Sex ratios in New Zealand apioid Umbelliferae

Abstract

Sex ratios are reported for 53 populations of species of Gingidia, Scandia, Lignocarpa, Anisotome, and Aciphylla (Umbelliferae, Apioideae). In 43 populations there is a significant preponderance of male plants; in 6 populations the sexes are approximately equally common, and in 4 no females were found.The ratio (male/female) of the average number of inflorescences per plant is significantly correlated with the average number of inflorescences per plant (male and female averages combined) in dioecious but not in gynodioecious species. This result indicates that populations with higheraverage inflorescence numbers per plant are able to use inflorescence number as part of sex differential strategies for optimally deploying reprodutive effort.The results are consistent with a hypothesis of greater cost of reproduction to females than to males, resulting in differential longevity of the sexes. © 1980 Taylor & Francis Group, LLC.