Of those flowers receiving a pollinium in the present study, 92% (Hemlock Ravine) and 91% (Long Lake) also had at least one removed.
Instead, it is possible that a larger labellum does not constrain a pollinator to brush against a pollinium or stigma with sufficient force to ensure pollen transfer.
(3) If the stimulus quality is high, and the stimulus threshold of an attracted wasp is low, pollinium removal will proceed (although more often the male will leave the flower after a short pause).
(1) The pollinia hypothesis suggests that a switch from reward to deceit was possible given that the single transfer of a pollinium may yield high levels of fruit set.
The Marsdenieae are mainly separated from the Geropegieae by the absence of a hyaline insertion crest on the upper or outer edge of the pollinium (if present, it lies on the inner or lower edge of the pollinium), and the more or less complete absence of an outer corona (Bruyns & Forster, 1991; Omlor, 1998).
Kunze (1995) has shown that only this insertion crest becomes lodged in the guide rail and that growth of the pollen tubes takes place through the concave face of the pollinium. We have verified this in Gonolobus gonocarpus, but it needs to be tested more widely across the tribe.
The many pollinaria illustrated by Kupicha (1984) demonstrate clearly how variable the position of attachment of the caudicle to the pollinium may be in the Asclepiadeae: from the apex to near the middle of the outer edge.
(1996) of the pellucid margin (hyaline insertion crest) on the pollinium is particularly worrisome.
First, unless foreign pollen donors are homozygous for one or more alleles not present in the target population, it is likely that some percentage of the hundreds of pollen genotypes carried in each immigrant pollinium
will be cryptic (i.e., identical to some of those produced by plants within the target population).