Períploca Græ̀ca, L., a woody climbing plant of the Old World, in ornamental cultivation, and in one or two places inclined to be spontaneous, represents a tribe with granulose pollen loosely aggregated in two masses in each anther-cell. It has a brownish rotate corolla, very hairy within, and with 5 awned scales in the throat.
Tribe I. CYNANCHEÆ. Anthers tipped with an inflexed or sometimes erect scarious membrane, the cells lower than the top of the stigma; pollinia suspended.
[*] Stems erect or merely decumbent.
1. Asclepiodora. Corolla rotate, merely spreading. Crown of 5 hooded fleshy bodies, with a salient crest in each. Leaves alternate.
2. Asclepias. Corolla reflexed, deeply 5-parted. Crown as in n. 1, but with an incurved horn rising from the cavity of each hood. Leaves usually opposite.
3. Acerates. Corolla reflexed or merely spreading. Crown as in n. 1, but with neither crest nor horn inside. Leaves mainly alternate.
[*][*] Stems twining. Leaves mostly opposite.
4. Enslenia. Corolla erect. Crown of 5 membranaceous flat bodies, terminated by a 2-cleft tail or awn.
5. Vincetoxicum. Corolla rotate, spreading. Crown a fleshy 5–10-lobed ring or disk.
Tribe II. GONOLOBEÆ. Anthers with short if any scarious tip, borne on the margin of or close under the disk of the stigma; pollinia horizontal.