Pterostylis hamiltonii, commonly known as the red-veined shell orchid, is a species of orchidendemic to the south-west of Western Australia. As with similar orchids, the flowering plants differ from those which are not flowering. The non-flowering plants have a rosette of leaves but the flowering plants lack a rosette and have a single flower with leaves on the flowering spike. This greenhood has a green and white, striped flower with reddish-brown markings and forms colonies, sometimes of thousands of plants.
Description
Pterostylis hamiltonii is a terrestrial, perennial, deciduous, herb with an underground tuber and when not flowering, a rosette of bluish-green leaves, each leaf 5–14 mm long and 5–12 mm wide. Flowering plants usually have a single flower 25–30 mm long and 12–15 mm wide borne on a spike 50–150 mm high with four to six stem leaves 20–40 mm long and 2–8 mm wide. The flowers are white with green or reddish-brown stripes and markings. The dorsal sepal and petals are fused, forming a hood or "galea" over the column. The dorsal sepal curves forward with a thread-like tip 1–3 mm long. The lateral sepals are erect and held closely against the galea. They have thread-like ends 20-25 long and between their bases there is a broad, flat sinus with a central notch. The labellum is 15–20 mm long, about 3 mm wide, dark red and curved and protrudes above the sinus. Flowering occurs from late May to early August.[2][3][4][5]
^ abJones, David L. (2006). A complete guide to native orchids of Australia including the island territories. Frenchs Forest, N.S.W.: New Holland. pp. 291–292. ISBN978-1877069123.
^ abBrown, Andrew; Dundas, Pat; Dixon, Kingsley; Hopper, Stephen (2008). Orchids of Western Australia. Crawley, Western Australia: University of Western Australia Press. p. 347. ISBN9780980296457.
^ abHoffman, Noel; Brown, Andrew (2011). Orchids of South-West Australia (3rd ed.). Gooseberry Hill: Noel Hoffman. p. 397. ISBN9780646562322.