Reproductive Assurance Through Autogamy in Some Annual Weed Species

Abstract

Weeds have evolved numerous adaptations to establish, survive and spread rapidly in disturbed habitats. Although prolific seed production is recognized as an important adaptation, studies on their pollination ecology, which is the basis of seed production, have remained neglected. One of the adaptations expected in weed species is autogamy which enables them to set seeds even in uncertain pollination environments. This is particularly important for annual weeds as they have only one chance to set seeds in their life and if they miss this chance, population survival is at risk. Pollination ecology and seed set were studied in eight common annual weed species—Achyranthes aspera, Crotalaria pallida, Malvastrum coromondelianum, Melochia corchorifolia, Solanum nigrum, Stachytarpheta indica, Tridax procumbens and Triumfetta rhomboidea. The extent of autogamous self-pollination and seed set were studied in bagged flowers and compared with those which have access to floral visitors. Autogamy was prevalent in all the species leading to high seed set. There was no significant difference in the extent of pollination and seed set between bagged and open-pollinated flowers in any of the species. Floral visitors were recorded only in three of the species. Reproductive assurance through autogamy is an important adaptation in annual weeds which contributes to their success.