Testing the Fertility and Allelopathic Abilities of Arctotheca prostrata (Salisb.) Britten (Asteraceae, Arctotideae), a South African Plant Species that has Naturalized in California.

摘要

Arctotheca prostrata is a perennial plant species native to South Africa that reproduces vegetatively by long runners. In South Africa it also reproduces sexually, producing fruits with fertile seeds. The species was brought to California to serve as a ground cover but fruits had not been reported. Historically, it has been said to be infertile. This study tested the fertility of A. prostrata in California by crossing plants from California with each other and with plants grown from imported South African seeds. Pollen viability was tested and morphological measures were made on heads, leaves, and pollen. Mean Californian and South African measurements were compared by nested analysis of variance (ANOVA). Earlier research indicated that A. prostrata is allelopathic. Lettuce seeds were germinated for 72 hours in extracts containing different amounts of ground leaves, runners, and roots of A. prostrata to test for allelopathic abilities. My study found that A. prostrata from California is outcrossing and fertile. It does not differ much, if at all, in morphology from South African individuals in the study. It is allelopathic. My results suggested that plants from California have a stronger allelopathic effect on lettuce seedling growth than plants from South Africa. Currently, naturalized populations of A. prostrata in California are rare. However, if populations increase in number and begin to produce seeds, the species has the potential to become invasive.