Family Apocynaceae > Subfamily Apocynoideae > Tribe Apocyneae.
There are 9 species native to China, Asia, India and Indonesia.

They are vigorous mostly evergreen woody vines (lianas).
Stems can be up to 20 m long.
Damaged parts exude a milky latex and hairs may or may not be present.

The opposite leaves are on a petiole that usually has glands.
The large ovate, obovate or oblong leaves may be smooth or variously hairy.

Terminal or axillary inflorescences are cymes – branched with the terminal flower on each branch opening first.
There are large leafy bracteoles at the base of the pedicels (flower stalks).
The calyx has 5 large free sepals with glands at the base inside.
The long or short corolla tube has 5 short white overlapping lobes that curve back.
The tube has a short narrow lower section then a long widening funnel-shaped section.

The 5 stamens are inserted at the top of the narrow section of the corolla tube.
The filaments are free but the anthers are stuck to the stigma.
The arrow-shaped anthers have long pointed basal lobes.

The annular nectary disc inside the stamens has 5 irregular lobes.
The superior ovary of 2 carpels has 2 locules with numerous ovules.
There are hairs on the ovary and base of the style.
It is difficult to separate the anthers from the long green stigma without damaging it.

The fruit are hard woody paired follicles each with numerous seeds.
Follicles may have some hairs.
Seeds have a tuft of silky hairs at one end.