Resource limitation of fruit and seed production in some Asclepias species

Abstract

Effects of modifying resource availability were studied on three species of milkweed, Asclepias syriaca, A. verticillata, and A. incarnata. The influence of mineral fertilizer, leaf removal, and shading were investigated to test the hypothesis that milkweed species are resource limited. Addition of mineral fertilizer resulted in increased numbers of mature pods per stem in A. syriaca and A. verticillata, and numbers of seeds per pod and seed weight in A. syriaca. Defoliation tended to result in a reduction of number of mature pods produced per stem. Results from shading showed a similar trend but few significant differences were observed.