Chromosome Numbers and Genetic Systems in the Trigger Plants of Western Australia (Stylidium; Stylidiaceae)

Abstract

Chromosome numbers for 116 taxa of the genus Stylidium in south Western Australia are reported. The primitive number is n = 15, but haploid numbers ranging from 5 to 16 occur, with polyploidy on 13, 14 and 15. This dysploid variation is associated with a widespread occurrence of recessive lethal factors which eliminate most of the products of self-pollination at or soon after fertilization while permitting a majority of the cross-pollination products to survive.