Monday 9 January 2012

Still not a tamarind


The plants keep fruiting.

31 December 2011


When I looked through the rainforest fruits book and found the illustration of the northern tamarind (Diploglottis diphyllostegia, Sapindaceae) (not actually a tamarind) I was sure I’d got my ID.



But it wasn’t quite right. The fruit matched the picture, but the leaves did not. Diploglottis diphyllostegia has compound leaves with 14 to 22 pairs of veins. The leaves on this plant are simple with rather fewer veins



I eventually found it — Dichapetalum papuanum (Dichapetalaceae) — a shrubby vine of FNQ and New Guinea. Dichapetalaceae is a pantropical family of 124 species in four genera. Dichapetalum is the only genus of the family in Australia. Two species occur in Far North Queensland. (See map below.)



Some species of Dichapetalum are known to produce the metabolic poison sodium fluoroacteate to deter herbivores. At least one (D. gelenoides of the Philippines) is a nickel hyperaccumulator. It looks as though these plants have declared all-out war on their predators. (I'll go out periodically to inspect the levels of herbivory to see who's winning. I'm predicting a stalemate.)



Herbarium records for the two Australian species of Dichapetalum: D. timorense (green) and D. papuanum (red). Both species also occur in New Guinea and Malesia.

Specimen data reproduced from Australia's Virtual Herbarium
with permission of the Council of Heads of Australasian Herbaria Inc.