major relationships across tribe Urticeae, supporting the monophyly of the tribe and most of its genera except for Laportea, Urera, and Urtica, which were recovered as polyphyletic with strong support. Our analyses also resolved with strong support several previously contentious branches: (1) Girardinia as a sister to the Dendrocnide-Discocnide-Laportea-Nanocnide-Zhengyia-Urtica-Hesperocnide clade and (2) Poikilospermum as sister to the recently transcribed Urera sensu stricto. Analyses of the taxon-rich, two-locus dataset showed lower support but was largely congruent with results from the CP genome and whole nuclear DNA dataset. Collectively, our study highlights the power of genome skimming data to ameliorate phylogenetic resolution and provides new insights into phylogenetic relationships and chloroplast structural evolution in Urticeae.
... The Urticaceae that have aerial vegetative diaspores are two species of Laportea and the monotypic Zhengyia shennongensis, all of eastern Asia. The three species are not immediately related to one another, and even the two species of Laportea are in separate clades of a non-monophyletic genus (Deng et al., 2013). Nevertheless, they have in common the production of "woody bulbils" in the leaf axils (Chen et al., 2003;Deng et al., 2013;Bhellum and Singh, 2016), however, these authors are vague as to the definition of "woody bulbil." ...
... The three species are not immediately related to one another, and even the two species of Laportea are in separate clades of a non-monophyletic genus (Deng et al., 2013). Nevertheless, they have in common the production of "woody bulbils" in the leaf axils (Chen et al., 2003;Deng et al., 2013;Bhellum and Singh, 2016), however, these authors are vague as to the definition of "woody bulbil." A close-up photograph of L. bulbifera available online (https://commons.wikimedia.org/wiki/ ...
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Aerial vegetative diaspores — often simply called “bulbils” in the botanical and horticultural literature — are diverse in morphology, origin, position, and modes of dispersal. This review examines their occurrence in the Angiosperms, their morphology and site of origin, and possible ecological and evolutionary advantages. Moreover, a standard terminology is proposed based on three criteria: dormancy, polarity, and whether the storage tissue is leaf or stem. We review the taxonomic and geographic distribution of bulbils, cormlets, tubercles, and gemmae, their modes of dispersal, and whether dispersal mode differs from that of the seeds. We detect geographic biases in the distribution of plantlets and tubercles (mostly tropical in distribution) versus bulbils, cormlets, and gemmae (mostly temperate). We note the physiological differences between seeds and aerial vegetative diaspores, which may account for differences in modes of dispersal, which for aerial vegetative diaspores includes anemochory, epizoochory, endozoochory, barochory, and hydrochory. Additional research is suggested so that gaps in our understanding of this common form of asexual reproduction can be filled.
... All taxonomic information was gathered and released as the "Catalogue of life China 2013" in Species 2000 (http://www.sp2000.org.cn/). The higher plants in SCCP, are chiefly based on "Catalogue of life China 2013," while the FOC (Wu et al., 1989(Wu et al., -2013, FRPS (Flora Reipublicae Popularis Sinicae Editorial Committee, 1959-2004, newly published literature (e.g., Deng et al., 2013;Wang et al., 2014), and web resources like the International Plant Name Index (IPNI; https://www.ipni.org/) and Tropicos (https://www.tropicos. ...
... For example: Porolabium and Frigidorchis were transferred into Herminium (Raskotia et al., 2016), Ancylostemon, Bournea, Briggsia s.str., Dayaoshania, Deinocheilos, Isometrum, Opithandra, Oreocharis, Paraisometrum, Thamnocharis, and Tremacron were merged into Oreocharis . Moreover, some new genera were added, such as Zhengyia (Deng et al., 2013), Singchia (Liu & Chen, 2009), and Parasyncalathium (Zhang et al., 2011), and so forth. The SCCP has also documented new records of genera (including the naturalized genera), new combinations, and widely cultivated genera for China. ...
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The Species Catalogue of China: Volume 1: Plants (SCCP) is a new, comprehensive, hardcopy inventory of Chinese higher plants that combines several datasets and references to recent taxonomic treatments. The database, with all attached additional information, is freely accessible via the internet (http://www.sp2000.org.cn/) and on CD‐ROM, and will be updated yearly. It includes bryophytes (157 families, 599 genera, and 3,167 specific and infraspecific taxa), lycophytes and ferns (41 families, 181 genera, and 2,336 specific and infraspecific taxa), gymnosperms (10 families, 45 genera, and 311 specific and infraspecific taxa), and angiosperms (270 families, 3,227 genera, and 35,873 specific and infraspecific taxa); in total 478 families, 4,052 genera, and 41,687 specific and infraspecific taxa. Several other important statistics can also be drawn from the database, such as the distribution pattern of the four major groups of higher plants, as well as number of endemic and naturalized or cultivated genera/taxa. Entries in SCCP are also compared with Flora of China, and Flora Reipublicae Popularis Sinicae at the genus level. The SCCP will not only be a useful reference for floristic or biodiversity studies in China, but will also serve as a key resource to direct action and monitor progress. It is intended to be a useful resource for achieving Target 1 of the Global Strategy for Plant Conservation (GSPC). This article is protected by copyright. All rights reserved.
... The Flora of Shennongjia includes 27 species of lycophytes (in four genera of two families), 306 pteridophytes (in 71 of 25), 43 gymnosperms (in 27 of 7) and 3391 angiosperms (in 1117 of 174) ). Based on recent field studies and further research, several new species (Deng et al. 2016;Xie et al. 2017;Lin et al. 2019) and new genera (Deng et al. 2013) of flowering plants were proposed from SNNR. During one expedition, we found a population of a species of Trichosanthes of Sect. ...
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Trichosanthes sunhangii D.G.Zhang, Z.M.Li, Qun Liu & T.Deng, a new species of Cucurbitaceae, is described and illustrated. It was collected in Shennongjia Forestry District, Hubei province, east-central China. T. sunhangii is morphologically similar to T. kirilowii Maxim. and T. rosthornii Harms, but can be easily distinguished from them by its bracts, tendrils and fruits. Phylogenetic analyses based on three DNA barcode markers (ITS, matK and rpl20-rps12) indicated that two accessions of T. sunhangii were grouped together (PP=1.00, BP=100 and LP=100) in Sect. Foliobracteola.
... Quite often the fruit stipe has also moved to the same side (Fig. 14F). The character of straight or oblique achenes was used to delimit genera within the tribe Urticeae (Weddell 1856(Weddell -1857Friis 1993;Deng et al. 2013). It was later shown that in the Urticaceae and allied families the fruit are pseudomonomerous, two-carpellate, the sterile carpel being more or less suppressed (Bechtel 1921;Eckardt 1937;Berg 1989). ...
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Fruit morphology and the anatomical structure of the pericarp, fruiting perianth, and seed coat were studied in 15 species of Poikilospermum, a genus whose position within the Urticaceae has long been controversial. Possible evolutionary trends of their transformation are suggested for both subgenera; plesiomorphies were found in P. oblongifolium and P. scabrinervium. Structural peculiarities of the fruit connected with its ejection out of the tubular perianth are discussed. The archaism of the fruit in Poikilospermum is revealed, indicated, as in Boehmeria, by the presence of the rudiment of an aborted carpel in the form of a large two-lobed rib. Using carpological anatomical characters, the species studied are classified into informal groups, such characters being able to pull the species within the subgenera into rough groupings where gross morphology has been unable to do so. It is shown that heterobathmy may be strongly associated with the genus Poikilospermum. Each subgenus has its own set of primitive carpological characters: in subgenus Poikilospermum the absence of a fruiting perianth which encases the fruit, and also of capitate inflorescences with swollen receptacles; in subgenus Ligulistigma remnant rudiment of the second carpel and ovary loculus, as well as a primitive, less simplified seed coat. Though the position of Poikilospermum as indicated by molecular data is within Urera, our results suggest that Dendrocnide (the only genus of the Urticeae that has a pyrenarium fruit type) may be closest to Poikilospermum, although the pericarp structure and dissemination behaviour in Poikilospermum are more specialised than those exhibited by Dendrocnide. Seed coat structure is also shown to exhibit traits seen in Moraceae.
... Plants exhibit a high degree of plasticity in axillary forms including dormant axillary buds, tillers, vegetative branches, or other specific axillary structures (Li et al., 2003;Evers et al., 2011). In some circumstances, plants evolve unique aerial bulbils derived from the growth of meristems in the axils of leaves or bracts, in response to the ecological or evolutionary niches in which the plant grows (Law et al., 1983;Szarek et al., 1996;Ronsheim and Bever, 2000;Deng et al., 2013). In particular, the bulbils released from the mother plants can grow into new individuals in the next growth season, and offer a failsafe strategy of asexual reproduction when seeds are absent under harsh environmental conditions (Arizaga and Ezcurra, 2002;Walck et al., 2010). ...
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In yam (Dioscorea spp) species, bulbils at leaf axils are the most striking species-specific axillary structure and exhibit important ecological niches. Genetic regulation underlying bulbil growth remains largely unclear so far. We here first characterized yam (D.alata L.) bulbil development using histological analysis, and performed full transcriptional profiling on key developmental stages together with phytohormone analyses. Using the stage-specific scoring algorithm, we identified 3,451 stage-specifically expressed genes that exhibit a tight link between major transcriptional changes and stages. Coexpressed gene clusters revealed an obvious overrepresentation of genes associated with cell division, expansion at the initiation stage of bulbil (T1). Transcriptional changes of hormone-related genes highly coincided with hormone levels, indicating that bulbil initiation and growth are coordinately controlled by multi-phytohormones. Particularly, localized auxin is transiently required to trigger bulbil initiation, and be further depleted or exported from bulbils to promote growth by up-regulation of genes involved in auxin-conjugation and efflux. The sharp supplies of sucrose and enhanced trehalose-6-phophate pathway at T1 were observed, suggesting that sucrose likely functions as key signal and promotes bulbil initiation. Analysis of transcription factors (TFs) expression predicated 149 TFs as stage-specific expressed; several T1-specific TFs (from Aux/IAA, E2F, MYB, and bHLH families) have been shown to play key roles in triggering bulbil formation. Together, our work provides a crucial angle for in-depth understanding the molecular programs underlying yam's unique bulbil development processes. Stage-specific gene sets can be queried to obtain key candidates regulating bulbil growth, severing as valuable resources for further functional researches.
... The degree to which F. verna produces seeds, bulbils, and tubers is variable and may depend on which subspecies is present. Bulbils are thought to have evolved in response to limited pollinator visitations in moist habitats mainly caused by a shady living environment (Deng et al. 2013). It appears that bulbil germination rates by the end of the year are extremely high, indicating little innate dormancy in the field. ...
Article
Lesser celandine, Ranunculus ficaria L., an invasive plant from Europe, is becoming widespread in river valleys throughout the Northeastern United States and the Pacific Northwest. Its high rate of asexual bulbil and tuber production create dense infestations threatening native spring ephemerals. Ranunculus ficaria abundance and reproductive output (seeds, bulbils and tubers) were examined in invaded transects spanning a disturbance gradient away from a river. Site characteristics (PAR, soil pH, moisture, texture and nutrients) were quantified to examine their role in plant abundance and reproduction. A larger-scale study examined random transects not specifically chosen based on R. ficaria infestations. Soil characteristics and slope were hypothesized to drive R. ficaria abundance and reproduction; we also hypothesized that reproductive output and biomass would be highest at intermediate distances from rivers where disturbances are infrequent. R. ficaria abundance and reproductive output varied considerably by site; soil characteristics, rather than landscape placement, appeared to drive plant abundance and reproduction. Lower percent sand was associated with significantly higher R. ficaria stem density and bulbil and tuber production. Cation exchange capacity was significantly negatively related to R. ficaria biomass and tuber counts. In the larger-scale survey, slope and PAR were significantly negatively related to R. ficaria presence and percent cover, respectively. Overall, these findings suggest that soil texture and slope can help explain higher abundance and reproductive outputs. However, reproductive output and biomass were not significantly greater at intermediate distances, contrary to expectations. We did not observe any seed production in any of the plots, although we did see a few plants with seeds outside our study area in the second year, demonstrating a near complete reliance on asexual reproduction in these populations. This study expands on the current limited understanding of R. ficaria , which can help management by identifying areas likely to support dense infestations.
Article
Abstract Premise Paleontologists use tooth form to assess diets of fossil mammals. Plants would also be expected to adapt their morphology to respond to herbivory. Fossil nettle leaves with definitive stinging trichomes (tribe Urticeae, family Urticaceae) are described from the early Eocene upland lacustrine floras of the Okanogan Highlands, British Columbia, Canada. This is the first report of stinging trichomes in the fossil record. Their occurrence in western North America at a time of major large herbivorous mammal radiation suggests they acted, as they do today, as a deterrent for mammal herbivory. Methods Fossil leaf compressions and extant leaves were photographed with standard methods. Focus‐shift stacking was used to layer photos of the fossil leaves. Results Urticaceous fossil leaves from the Okanogan Highlands greatly resemble their modern relatives in leaf morphology and particularly in both stinging and nonstinging trichomes. Nettles are common components of the flora of the Volcanoes National Park in Rwanda. This region is used as a modern analogue for the Okanogan Highlands, based on comparable elevation, equable conditions that host both similar floras and large folivores. Conclusions Nettles in tribe Urticeae (Urticaceae) producing leaves with stinging and nonstinging trichomes were already present in the early Eocene of western North America at a pivotal time during the early radiation of modern mammalian herbivore groups. They offer tantalizing evidence of a selective response that plants may have developed to protect themselves from the evolving mammalian herbivores of that time.
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Geum sunhangii – first discovered in Shennongjia National Nature Reserve, Hubei Province, China – is described as a new species of Rosaceae. Compared to all known Chinese Geum species, the new species differs by possessing jointed styles, imbricate petals and a reniform radical leaf terminal leaflet. Most significantly, the jointed style is curved at an obtuse or a right angle. In addition, the inclusion of this species within the genus Geum was supported by phylogenetic analysis using the sequence data of a nuclear ribosomal internal transcribed spacer (nrITS) and a chloroplast trnL–trnF intergenic spacer. The new species was found to be closely related to G. rivale and G. aleppicum .
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Nanocnide zhejiangensis X.F. Jin & Y.F. Lu, a new species of Urticaceae from Zhejiang, East China, is described with illustrations. The new species is morphologically similar to Nanocnide japonica in having staminate inflorescence longer than leaves, but differs by having glabrous stems, petioles, peduncles and abaxial leaf surfaces, glabrous perianth lobes of staminate flowers, dorsally glabrous perianth lobes of pistillate flowers, and acuminate or solitary spinose‐setaceous at the apex. Cluster analysis based on the sequences of the ITS, atpF–H, atpB–rbcL and trnL–F also demonstrate that Nanocnide japonica is the closest extant relative to the new species. This article is protected by copyright. All rights reserved.
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This volume - the first of this series dealing with angiosperms - comprises the treatments of 73 families, representing three major blocks of the dicotyledons: magnoliids, centrosperms, and hamamelids. These blocks are generally recognized as subclasses in modern textbooks and works of reference. We consider them a convenient means for structuring the hundreds of di­ cotyledon families, but are far from taking them at face value for biological, let alone mono­ phyletic entities. Angiosperm taxa above the rank of family are little consolidated, as is easily seen when comparing various modern classifications. Genera and families, in contrast, are comparatively stable units -and they are important in practical terms. The genus is the taxon most frequently recognized as a distinct entity even by the layman, and generic names provide the key to all in­ formation available about plants. The family is, as a rule, homogeneous enough to conve­ niently summarize biological information, yet comprehensive enough to avoid excessive re­ dundance. The emphasis in this series is, therefore, primarily on families and genera.
Article
The recently-developed statistical method known as the "bootstrap" can be used to place confidence intervals on phylogenies. It involves resampling points from one's own data, with replacement, to create a series of bootstrap samples of the same size as the original data. Each of these is analyzed, and the variation among the resulting estimates taken to indicate the size of the error involved in making estimates from the original data. In the case of phylogenies, it is argued that the proper method of resampling is to keep all of the original species while sampling characters with replacement, under the assumption that the characters have been independently drawn by the systematist and have evolved independently. Majority-rule consensus trees can be used to construct a phylogeny showing all of the inferred monophyletic groups that occurred in a majority of the bootstrap samples. If a group shows up 95% of the time or more, the evidence for it is taken to be statistically significant. Existing computer programs can be used to analyze different bootstrap samples by using weights on the characters, the weight of a character being how many times it was drawn in bootstrap sampling. When all characters are perfectly compatible, as envisioned by Hennig, bootstrap sampling becomes unnecessary; the bootstrap method would show significant evidence for a group if it is defined by three or more characters.
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Rapateaceae (16 genera, ˜100 species) is largely restricted to the tepuis and sandplains of the Guayana Shield in northern South America, with Maschalocephalus endemic to West Africa. The family has undergone extensive radiation in flower form, leaf shape, habit, and habitat. To analyze the evolution of these distributions and traits, we derived a molecular phylogeny for representatives of 14 genera, based on sequence variation in the chloroplast-encoded ndhF gene. The lowland subfamily Rapateoideae is paraphyletic and includes the largely montane subfamily Saxo-fridericioideae as a monophyletic subset. Overall, the morphological/anatomical data differ significantly from ndhF sequences in phylogenetic structure, but show a high degree of concordance with the molecular tree in three of four tribes. Branch lengths are consistent with the operation of a molecular clock. Maschalocephalus diverges only slightly from other Monotremae: it is the product of relatively recent, long-distance dispersal, not continental drift—only its habitat atop rifted, nutrient-poor sandstones is vicariant. The family appears to have originated approximately 65 Mya in inundated lowlands of the Guayana Shield, followed by: (1) wide geographic spread of lowland taxa along riverine corridors; (2) colonization of Amazonian white-sand savannas in the western Shield; (3) invasion of tepui habitats with frequent speciation, evolution of narrow endemism, and origin of hummingbird pollination in the western Shield; and (4) reinvasion of lowland white-sand savannas. The apparent timing of speciation in the Stegolepis alliance about 6–12 Mya occurred long after the tepuis began to be dissected from each other as the Atlantic rifted approximately 90 Mya. Given the narrow distributions of most montane taxa, this suggests that infrequent long-distance dispersal combined with vicariance accounts for speciation atop tepuis in the Stegolepis alliance.
Article
A complete understanding of the systematics of perennial Urtica in North America has been lacking. Chromosome counts from plants from 77 locations revealed a base number of x = 13 with diploid and tetraploid levels. Artificial hybridization showed that diploid and tetraploid chromosome races were interfertile within their particular chromosome level. Scanning electron microscope observations of pollen grains revealed that different chromosome races are distinguishable by exine sculpturing. Biosystematic evidence supports the grouping of the perennial taxa into three subspecies of U. dioica.
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— We studied sequence variation in 16S rDNA in 204 individuals from 37 populations of the land snail Candidula unifasciata (Poiret 1801) across the core species range in France, Switzerland, and Germany. Phylogeographic, nested clade, and coalescence analyses were used to elucidate the species evolutionary history. The study revealed the presence of two major evolutionary lineages that evolved in separate refuges in southeast France as result of previous fragmentation during the Pleistocene. Applying a recent extension of the nested clade analysis (Templeton 2001), we inferred that range expansions along river valleys in independent corridors to the north led eventually to a secondary contact zone of the major clades around the Geneva Basin. There is evidence supporting the idea that the formation of the secondary contact zone and the colonization of Germany might be postglacial events. The phylogeographic history inferred for C. unifasciata differs from general biogeographic patterns of postglacial colonization previously identified for other taxa, and it might represent a common model for species with restricted dispersal.