Pterostylis australis (Southern Greenhood)
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 http://www.nzpcn.org.nz/c/flora/factsheets/NZPCN_Species_1209.pdf
Thanks to Wikipedia for text and information: https://creativecommons.org/licenses/by-sa/3.0/