Alexgeorgea, a remarkable Australian
The Flora of Australia is a marvellous thing.
This statement is true in two ways. The plant life of Australia is marvellous, and so is the Flora of Australia, a mammoth project to name and document all of Australia's plants. Originally begun as a print work in 60 volumes, the Flora of Australia is now online, and is growing rapidly. It currently includes around 15 000 of the estimated 25 000 species of flowering plants in Australia.
Among the species to be published recently in the Flora of Australia are the three species of a remarkable Western Australian genus, Alexgeorgea.
Named after eminent botanist and founding Executive Editor of the Flora of Australia Alex George, most visitors to Western Australia during wildflower season are unlikely to notice this remarkable plant, and are even less likely to notice its flowers.
Alexgeorgea is a member of the largely southern hemisphere family Restionaceae. Australia, particularly south-west Western Australia, is a global hotspot for this family, along with South Africa. Restiads are rush-like plants with leaves reduced to scales, and photosynthetic stems. In most species there are separate male and female plants, with pollen from the male flowers carried to the feathery stigmas of female flowers on the wind.
Most wind-pollinated plants have rather small, dull-coloured flowers, and this is true for restiads - only plants that need to attract birds or insects invest in bright colours and showy designs. But dull-looking plants can nevertheless be spectacular in their own way, and Alexgeorgea is an example, because, despite being wind-pollinated, the female flowers of Alexgeorgea are borne under the ground.
The female flowers of Alexgeorgea are so odd that It took over a century to discover them and work out how the plant lived its life.
The first species in the genus was named in 1846 by the German botanist Christian Gottfried Daniel Nees von Esenbeck, who gave it the name Restio nitens. He correctly interpreted and described the male flowers, but got the females completely wrong. A type of smut fungus frequently invades male flowers of this species, causing them to swell and grow abnormally. To von Esenbeck, these fungus-galled male flowers looked like female flowers with nuts, and he described them as such. For the next hundred years, smut-infected male plants were thought to be females, and no-one looked more closely
It was only in 1974 that Sherwin Carlquist, a Californian botanist on a visit to Western Australia, discovered the first females and named Alexgeorgea as a new, unique genus.
All other species of Restionaceae have female flowers on aerial stems, but in Alexgeorgea the female flowers are produced on short underground rhizomes. At flowering time, usually at the first rains of autumn, a long, slender, delicate, 3-branched style emerges briefly from the underground flower into the air to collect pollen, then withers. The fruit, a nut about 1 cm long (the largest in its family), later develops underground if the flower is successfully pollinated.
Plants spread clonally by long slender rhizomes, eventually forming very large patches, so the fruits are distributed by this growth, and possibly by animals burrowing in the sandy soil. Keeping your fruits underground would also serve to protect them from fire, and possibly other hazards such as grazing predators. It's also a great way to hide, for a hundred years or more, from the keen eyes of botanists.
In the Flora of Australia, the description of Alexgeorgea and its three species link to nomenclatural data, specimen records, distribution maps, images, descriptions and other information.
One species of Alexgeorgea, A. nitens, is very common in remnant Banksia woodlands in the suburbs of Perth If you live in or visit Western Australia in autumn, perhaps you can use the Flora of Australia to track it down, and become one of only a handful of people who have ever seen Alexgeorgea doing its thing.
Thanks to Restionaceae taxonomist Barbara Briggs from the National Herbarium of New South Wales for preparing this story.