Bull. Natn. Sci. Mus. , Tokyo, Ser. B, 28(3), pp. 93- 98, September 22, 2002

A New Species of Heterostemma lobulatum inthe Family Asclepiadaceae
Yan Hui Li 1, Fumihiro Konta 2 and Junko Kitagawa 3
1Kunming Botanical Institute, Chinese Academy of Science,Heilongtan, Kunming, Yunnan, China
2
Department of Botany, National Science Museum,Amakubo, Tsukuba 4- 1- 1, Tsukuba, 305- 0005 Japan
3International Research Center for Japanese Studies,
Oeyama Goryo 3-2, Nishikyoku, Kyoto, 6 10- 1192 Japan

Abstract Taxonomic description and notes of Heterostemma lobulatum Y. H. Li et F. Konta are
given in this paper. This species was discovered by the authors in Xishuangbanna, Yunnan, China
during the course in 1988 expedition and reported as nomen nudum in 1996. The species is characterized by yellow flowers with two lateral lobules on each corona lobe. Floral characteristics suggest a derived taxonomic position of genus Heterostemma including Heterostemma lobulatum in
the Asclepiadaceae .
Key words: Asclepiadaceae, taxonomic description, Heterostemma lobulatum , Ynnan.

Heterostemrna lobulaturn Y. H. Li et F. Konta
was discovered by the authors of this paper at
Hoiwa in Xishuangbanna, Yunnan, China in
1988. The name of this new species was recordedon the list of plants in Xishuangbanna (Y. H. Li ,1996) without taxonomical description. The present paper aims to describe the species and togive some taxonomical notes of this speies. Floral characteristics of this species seems to show aderived taxonomic position of genus Hetrosternrna including Heterosternrna lobulaturn in thefamily Asclepiadaceae. This study is a part of theserial taxonomical works of Asclepiadaceae in
China and Thailand (Konta & Kitagawa, 1989;
Konta, T. P. Li & Kikkawa, 1989; Konta, 1991).
The genus Heterosternrna has about 30 species
distributed in tropical and subtropical Asia. FromChina, 11 species have hitherto been reported (T.
P. Li , 1977) and seven from Xishuangbanna (Y.
H. Li , 1996) including Heterosternrna lobulaturn .

Materials and methods
Materials were collected at Hoiwa m
Xishuangbanna and fixed by the mixted fixiative

solution of alcohol 3 and gracial acetic acid I.
They were preserved in 70% ethanol solution
after the fixiation. Preparations for light microscopic observation were prepared usuing theusual paraffin embedding methods. Serial sections of 8 pm in thickness were stained with Delafield's Haematoxylin and Eosin, or Delafield'sHaematoxylin, Saffranin and Methyl-green. Materials for scanning electron microscopic observation were dehydrated in an ethanol series, critically point-dried, and coated with gold.
Taxonomical description of Heterostemma
lobulatum Y. H. Li et F. Konta
Heterostemma lobu/atum Y. H. Li et F. Konta sp. nov.

Affine Heterostemrnati siamico, sed corona
trilobulata lobulis lateralibus valide minoribus
differt.
Liana. Stems pubescent, green up to I 0 m inheight. Leaves opposite, stipe 1- 3.5 mm long,lamina elliptic to oblong, 4- 12 cm long, 1.5- 5 cmwide, apex acute, base cuneate, glabrous (Fig. I) .
Pedicel 15- 25 mm long. Flowers blooming in autumn , perfect, pentamerous except for the gynoe-

94

Yan Hui Li , Fumihiro Konta , and Junko Kitagawa

11 ER B. NO 29oau

Fig. I.

Holotype of 1-/eterostemma lobulatum Y. H. Li. et F. Konta.

ctum; calyx lobes triangular, 5 mm long, I mmwide, valvate, shortly connate at base, corollawith short tube, saucer-shaped or disk-shaped,
9- 10 mm in diameter, yellow (Fig. 2); corolla

lobes, valvate, spreading, triangular, 3- 3.5 mm
long, 3.5 mm wide, apex acute, glabrous: filaments inserted on the corolla tube, anther wings
connate leaving five vertical lacunae into a sheathTaxonomical notes on Heterostemma lobulatum

Fig. 2.

95

Habit of Heterostemma lobulatum at the type locality.

around the style and adherent to the stigma head,forming gynostegium (Fig. 3-1, 2); corona stamineal , crown-shaped with five lobes, each lobe
connate at base and centrifugally elongating at
the upper part forming lanceolate lobe with two
short lateral lobules, without vascular strand(Fig. 3-3 ; Fig. 4-1, 2, 4); anther with two globule
pollinia, two pollinia of adjacent anthers combined with plate-shaped translator and a corpusculum forming yellow twin pollinia; gynoeciumof two carpels forming separate, unilocularovaries with distinct styles and united only by thecommon style-head, which is star-shaped intransverse and sagittate in vertical section, narrow furrow at the top, and lateral surfaces haveglandular tissue of one cell in thick (Fig. 3-1, 3;Fig. 4-2, 4); ovaries superior; ovules unitegmic,
anatropous with short funicles on submarginalplacenta, number of ovules were two in transverse and four in vertical section of young ovary(Fig. 3-1 , 4). Fruit of two distinct follicles.
Habitat. Among dense evergreen thickets ormixed ones of evergreen and deciduous trees onlimestone hills.
Holotype. Meng Xing Ho Hoiwa, Mung La
County, Xishuangbanna, Yunnan, China. Coli.
Yan Hui Li , Fumihiro Konta, and Junko Kita-

gawa no. 40, Oct. 11 , 1988 (KUN)).
Taxonomical notes of Heterostemma lobulatum
Y. H. Li et F. Konta

Heterostemma lobulatum is similar to Heterostemma siamicum in habitat and floral characteristics; both grow in dense evergreen thickets ormixed ones of evergreen and deciduous trees onlimestone hills and bear sauser or disk-shaped
yellow flowers. However, Heterostemma lobulatum differs from Heterostemma siamicum incorona and leaf shape. Heterostemma lobulatumis characterized by the corona with a lanceolate
lobe with small two lateral lobules and ovate toelliptic leaves with angustate at base. Heterostemma siamicum has corona lobule without
lateral lobules and ovate leaves with truncate atbase.
The floral characteristics of Heterostemma
lobulatum are noted in detail in this paper as astudy of the serial taxonomical works of Asclepiacdaceae in China and Thailand noted above.
The procecess of development of the corona wasalso observed. Cells near the abaxial surface ofeach stamen were stained densely with Haematoxylin and Eosin at the stage of very young

96

Yan Hui Li , Fumihiro Konta, and Junko Kitagawa

Fig. 3. Vertical and transverse sections of flowers of Heterostemma /obu/atum. I. Vertical section of gynostegium showing two ovaries connate to a stigma head and vertically arranged ovules in each ovary. 2. Verticalsection of anther showing glandular tissue at the lateral wall of stigma head. 3. Transverse section of flower
showing two ovaries, basal part of five stamineal corona lobes, and a tube of corolla. 4. Transverse section offlower showing two submarginal ovules in each ovary (I, 3. XSS, 2, 4. X I 00).

Taxonomical notes on Heterostemma lobulatum

97

Fig. 4. Top view and vert ical sect io ns of flowers of Heterostemma lobulatum. I. Top view of gynostegi um
showing corona with a lanceo late lobe and latera l sma ll lobu les whi ch characterize Heterostemma lobulatum.
2. Vertica l section of flower showing coro ll a and base of co rona lobe. 3. Top view of gynostegium show ing
five anthers and a furrow of sti gma head. 4. Vertica l section of flower show ing filament with si ngle vascul ar
strand and stamineal corona lobe witho ut vasc ular supp ly (I. X20, 2. X20 , 3. X 50, 4. X20).

buds. Thi s part deve loped rapidly at the laterstages near the opene of corolla lobes to form
lobulate corona. Similar processes are observed
w ith the other Asclepiad species studi ed ( Konta& Kitagawa , 1989; Konta, T. P. Li & Kikkawa,1989; Kitagawa & Konta, 1990; Konta, 1991 ).
Fig. 3-1 and 3-4 show that sma ll er numbers ofovules in a ovary of Heterostemma lobulatum
than other Asclepiad species such as Cvnanchum

auriculatum (Konta, Suda, & Kobayashi , 1966)
and Telosma cordata (Konta, T P. Li , & Kikkawa,1989). Floral characteristics of Heterostemma
lobulatum including small numbers of ovules in aovary (Fig . 3-1 , 4), and the development of corona lobes without vascular strands (Fig. 4-2 , 4)during later stages of flower development seems
to suggest that the genus Heterostemma has derived in taxo nomical position in the Asclepi-98

Yan Hui Li, Fumihiro Konta, and Junko Kitagawa

adaceae. However, plate-shaped translator suggest primitive character. Further floral morphplogical studies of many other species in Heterostemma should be done to evaluate the taxonomical position of the genus Heterostemma including Heterostemma lobulatum.

Acknowledgements
The authors are greatly indebted to Professor
Sheng Ji Pei and Mrs. Guo Wen Fu of Kuming
Botanical Institute, Chinese Academy of Sciences for their kind advice and help during thecourse of this study.

References
Konta, F., T. Suda, & Ch. Kobsayashi, 1986. A prelimi-nary study on the fl oral morphology of Cynanchum(Asclepiadaceae), Acta Phytotax.Geobot. 37: 59-68.
Konta, F., & J. Kitagawa, 1989. Taxonomic notes of Asclepiadaceae in Thailand I, The floral morphology ofDischidia raffresiana Wall., Marsdenia glabra Cost.,
and Secamoneferruginea Pierre et Cost, Acta Phytotax.
Geobot. 40: 125- 132.
Konta, F. , T. P Li, & K. Kikkawa , 1989. A note on the floral morphology of Telosma cordata (Burm. f.) Merr.
(Asclepiadaceae), Acta Phytotax. Geobot. 40: 68- 74.
Konta, F., 1991. Taxonomical notes of Asclepiadaceae inThailand Il, Streptpcaulon Wight et Arn., Acta Phytotax. Geobot. 42 : 85- 91.
Li, P T., 1977. Flora Reipublicae Popuralis Sinicae, 63 :
512- 521 , Science Press, Beijing.
Li, Y. H. (ed.), 1996. Lists of plants in Xishuangbanna
389, Yunnan Minolities Press, Kunming.