• Home
»
• Plant of the Season
»
• Autumn
»
• Pterostylis obtusa R. Br.

Click on image for larger view

Below the Visitors Centre, half way between the first water feature and the Brunet Meadow there is a junction dividing the African section of the Rock Garden from the Proteaceae section. Here, you may easily admire a grouping of about seven of these small, native, terrestrial greenhood orchids. The lower area of the Gondwana Walk is also home to this species. There, often in dappled light and among grasses, they can be much harder to see.

Because the rostellum, or beak-like outgrowth on the flower, has hatchet-shaped wings on either side, the Greek words, pteron, (wing) and stylis, (column) were used to describe this 120 member genus commonly called greenhoods. About 100 species occur in Australia with the balance in New Zealand, New Caledonia or New Guinea.

Male fungus gnats and male mosquitoes have been observed as pollinators of some Pterostylis species. It seems most likely then, that the whole genus is pollinated by pseudocopulation. Male insects, lured probably by scent, trigger a spring trap within the flower and can only escape by brushing past the stigma and anther, thus effecting pollination. Dr Rod Peakall’s team at the Australian National University, Canberra, is currently investigating this poorly documented phenomenon of pollinated by sexual deception in the genus Pterostylis.

Flowering from February to June, Pterostylis obtusa, the Blunt-tongue Greenhood is often encountered among grass on moist slopes on ridges and in the ranges and tablelands of New South Wales. Many orchid species are protected in the wild.

A cluster of terrestrial orchids in a pot or as a feature in a native garden is quite appealing. If you are ready for this horticultural challenge, the Blunt-tongue Greenhood is said to be one of the easier species for beginners. To obtain correctly identified plants and to ensure that you do not impinge on wild stock, also for good growing advice, we suggest you contact the Australasian Native Orchid Society at: ANOS - PO Box 318 Willoughby NSW 2068, or phone (Sydney) 02 9416 4306 or (Wollongong) 02 4229 9751.

Jan Allen
Garden Information Officer