Abstract

HOC, Patricia S.  and  AMELA GARCIA, María T.. Biología floral y sistema reproductivo dePhaseolus vulgaris var. aborigineus (Fabaceae). Rev. biol. trop [online]. 1999, vol.47, n.1-2, pp.59-67. ISSN 0034-7744.

Observations made in Salta, northern Argentina, for a complete flowering season of five plants from several patches, allowed the authors to conclude: 1. anthesis lasts 9-13 hours and consists of two floral phases, in the last of which the stigma is not receptive; 2. stigma is receptive in the bud when anthers are not dehiscent, hence the flowers are protogynous; 3. nectar is secreted during phase 1 only; 4. the nectar composition fits that of melittophylous plants; 5. rain or drizzle do not affect the nectar composition or pollen viability because they are highly protected but do affect visitation by pollinators; 6. flowers are flag-blossom pollination units with pollen presented on stylar subapical trichomes, adapted to medium-sized hymenopterans, which transfer the pollen on their heads; 7. the ISI and RRS reproductive indeses show that the variety is partially self-compatible, but insect visitation increases reproductive success; 8. individuals of Centris sp. and a breed of Bombus atratus are the most important legitimate visitors because they work on all conspecific plants and suck nectar in few flowers ( phase 1) per plant during each visit, while individuals of Bombus opifex, the other breed of B.atratus and Megachile spp. are also legitimate pollinators but less frequent or not constant; 9. some Lepidoptera are nectar robbers because they suck nectar but do not trigger the pollen transfer mechanism.

Keywords : Phaseolus; Fabaceae; floral biology; reproductive system; Argentina.