Two New Subspecies of Desmodium laxum (Leguminosae) from China

5 Pages·1995·0.44 MB·English

by  Hiroyoshi Ohashi

植物研究雑誌
1. Jpn. Bot
70: 144-148 (1995)
TwoN ewS ubspecies of Desmodium laxum (Leguminosae) from China
Hiroyoshi OHASHI
Biological Institute，Fa culty of Science，To hoku University，Se ndai，98 0 JAPAN
(Received on November 17，1 994)
Two new subspecies of Desmodium laxum DC. are described from China. These subspecies agree with
D. laxum subsp. laxum in the pods and venation pattem of the leaflets，bu t are entirely different from the typical
subspecies in shape and nature ofthe leaves. One ofthe new subspecies，su bsp.falfolium H. Ohashi，ha s leaves
similar to D. podocarpum DC. subsp.fall似 (Schindler)H. Ohashi，an d the other，su bsp. lateraxum H. Ohashi，
has smaller leaflets similar to D. laxum subsp. laterαle (Schindler) H. Ohashi or D. podocarpum var.
szechuenense. Except these intermediate mo叩hologicalfeatures no evidence for hybrids is found in these
subspecies.
During my studies on Desmodium of China，1 1987) and their habitats are similar to each other.
found two unknown plants in the herbarium of the Seeds are usually not developed in hybrids. Pruits of
Kunming Botanical InstItute (KUN) in Yunnan. These these plants are too young，a nd cannot be judged
plants have deeply constricted and long-stipitate pods， whether the seeds are fertile or infertile，be cause they
hence，th ey belong clearly to the section Podocarpium are not yet developed in the pod. At present，th erefore，
in the subgenus Podocarpium. They are similar to D. these plants are not judged as hybrids.
laxum especially in the inflorescences，po ds and vena- Though 1c ould examine only one sheet for each
tion pattem of the leaflets，b ut，s how remarkable plant and could not confirm the nature of leaves as
differences in the leaves. Both have seemingly de- well as other characters of both plants on other
ciduous leaves against the evergreen leaves of D. specimens，at present，h owever，1 t hink that it must be
laxum and entirel yd iffer in shape of their leaves from worthwhile for giving an ame and description to
the known range of variation of leaves of D. laxum. each of them for references of future researches，a nd
The shape and nature of their leaves are similar to that they are better to be recognized at the rank of
other species in the section Podocarpium or other subspecies in D. laxum.
subspecies of D. laxum. Key to these new subspecies distinguishing from
These plants，a ccordingly，m ay possibly be re- D. laxum subsp. laxum is as follows:
garded to be hybrids，if any supporting evidence could 1. Leaves evergreen，u sually sparse on stem or ap-
be found. Occurrence of hybrids between different proximate on lower parts; terminalleaflets elliptic
species of the section Podocarpium may be possible， or ovate，6- 8.5 cml ong，3. 5-5 cm wide ....
because the chromosome numbers ofthese taxa so far ..subsp. laxum
known are all 2n=22 (Ohashi and Iijima 1980，C ui 1. Leaves probably deciduous ・... ・.....・ ・.....・ ・..….2
H H H
-144一一
ー
June 1995 Joumal of Japanese Botany Vol. 70 No. 3 145
2. Leaves approximate at the top of stem; terrninal 1. Desmodium laxum DC. subsp. falfolium H. Ohashi
leaflets broadly e11iptic or broadly ovate，4- 5 cm (Fig. 1).
long，2. 7-3.2 cmw ide .…..，・ ・..subsp.fiαlfolium This plant is characteristic in having ae xtremely
H
2. Leaves approximate on upper part of stem; ter- short stem，ap proximate leaves at the top of stem，an d
minal leaflets narrowly elliptic，a bout 4.5 cm broadly elliptic or broadly ovate leaflets with uni-
long，1. 5c mw ide ....・ ・..，・ ・...subsp.lαteraxum forrnly pubescent above. Such ah abit and the shape of
H H
leaflets are similar to those of D. podocaJpum DC.
Fig.l. Holotype of Desmodium laxum subsp.falfolium H. Ohashi.
146 植物研究雑誌第70巻第3号 平成7年6月
subsp.fallax (Schindler) H. Ohashi. In leafy charac- Liu 9858 (holotypus in KUN).
ters，h owever，it s venation pattem agrees that of D. A perennial herb，w ith ligneous slightly tubular
laxum，.i e.，th e lateral nerves looped within the mar- roots. A stem about 5c mh igh，wi th closely approxi-
gin. Based on these features as well as other character- mate 4l eaves at the apex，d ensely retrorse short-
istics on pods this new plant appears to be intermedi- pubescent. Leaves 3-foliolate，se emingly deciduous;
ate between Desmodium podocarpum subsp. fallax stipules deciduous，l anceolate，a bout 2m ml ong，
and D. laxum subsp. laxum. pubescent on margin of the upper parts; petioles 2.5-
Desmodium laxum DC. subsp. falfolium H. Ohashi， 4 cm long，d ensely pubescent. Terminal leaflets
subsp. nov. stipellate，br oadly ovate or broadly elliptic，4 -5 cm
A typo caule brevissimo，fo liis approximatis ad long，2. 7-3.5 cm wide，pu bescent above，u niformly
apicem，et foliolis late ellipticis vellate ovatis differt. pubescent beneath，pr inciple lateral nerves 3p airs and
Typus: West Hunan. Baojin County: Shipong. In not reaching the margin directly; lateralleaflets ses-
mountain forest，an erect herb with reddish pods.しH. sile，sm aller than the terminal one. Ani nf10rescence
Fig. 2. a. The holotype of Desmodium laxum subsp. lateraxum H. Ohashi; b. The infIorescence of holotype.
June 1995 Joumal of Japanese Botany Vol. 70 No. 3 147
terminal，ab out 15 cm long，wi th scattering minute probably deciduous，a pproximate on upper p訂tof
hooked hairs. Pedicels about 1.2-1.5 cm long，w ith stem. Stipules lanceolate，st riate 4-5 mml ong，0 .7
minute hooked hairs. Androecia monadelphous. Pods mmw ide，al most glabrous. Petioles 2.5-3 cm long，
with 3-4 articles，th e stipe 1.2-1.4 cml ong，gl abrous. almost glabrous. Terminalleaflets narrowly elliptic，
acute at both ends，a bout 4.5 cml ong，1. 5 cmw ide，
2. Desmodium laxum DC. subsp. lateraxum H. appressed pubescent on main nerves on both surfaces，
Ohashi (Fig. 2). lateral nerves looped within the margin; lateralleaf-
When 1f ound as pecimen of this plant in KUN，1 lets smaller than the terminal one，ob lique at base，3 -
thought it as. ah ybrid between Desmodium laxum 3.5 cm long，1 -1.3c m wide. Inflorescences pseudo-
subsp.laxum andD. laxum subsp.lαterale (Schindler) racemose，a bout 17 cm long，g labrous，w ith 2-3
H. Ohashi or between the former and D. podocarpum flowers at an ode; bracts early deciduous; pedicels
var. szechuenense Craib，b ut，1 c ould not find more 5-6 mml ong，m inutely pubescent. Calyx about 1.5
definite characters suggesting hybrid nature of this mml ong，4- 10bed，th e upper lobe rounded，th e lateral
plant. Several young pods of the plant without mature obtuse at apex，t he lower broad triangular，0 .5 mm
seeds are not an evidence for the hybrid origin. 1 long，s parsely minute hooked hairy. Wings about 6
tentatively accommodate this plant as as ubspecies of mml ong; keel-petals about 5.5 mml ong. Androecia
D. laxum. This new subspecies is characteristic in about 5m ml ong. Pods (when young) (2-)3-jointed，
having small leaflets similar to those of D. 1αxum densely covered with hooked hairs on the lateral
subsp.laterale or，ex cept for the venation pattern，D. surfaces; stipes 12-18 mml ong，gl abrous.
podocarpum var. szechuenense，bu t the flowers and
fruits are almost entirely identical with those of D. 1w ould like to thank Professor Su-Kung Wua nd
laxum subsp. laxum. Dr. Hang Sun of Kunming Botanical Institute for
Desmodium laxum DC. subsp.lateraxum H. Ohashi， their kind help for mys tudies in their herbarium. This
subsp. nov. study was financially supported by grant-in-aid No.
A typo foliolis minoribus probabiliter deciduis 04041019 (1992-94) to H. Ohashi from the Monbu-
differt. Foliola terminalia anguste elliptica，ac uta，ca . sho International Scientific Research Program.
4.5 cm longa，1. 5 cm lata.
References
Typus. China. Guizhou. 8F eb. 1959. Expedition
Cui X. J. 1987. Karyotype analysis of 3s pecies of genus
team to Anxun no. 710 (holotypus in KUN). Podoca中iumand chromosome numbers of 2s pecies of
genus Desmodium. Bu1 .1Bo .tResearch 7(3): 123-130.
Ap erennial herb with aw oody root stock，ab out 35
Ohashi H. and Iijima，M . 1980. The chromosome of the section
cm high. Leaves 3-foliolate with persistent stipules， Podocarpium (Leguminosae-Desmodium). J. Jap. Bot. 55(8):
238-243.
大橋広好:オオバヌスビトハギの中国産2新亜種
オオノてヌスビトハギ Desmodiumlaxum DC. ていたところ，全体的な形は非常に異なっている
subsp. laxumは日本，中国，東南アジア， インド が，花序と果実の特徴からみてオオパヌスビトハ
に分布する. 日本では千葉県以西に比較的多く生 ギのー形であると思われる標本を2種類，それぞ
育するが，中国では広く分布しているが個体数は れ1枚ず、つ見つけた. これらは今まで知られてい
多くないようである.当然生育すると思われる台 ない形のものであった. 1枚は湖南省で採集され，
湾ではまだ記録されていない. 1994年8月に，昆 ケヤブハギの特徴を持つ葉をつけたもので，他の
明植物研究所所蔵のヌスビトハギ属の標本を調べ 1枚は貴州省で発見されたリュウキュウヌスビト
148 植物研究雑誌第70巻第3号 平成7年6月
ハギあるいは中国固有のヌスビトハギの変種 きていない.それぞれ1枚ずつの標本しか無かっ
Desmodium podoca中umvar. szechuenenseの葉に たため，分類群としての特徴を十分には調べられ
似た葉をつけるものであった.両方の新植物とも なかったが，形態的特徴が明らかであり，果実の
オオパヌスビトハギとそれらの種類との聞の雑種 形態と小葉の脈理がオオバヌスビトハギに一致す
である可能性が考えられるが，形態上の類似性以 るので， これらの標本の個体は両方とも D.
外の特徴は確認できなかった.図1と2のように， laxum DC.の亜種として認めておくこととした.
いずれも若い果実をつけているが，種子はまだで