Faithful Bee but orchid "Pre-ejaculates"
Dear Jack:Here's a recently published paper that takes an odd twist to the story of the flower "waiting" for the faithful bee. The orchid self-pollinates in the bud stage (not too unusual) but then it opens its flowers and is visited by Apis cerana. The bee is useless as a pollinator as the orchid has already pollinated itself. Once the pollinium is on the stigma it can't be re-affixed to the bee.The situation is probably not unique to this orchid species. Dr. Meier and I have been continuing my older interest in Thelymitra in Australia. It's a vernal-flowering genus. Small-flowered species in this genus often self-pollinate in the mature bud but then open rather pretty petals on hot spring days. Nevertheless, recurrent hybrids have been recorded between several self-pollinating species and between self-pollinating and cross-pollinated (large-flowered) species. Observations by earlier naturalists noted visitation by syrphid flies that consume stigmatic fluids and l"nibble" the crumbling pollinia on the stigma. Hybrids then are supposed to occur when a fly visits an open self-pollinated flower transfrring a few grains to the "virgin stigma" of a second species with open flowers. We found that syrphids certainly do carry Thelymitra pollen on their mouth parts although we never found a fly carrying the whole pollinarium (viscidium, caudicles and pollinia pairs) of a large-flowered or small-flowered species to date.Peter-