Relationships among taxa of Elymus (Poaceae: Triticeae) in Australia: reproductive biology

Abstract

Nomenclatural and taxonomic problems are common among members of the tribe Triticeae and in particular the genus Elymus L. For the Australian representatives of this genus, confusion surrounds the number of taxa present, and which literature belongs to which 'taxon'. The literature indicates at least four major taxa: (1) long-awned forms of E. scaber var. scaber equated to E. rectisetus, (2) shorter-awned forms of E. scaber var. scaber, (3) the very short-awned E. multiflorus and (4) E. scaber var. plurinervis. In addition, a form intermediate between the long- and short-awned forms of E. scaber, as well as populations containing polymorphic forms have been reported. A recent taxonomic treatment of the species complex identified a fifth taxon, E. sp. A. This taxon has previously been identified as E. scaber or E. multiflorus. The current study examined 500 pistils from megaspore mother cell to mature embryo sac, somatic and haploid chromosome numbers, and seed set of nine populations of E. scaber var. scaber sensu lato (common wheatgrass). They included forms equating to E. rectisetus, E. scaber and E. sp. A, a population with intermediate characteristics, and three polymorphic populations. Taxon (1) above is apomictic; taxon (2) contains two entities, one a facultative apomict encompassing the intermediate and polymorphic populations, and the other, the sexual E. sp. A. Exclusive sexuality was also confirmed for material of (3) and (4).