The Hordeum murinum Complex in Australia

Abstract

Barley grass (in Australia usually called Hordeum leporinum Link) was collected at 88 sites in South Australia and Victoria and grown at Northfield, near Adelaide, S.A. Time to Aowering was noted and each line was identified taxonomically. Specimens from the Australian herbaria were examined. The material was shown to belong to the three species within the Hordeum murinum complex. H. murinum L. itself is restricted to near Hobart, Tasmania, but H. leporinum grows widely through the wetter parts of southern Australia: it seems to grow commonly as far north as Sydney, and in South Australia and Victoria where the rainfall exceeds c. 425 mm. H. glaucum Steud., the third species in the complex and not previously recorded in Australia, was shown to be the common barley grass in the semiarid zone of the southern States (<425 mm of rain), and in wetter regions in northern New South Wales and southern Queensland. Both H. leporinum and H. glaucum showed wide ecotypic variation in regard to flowering time, and this was related to length of growing season in South Australia and Victoria. The relationship was closest in H. leporinum. The first specimens of both H. leporinum and H. glaucum were collected in the 1840s and 1850s. Thus both species were introduced into Australia well before the Suez Canal opened in 1869. This eliminates the eastern Mediterranean as a direct source of the H. murinum complex even though the European distribution of one member, H. glaucum, is apparently limited to that region. Four other possible origins-England, the Atlantic coast and islands of Europe and north Africa, South Africa, and India-are discussed in relation to the distribution of the species and their opportunities for being introduced.