XVI International Botanical Congess

The purpose of this study was to compare flowering and dispersal events, flower size (FS), nectar traits [sugar composition (SC), volume (V), concentration (C), and mg of sugar/flower (MG)], and flower visitors (FV) between species of Asclepiadaceae (ASC, n=6) and Apocynaceae (APO, n=4) of a Chaco Serrano community from central Argentina. Most species have extended flowering and fruiting periods. ASC matured fruits faster than APO. Statistically significant differences were found for all traits between both the families and also the plant life forms. APO species showed larger FS with a larger amount of concentrated sucrose rich nectar per flower than did ASC. Perennial herbs had larger FS with a lower amount of dilute, sucrose rich nectar than did vines. Of the assemblage of flower visitors recorded, most species were considered to be generalist. Results indicate that phylogenetic and/or life form constraints have a higher evolutionary influence on flower traits of these species than do their pollinators.