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Morphology and Polymorphism in the Pollen of Christia
and Uraria (Leguminosae: Papilionoideae)
Bin YEa*a nd Hiroyoshi OHASHlb
，
'Biological Institute，Gr aduate School of Science，T ohoku University，Se ndai，9 80-8578 JAPAN;
*Present address: Graduate School of Life Sciences，T ohoku University，Ka tahira，Se ndai，9 80・8577JAPAN;
bBotanical Garden，Gr aduate School of Science，T ohoku University，K awauchi，Se ndai，9 800862JAPAN
・
(Received on December 28，2 001)
Pollen grains of four species in Christia and eight species in Uraria in the tribe
Desmodieae of subfamily Papilionoideae in Leguminosae were observed by scanning
electron microscopy (SEM) and transmission electron microscopy (TEM). Pollen mor-
phology of the two genera is characterized by ad iscontinuous or absent foot-layer and the
infratectum consisting of columellae and granules. Polymo中hicexine sculptures were
shown in two species of Christia，i.e .，C. constricta and C. vespertilionis，a nd three spe-
cies of Uraria，i. e.，U. lagopodioides，U. lagopus and U. rufescens. The variation occurs
among stamens within as ingle flower. Christia constricta shows the widest range of the
polymo叩hism.The similarity and variability in pollen grains provide clear evidence that
these two genera e'very close to each other.
訂
Key words: Christia，L eguminosae，p ollen morphology，p ollen polymorphism，U raria.
The genus Christia includes about ten spe- Chen and Huang (1993) described that these
cies which are distributed in tropical and two genera showed the same exine stratifica-
subtropical Asia and Australasia. The genus tion pattern but differ in tectum architecture.
Uraria contains about twenty species and is Microsporogenesis and exine substructure in
found in the Old World tropics (Ohashi et al. Uraria were studied by Liu and Huang
1981). These two genera are considered to (1999).
have close affinities in having specialized Chen and Huang (1993) reported that
fruits with folded articles. Ohashi (1971) ex- Uraria lagopodioides had dimorphic pollen
amined the pollen mo叩hologyof three spe- sculpture patterns. Variation in pollen mor-
cies of Christia and six species of Urariαby phology has been known within one species
light microscopy. He reported that these two and even within as ingle f10wer (Harris 1956，
genera were very similar to each other in Van Campo 1966，1 976). Dimorphic pollen
pollen sculpture. Mitra and Mondal (1982)， mo中hologyhas also been reported from
who also used light microscopy，re ported re- within individual flowers of Cassia (El
sults consistent with Ohashi (1971) that Ghazali 1993) and Lagerstroemia (Kim et al.
Christia and Uraria have the same pollen 1994) co'espondingto the heteromorphic
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type. In examining one species of Christia stamens.
and two species of Uraria from Taiwan by This study aims firstly to describe pollen
scanning electron microscopy (SEM) and morphology of Christia and Uraria，p ticu-
ぽ
transmission electron microscopy (TEM)， larly the pollen sculpture and exine structure，
-150-ー
June 2002 Journal of Japanese Botany Vo .l77 No. 3 151
based on observation by SEM and TEM; dard method (Erdtman 1960) and dehydrated
secondly to reveal the variation between in an ethanol series. The samples were air
these two genera by examining more species dried and coated with gold palladium，a nd
than previously studied; thirdly to investigate examined with aH itachi S-4100 scanning
whether the heteromorphic pollen grains electron microscope in the Biological
found in U. lagopodioides occur also in other Institute，T ohoku University. The polar and
species in the genus as well as in Christia equatorial lengths were measured on 30
and if so，to find at what level (i.e.，in divid- grains in each sample. For TEMo bservation，
ual，i nflorescence，f lower or stamen) the acetolysed pollen grains were fixed with 2%
polymorphic pollen grains occur. osmium tetroxide，e mbedded in Spurr low
viscosity resin. After sectioning with the
Materials and Methods glass knife，t he sections were stained with
Pollen materials were obtained from her- uranyl acetate and lead citrate，a nd examined
barium specimens kept in the Biological with Hitachi H- 8100 transmission electron
Institute，T ohoku University，S endai，J apan microscope in the Biological Institute，
(TUS); Arnold Arboretum in Harvard Tohoku University. Pollen terminology gen-
University Herbaria，C ambridge，U SA (A); erally follows Punt et al. (1994).
and' National Herbarium Nederland，
University Leiden branch， Leiden， The Results
Netherlands (L). A list of specimens used in Pollen morphology of Christia
this study is given in Table 1. Features of pollen grains common to all
In Christiα vespertilionis， Uraria four species of Christia examined eas fol-
紅
lagopodioides，U . lagopus and U. rufescens， lows: Pollen grains are tricolporate，m edium
pollen .sa mples were collected from one in size，s pheroidal to subprolate in shape，el -
flower per specimen. Six flowers of Christia liptic or rhombic in equatorial view，s emi
回
constricta were examined and whole of the angular in pol view.Colpi are medium，
紅
ten anthers from each flower were treated about 0.6-0.8 times the length of the pol
訂
separately. The position of each anther was axis，0 .1-0.3 times the width of the equato-
recorded. For SEM observation， pollen rial diameter，t apering to ap oint or some-
grains were acetolysed following the stan- times narrowing slightly to rounded ends;
Table 1. Sample list examined in this study
Taxa Voucher specimen Locality
Christia campanulata Y. Tateishi et al. 25187 (TUS) Kaoshiung，T aiwan
C. constricta Y. Tateishi et al. 1020026 (TUS) Hainan，C hina
C. obcordata T. C. Huang & S. F. Huang 12972 (TUS) Kaoshiung，T aiwan
C. vespertilionis Gen Murata et al. 43072 (TUS) Loei，T hailand
Uraria lacei T. Nemoto et a .l1006107 (TUS) Guangxi，C hina
U. cordifolia R. Geesink et al. 5847 (L) Chieng mai，T hailand
U. crinita Y. Ando et al. 415 (TUS) Nantou Hsiew，T aiwan
U. hispida Forrest 8851 (A) Yunnan，C hina
U. lagopodioides Y. Tateishi et al. 1019115 (TUS) Hainan，C hina
U. lagopus M. Togashi & H. Idzumi (TUS) Kodari，N epal
U. picta T. Miyagi (TUS) Ryukyu，Ja p an
ιrufescens T. Nemoto et al. 1019015 (TUS) Hainan，C hina
152 植物研究雑誌第77巻第3号 平成14年6月
colpus membrane is finely granulate; colpus rial diameter; P.厄=(0.99-)1.18(-1.23); scu-
margin is often undifferentiated from lpture of mesocolpium is granulate; infratec-
mesocolpium; endoapertures esmall to tum is defined; foot-layer is absen .t
訂
medium，0 .1-0.3 times the length of polar 4. Christia vespertilionis (L.f.) Bakh.f.
axis. Exine sculptures always showed (Fig. 1: F-K)
microperforations (holes 0.05-0.1μm in di- Pollen grains e(31.3-)33.0(-35.8)μmin
紅
ameter as Ferguson and Strachan，1 982) on pol axis，(26.0-)30.0(-34.4)μm in equato-
紅
the surface，u niform or polymorphic within rial diameter; P厄=(1.02-)1.10(-1.31); scu-
species，v ariable within one flower when lpture of mesocolpium is variable within one
polymorphic，m ost frequently microrugulate flower: microrugulate or granulate; infratec-
(consisting of elongated tectum less than 1 tum is indistinct; footlayeris discontinuous.
園
μm long) and granulate. Exine is 1-1.5μm
thick at mesocolpium，r arely ca. 2μm thick Pollen morphology of Urlαria
in Christia constrictα; tectum almost con- Features of pollen grains common to all
tinuous in section. Infratectum (= interstiti- eight species examined are as follows: Pollen
um，t he layer of the exine situated between grains are tricolporate，m edium or large in
the nexine and the tectum) consists of size. Spheroidal，s ubprolate to prolate in
columellae and granules (= reduced columel- shape，e lliptical or rectangul-ellipticalin
紅
lae); foot-layer discontinuous or absent; equatorial view，an gular，se mi-angular or cir-
tectum，in fratectum and endexine are almost cular in polar view. Colpi are medium to
equal in thickness，e ach about 113 of the long，ab out 0.7-0.9 times the length of polar
eXlne. axis，0 .1-0.3 times the width of the equato
帽
Features specific to each species examined rial diameter，t apering to pointed，o r some-
are as follows: times narrowing slightly to rounded ends;
1. Christia campαnulaω(Wall .) Thoth. colpus membrane is almost smooth or finely
(Fig. 1: A-B) granulate，oc casionally rugulate; colpus m
ぽ-
Pollen grains are (26.3一)30.8(-34.5)阿nin gin is often undifferentiated from mesocol-
pol axis，(24.0一)28.6(-32.5)μmin equato- pium. Endoapertures are small to medium，
訂
rial diameter; PA= (0.91-)1.08(-1.24); scu- 0.1-0.3 times the length of the polar axis.
lpture of mesocolpium is microrugulate; Exine sculptures always show microperfora-
foot-layer is discontinuous. tions on the surface: psilate，m icrorugulate
2. Christia constricta (Schindl.) T.C.Chen and/or granulate，u niform or polymorphic
(Fig. 4: I-J，Fi g. 5) within species，v ariable within one flower
Pollen grains訂e(28.8一)35.5(ー41.3)阿nin when polymorphic. Exine is 1-1.5μm thick
polar axis，(2 5.8一)33.1(-37.5)阿nin equato- at mesocolpium; tectum almost continuous
rial diameter; P.厄= (0.91-)1.08(-1.25); in section. Infratectum consists of columellae
exine is 1.5-2阿nthick in mesocolpium; and granules. Foot-layer is absent or reduced
tectum almost continuous in section，or dis- to discontinuous，ra rely nearly continuous in
continuous in section; foot-layer is discon- U. lagopus and U. rufescens. Tectum，in fra-
tinuous. The sculpture is extremely variable tectum and endexine are almost equal in
within one flower: psilate，m icrorugulate， thickness，ea ch about 1/3 of the exine.
granulate or veucate. Features specific to each species examined
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3. Christia obcordatα，(Poir.) B紘h.f.(Fig. are:
1: C-E) 1. Uraria lacei Craib (Fig. 2: A-B)
Pollen grains e(24.8-)27.4(-29.4)μmin Pollen grains are (29.2-)32.7(-36.9)μmin
紅
polar axis，( 23.9一)25.5(-27.5)μmin equato- polar axis，(2 7.7-)30.1(-31.7)凹nin equato-
June 2002 Journa1 of Japanese Botany Vol. 77 No. 3 153
Fig. 1. Pollen morphology of Christia campanulata (A-B)，C. obcordata (C-E) and C. vespeげilionis(F-K). A，
G: Polar view. Bar =5μ ffi. B，D ，J: Cross section at mesocolpium. Bar =1 11m. C，F ，1: Equatorial view of
mesocolpium showing microrugulate (F) and granulate (C，1) ，F a nd 1f rom as ingle flower. Bar = 51 1m. E，
=
H，K : Equatorial view showing aperture. Bar 5μm.
154 植物研究雑誌第77巻第3号 平成14年6月
Fig. 2. Pollen morphology of Uraria lacei (A-B)，U. crinita (C-E) and U. lagopodioides (F一K).A，G : Polar
ぃ
view. Bar = 5ドm.B，E ，J: Cross section at mesocolpium. Bar = 1 m.C，F ，1: Equatorial view of
mesocolpium with microperforations; psilate (F) and microrugulate (1) in as ingle flower. Bar = 5μm.D:
High magnification of surface of psilate showing very fine microperforations (holes ca. 0.05ドmin diame-
ter). Bar =1 μm. H，K : Equatorial view showing aperture. Bar =5 ドm.
June 2002 Journal of Japanese Botany Vol. 77 No. 3 155
rial diameter; P厄=(0.94-)1.09(-1.19); scu- continuous but almost continuous.
lpture of mesocolpium is psilate; infratectum 7. Uraria picta (Jacq.) Desv. ex DC. (Fig.
is well defined; foot-layer is discontinuous. 3: H-J)
2. Uraria cordifolia Wall. (Fig. 3: A-B) Pollen grains are (33.1-)34.6(-39.1)μmin
Pollen grains are (29.7-)40.2(-44.4) 11m in pol axis，(28.1-)30.9(-33.1)μm in equato-
訂
polar axis，(2 4.1)29.3(-34.4)μmin equato- rial diameter; P厄=(1.00-)1.13(-1.32)，sc u-
ー
rial diameter; P厄=(1.16-)1.38(-1.63); scu- lpture of mesocolpium is psilate; footlayer
四
lpture of mesocolpium is microrugulate; is discontinuous.
infratectum is well defined; foot -layer is dis- 8. Urariαrufescens (DC.) Schindl. (Fig. 4:
contmuous. A-H)
3. Uraria crinita (L.) Desv. ex DC. (Fig. Pollen grains are (26.7-)33.1(-42.7) 11m in
2: C-E) pol訂 axis，(24.0-)29.5(-34.7)阿nin equato-
Pollen grains are (39.3-)41.0(-43.5)μmin rial diameter; P厄=(0.93一)1.12(-1.32);scu-
polar axis，( 31.3-)34.3(-38.0)阿nin equato- lpture of mesocolpium is variable within one
rial diameter; P厄=(1.06-)1.20(-1.32); scu- flower: microrugulate or granulate; infra-
lpture of mesocolpium is psilate，w ith very tectum is well defined，c onsisting of vague
small microperforations (the hole 0.05μm in columellae; foot-layer is almost continuous.
diameter) (Fig. 2D ); infratectum is well de
同
fined; foot-layer is discontinuous. Pollen features common to Christiαand
4. Uraria hispidlα(Franch.) Schindl. (Fig. Uraria
3: C-E) Common features of pollen grains be-
Pollen grains are (23.3-)26.0(-28.1)仰nin tween Christia and Uraria are as follows:
polar axis，( 19.0一)22.0(-26.3)μmin equato- Tricolporate， spheroidal or sometimes
rial diameter; P厄=(1.07一)1.18(-1.32);scu- subprolate，r arely prolate，2 6.0-41.0μ.m in
lpture of mesocolpium is granulate; infra- average polar axis，2 2.0-34.3阿nin average
tectum is well defined; footlayeris absent. equatorial diameter. Sculpture always with
田
Taxonomic note: Recently，th is species is microperforations on the surface，u niform or
regarded as am ember of Desmodium based polymorphic in one flower within species.
on external morphological characteristics Exine usually 1-1.5μm thick at
(Ohashi et al. 2002). mesocolpium. Infratectum consists of
5. Uraria lagopodioides (L.) Desv. ex DC. columellae and granules. Foot-layer discon-
(Fig. 2: F-K ) tinuous or absent. Tectum，c olumella and
Pollen grains are (28.8-)33.4(-37.5) 11m in endexine ealmost equal in thickness，e ach
紅
polar axis，( 22.8-)30.1(-35.0)阿nin equato- about 1/3o f the exine.
rial diameter; P厄=(1.00-)1.11(-1.34); scu- Only af ew exceptional examples were
lpture of mesocolpium is variable within a seen as follows: Christia constricta some-
flower: psilate，m icrorugulate or granulate; times has thick exine (1.5-2μm). Uraria
infratectum well defined; foot -layer is dis- r.u作scenslacks granules in the infratectum.
cont1nuous. The foot-layer is basically discontinuous but
6. Urariαlagopus DC. (Fig. 3: F-G) entirely lacking in Christia obcordata and
Pollen grains e(26.4-)28.2(-30.1)μmin Urariαhispida，w hile almost continuous in
紅
pol紅 axis，(23.2-)25.5(-28.3)ドmin equato- U. lagopus and U. rゆscens.
rial diameter; p，厄=(1.00-)1.09(-1.34); scu-
lpture of mesocolpium is variable within a Intraspecific polymorphism of pollen
flower: psilate，m icrorugulate or granulate; sculptures in Christia and Urlαria
infratectum is well defined; foot-layer is dis- Pollen sculptures e polymorphic in
紅
156 植物研究雑誌第77巻第3号 平成14年6月
Fig. 3. Pollen morphology of Uraria cordifoliα(A-B)，U . hispida (C-E)，U. lagopus (F-G) and ιpicω(H-
J). A: Polar view. Bar = 5μm. B，D ，G ，1: Cross section at mesocolpium. Bar = 1μm. C，H: Equatorial view
showing mesocolpium. Bar = 5μffi. E，F ，J: Equatorial view showing aperture，a nd F: psilate and
microrugulate showing difference sculpture in one flower. Bar = 5f.l m.
June 2002 Journal of Japanese Botany Vol. 77 No. 3 157
Fig. 4. Pollen morphology of Uraria rufescens (A-H) and Christia constricta (I-J). A，D : Mesocolpium，eq ua-
torial view showing microrugulate (A) and granulate (D) in as ingle f1ower. Bar = 5ドm.B，E : Equatorial
view showing aperture. Bar =5 μm. C，F: Polar view. Bar =5 μm. G: Section of whole grain. Bar =5 μm.
H，1， J: Cross section at mesocolpium. Bar = 1ドm.
158 植物研究雑誌第77巻第3号 平成14年6月
Christia constrictα(Fig. 4: l-J，F ig. 5)，C . variable in the six f10wers examined;
，
vespertilionis (Fig. 1: F一K)，Uraria lagopo- microrugulate was the most common，g ranu-
dioides (Fig. 2: F一K)，U. lagopus (Fig. 3: F late and psilate ecommon，w hile veucate
訂 町
-G) and U. rujセscens(Fig. 4: A-H). Such was the rarest. Distribution of pollen types
polymorphic sculptures were found to occur between anthers was variable and no uniform
in as ingle f10wer in these species. The varia- pattems of variation among different f10wers
tion ranges of the sculpture are，h owever， was apparent (Fig. 7). The sculpture type
different among them. The widest range was was not associated with position of the sta-
found in Christia constricta which showed mens，th at is，n o pollen types were found in
psilate (Fig. 5: A1-C1)，mi crorugulate (Fig. 5: ac onstant position across the six flowers ex-
A2-C 2)，g ranulate (Fig. 5: A3 -C3)，a nd amined. Each pair of antesepalous stamens，
veucate(Fig. 5: A-C sculpture. Differen- i.e.，1 v s. 2a nd 3v s. 4，or antepetalous sta-
町 4 4)
ce among these sculpture pattems coe- mens，i. e.，2' and 3'，a nd 4' and 5'，h ad the
町
sponds to degree of uneveness of the tectum same pollen sculpture in f10wers 1，2 ，a nd 3，
from almost continuous and thin (Fig. 4: 1) to while it had almost the same pattem in
discontinuous and thick (Fig. 4: J). f10wer 4，b ut different in f10wers 5 and 6
Pollen grain variation in as ingle f10wer of (Fig. 7). The pollen sculptures in the adaxial
Christia constricta was examined in six stamen (1 ') were， for example， micro-
f10wers from one individual (voucher speci- rugulate in three f10wers (f1owers 3，5 ，a nd 6)
men: Tateishi et al. 1020026，T US) in order and psilate (f1ower 4)，g ranulate (f1ower 1)
to clarify whether ad efined pollen type oc- and veucate(f1ower 2) in one flower each.
町
curs in as pecific anther or not. And，if so， ln the case of stamen 5，w hich is opposite to
what pollen types are specific to what an- the adaxial one，fi ve f10wers (f1owers 1，2 ，3 ，
thers. Wea rbitrarily distinguished each sta- 4a nd 6) had the same pollen sculpture as the
men in one f10wer as shown in Figs. 6a nd 7 adaxial one but one (f1owers 5) is different as
and，al so，th e six f10wers are arbitrarily num- shown in Fig. 7.
bered“f10wer 1ぺ“f10wer2" and so on (Fig.
7) for convenience of description of the pol- Discussion
len variation. Stamens are diadelphous in all The results of our palynological study on
species of Christiαand Urariα: one free sta- Christia and Urariαby SEM and TEM
men，o n the adaxial side，is an antepetalous showed a c10se similarity in their pollen
stamen in the inner whorl (1' in Figs. 6a nd grains. The granular infratectum and the re
聞
7). The remaining nine stamens are found in duced footlayer were characteristic of
回
an antesepalous position in the outer whorl Christia and Uraria in the tribe Desmodieae
(1-5 in Figs. 6a nd 7) or antepetalous posi- (Ferguson and Skvarla 1979，C hen and
tion in the inner whorl (2'-5' in Figs. 6a nd Huang 1993)，a nd were considered to be de-
7). These ten stamens have homomorphic rived characters in the subfamily
anthers. Papilionoideae (Ferguson and Skvarla 1983).
The pol1en sculptures in the six examined The present study confirms that the
f10wers of Christia constricta are not uni- infratectum of Christia and Uraria examined
form but each anther has ad efinite sculpture consists of columellae and granules. Uraria
type. We recognized four types: psilate， lagopus and U. rufescens have，h owever，al -
microrugulate，gr anulate，a nd veucate(Fig. most continuous but discontinuous foot
町
国
7). All f10wers examined have two，th ree or layers.
four sculpture types in as ingle f1ower. The The common variability of pollen grains
pattem of occuenceof these types was between Christia and Uraria was c1arified.
町
June 2002 Journal of Japanese Botany Vol. 77 No. 3 159
Fig. 5. Polymorphic pollen grains from as ingle flower of Christia constricta showing psilate (A!，B !，C : type
1in Fig. 7)，mi crorugulate (A2，B2 ，C 2:t ype II in Fig. 7)，gr anulate (A3，B3 ，C 3:t ype III in Fig. 7) and verrucate
(A4，B4 ，C : type IV in Fig. 7). A!-A4:Eq uatorial view showing mesocolpium，B! ーB4:Equatorial view show-
ing aperture. C-C4:P olar view. Bar = 51 1m. Voucher specimen: Taiwan. Tateishi et al. 1020026 (TUS).
