A review of the classification and taxonomic and geographic distribution of cleistogamy in Australian grasses

Abstract

Cleistogamy, self-fertilisation within a closed flower, was found in 135 Australian grass species from 46 genera within 5 subfamilies representing 14% of the species and 30% of the genera. This represents an increase from 4% of species and 12% of genera from previous records. Expressions of cleistogamy were classified into three main categories on the basis of: presence or absence of anther dimorphism, presence of amphigamy with or without spikelet peculiarities, and chasmogamous and cleistogamous spikelets on separate plants. One category of these dimorphisms involves species that have differing terminal and axillary inflorescences (amphigamy) with corresponding spikelets so different that the axillary ones appear to belong to a different genus. Dimorphisms within cleistogamous species were found in inflorescences, spikelets, florets, anthers and caryopses. The highest concentration of Australian cleistogamous grasses occurs in the subtropical climatic zone and more than three-quarters of the species are chloridoid and panicoid with nearly equal proportions. Of Australian cleistogamous grasses, 33% have C3 photosynthetic pathway and 67% have C4, and the largest taxonomic groups are panicoid with 38% and chloridoid with 39%.