A note upon the way in which bees settle on flowers of Derris thyrsi-flora and the injury resulting from their search for honey
This note by I. H. Burkill documents the mechanical injury inflicted on Derris thrysiflora flowers by visiting bees and the consequences for seed-set.
Summary
Burkill describes how bees force apart the interlocked petals of Derris thrysiflora in their search for honey, causing consistent and characteristic damage. The claws of the petals, which function as springs, are ruptured and suffused with black pigment from the broken epidermal layer. Two dark spots invariably develop at the base of the standard, near the brow over the path to the honey, often composed of three or four confluent perforations. Corresponding perforations appear on the wings, particularly at points where the wings and keel are interlocked, where visitors gain the best purchase (p. 264).
The keel, which protects the pollen, is rarely marked except at its claws and tip. Burkill notes that while every flower is repeatedly visited, over 90% fall entire without setting seed; the remainder, though a small percentage, produce what he considers an abundant seed-crop (p. 264).