226 ON THE ASCLEPIADEiE.
Obs. Asclepias cordata, Forsk. Arab. p. 49, and Cy- nanchum extensum, Jacq. ic. 1, t. 54, are the only certain species of the genus : from the latter, Asclepias scandens, Palis. Flor. D'Oware, I, p. 92, t. 56, is probably not dis- tinct, and Cynanchum bicolor, And. Hepos. 562, is very nearly related to it.
��SARCOSTEMMA.
Char. Corolla rotata.
Corona staminea duplex ; exterior cyathiformis v. annu- laris, crenata ; interior 5phylla, exteriorem superans, foliolis carnosis.
Anther a membrana terminate. si] Masses pollinis apice affixse, pendulse.
Stigma subrauticum.
Folliculi graciles, lseves. Setnina comosa.
Habitus. Caulis volubilis v. decumbens, aphyllus, arti- culatus, v. foliis oppositis distantibus. Flores umbellati, laterales v. terminales.
Patria. India Orientalis, Nova Hollandia, et Africa.
Obs. To this genus belong Cynanchum viminale, Linn. ; a species nearly allied to it from New Holland and New- Caledonia ; and Asclepias viminalis, Linn., all of which I have examined. The probable species are, Asclepias aphylla, Thunb. prod. ; Asclepias stipitacea, Forsk. Arab. 50 ; Cynanchum pyrotechnicum, and perhaps also Ascle- pias aphylla, of the same author.
EUSTEGIA.
Char. Corolla rotata.
Corona triplex ; singula 5phylla ; extima fauce inserta laciniis limbi opposita ; reliqua extima alternantia, antheris opposita, foliolis medics tripartitis, intimes indivisis.
Antheræ membrana terminate.
Masses pollinis apice attenuato aflixae, pendulse.
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