Botanic Gardens Trust, Sydney, Australia


A new close relative of the grasses - the third species of Ecdeiocoleaceae

Barbara G. Briggs - Honorary Research Associate

The plant family Ecdeiocoleaceae was recently found, by DNA studies here at the Royal Botanic Gardens & Domain Trust, to be one of the closest relatives of the grasses, the Poaceae, indeed probably their closest living relatives. This has given unexpected interest in these plants of infertile soils and arid environments in the southern half of Western Australia, since grasses are the most important sources of food for humans and other animals.

As a sister-group to the grasses, Ecdeiocoleaceae must have a long history. It is remarkable that it has so few species and such a limited distribution, in contrast to the thousands of species of grasses worldwide.

Only two species of Ecdeiocoleaceae were known, one each in the genera Ecdeiocolea and Georgeantha. Field studies by Barbara Briggs with Patricia Meagher and with Russell Barrett of Kings Park & Botanic Garden, Perth, have confirmed that there is a further species of Ecdeiocolea. It is distinguished from the widespread species by its extensive rhizomes, rigid stems and larger size. The two species grow together with no sign of hybridisation.

A description of the new species has been prepared, so that it can be formally named. In addition to collecting and describing this species, Barbara is studying the reproduction of Ecdeiocolea. Both species are unusual in having zones of male and female flowers in the inflorescence and a pattern of synchronous flowering of either male or female flowers on the plant at any one time. This is an effective method of promoting outcrossing between these wind-pollinated plants.





Barbara digging tussocks to study the rhizomes of the new species, north of Geraldton. Photo: Patricia Meagher

Ecdeiocolea monostachya - male flowers of  with yellow anthers. Photo: Patricia Meagher

E. monostachya - female flowers with feathery white stigmas. Photo: Patricia Meagher