Fig. 2.

A female Halictus xanthopus Kirby (Halictidae) briefly basking before departure on the border of the corona of a very herkogamous, relatively long-styled flower of Narcissus longispathus which it has just visited for pollen collection. The body of the pollen-laden bee is contacting the stigma. This occasional pollinator (approx. 11 mm long) is slightly larger than Andrena bicolor (9 mm), the main pollinator of N. longispathus. It is suggested that flowers with large anther–stigma separations experience low outcrossing rates because of the increased probability of self-pollination derived from a greater proximity of the stigma to the border of the corona, where pollinators frequently stop to thermoregulate before flying (Herrera, 1995).