A very strange legume

This plant had us really baffled. The leaves had the fine, feather-like venation of a Tephrosia, but they were simple (not compound), sessile, and strangest of all, the flowers were sessile in the leaf axils (Tephrosia generally has multi-flowered, stalked inflorescences). After a bit of detective work (aka browsing the field guides back at camp!) we learnt that this plant is a Ptycholobium meaning "folded pod" - see last photo.