Lianas or scandent shrubs. Leaves with petioles swollen at the base and usually at apex, leaving a prominent cup-like scar on the stem; Inflorescences axillary or ramiflorous, mostly cymose, the peduncles sometimes 1-flowered and fascicled.
Asia-Tropical: Australasia:, Queensland (Queensland ‒ present) S. China: present SE. Asia: present
S. China and SE. Asia throughout Malesia to Queensland; 9 spp.
The genus Pycnarrhena has proved very difficult to revise owing to the inadequacy of the material available. Of the nine species recognized, the fruits of one are unknown, while the flowers (of both sexes) and inflorescences are unknown for another. In addition, female flowers are unknown for four species. Since fruits and inflorescences provide the most useful characters for separating species of this genus, the lack of some of this essential information is a major disadvantage in framing a taxonomic revision. Moreover, there is considerable variation between specimens in their foliage, and without other correlated characters, it has been most puzzling in certain instances to decide exactly where to draw the boundary between species. For these reasons I have been unable to frame a practical key which will work in general for single specimens, i.e. male or female, but the information incorporated in it will limit considerably the different possibilities when naming.
DIELS - in Pfl. R. 1910: 48
MIERS - in Ann. Mag. Nat. Hist. 1867: 11
MIERS - in Contr. Bot. 1871: t. 142
HOOK.F. & TH. - in Contr. Bot. 1871: 351
HOOK.F. & TH. - in Kew Bull. 1979: 568
MIERS - in Ann. Mag. Nat. Hist. 1867: 12
HOOK.F. & TH. - in Kew Bull. 1975: 97, 99
FORMAN - in Kew Bull. 1972: 405