Pterostylis australis (Southern Greenhood)

(unranked): Monocots
Order: Asparagales
Family: Orchidaceae
Subfamily: Orchidoideae
Tribe: Diurideae
Subtribe: Pterostylidinae
Genus: Pterostylis
Species: Pterostylis australis
Common name: Southern Greenhood

The New Zealand native genus Pterostylis is an interesting one in that it is distinctive by having flowers equipped with a mobile lip. This mobile lip is a pollination adaptation.  The pollinating insect lands on the flower and alights on the lip.  Its weight causes the lip to tip, forcing the insect into a position where it pollinates the flower.

Pterostylis australis is a  perennial herb forming large colonies through vegetative extension.  It develops erect smooth flowering stems up to 250 mm tall.  

More information at

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Thanks to Wikipedia for text and information: