Large rustyhood

Description

Pterostylis maxima, commonly known as the large rustyhood, is a plant in the orchid family Orchidaceae and is endemic to south-eastern Australia. It has a rosette of leaves at its base and up to eight relatively large, dark brown flowers with transparent "windows" and a thin, dark insect-like labellum. Pterostylis maxima, is a terrestrial, perennial, deciduous, herb with an underground tuber. It has a rosette of between six and twelve egg-shaped leaves at the base of the flowering spike, each leaf 15–45 mm (0.6–2 in) long and 10–18 mm (0.4–0.7 in) wide. Between two and eight dark reddish-brown flowers with transparent sections, each flower 35–60 mm (1–2 in) long and 12–14 mm (0.5–0.6 in) wide are borne on a flowering spike 200–350 mm (8–10 in) tall. Four to six stem leaves are wrapped around the flowering spike. The dorsal sepal and petals are joined to form a hood called the "galea" over the column with the dorsal sepal having a thread-like tip 7–12 mm (0.3–0.5 in) long. The lateral sepals are wider than the galea, dished, densely hairy on their outer edges and suddenly taper to thread-like tips 25–35 mm (0.98–1.4 in) long and parallel to each other. The labellum is reddish-brown, thin and insect-like, 6–8 mm (0.2–0.3 in) long and about 4 mm (0.2 in) wide. The "head" end is swollen with two long bristles and there are up to 8 to 12 shorter bristles on each side of the "body". Flowering occurs from October to November. Pterostylis is a genus of about 300 species of plants in the orchid family, Orchidaceae. Commonly called greenhood orchids, they are terrestrial, deciduous, perennial, tuberous, herbs found in Australia, New Zealand, New Guinea, New Caledonia and one Indonesian island. The flowers are mostly green, sometimes with brown, reddish or white stripes, and are distinguished from other orchids by their unusual flower structures and pollination mechanism. Greenhood orchids are all terrestrial herbs with an underground tuber like many other genera of orchids but are distinguished by a hood-like "galea" formed by the fusing of the dorsal sepal and two lateral petals. The galea curves forward, covers the sexual parts of the flower, is important in the pollination process and is about as long as the two petals. The dorsal sepal is translucent white with green, reddish or brown stripes.