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 NaNsigfig=1NaNsigfig=1 long and NaNsigfig=1NaNsigfig=1 wide. Between two and eight dark reddish-brown flowers with transparent sections, each flower NaNsigfig=1NaNsigfig=1 long and NaNsigfig=1NaNsigfig=1 wide are borne on a flowering spike NaNsigfig=1NaNsigfig=1 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 NaNsigfig=1NaNsigfig=1 long. The lateral sepals are wider than the galea, dished, densely hairy on their outer edges and suddenly taper to thread-like tips NaNsigfig=2NaNsigfig=2 long and parallel to each other. The labellum is reddish-brown, thin and insect-like, NaNsigfig=1NaNsigfig=1 long and about 4sigfig=1NaNsigfig=1 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.[1] [2] [3]
Pterostylis maxima was first formally described in 1989 by David Jones and Mark Clements from a specimen collected near Bendigo and the description was published in Australian Orchid Research.[4] The specific epithet (maxima) is a Latin word meaning "greatest" or "largest".[5]
The large rustyhood occurs in scattered populations south from Temora in New South Wales and across Victoria to the south-east bioregion of South Australia. It grows in woodland, open forest and mallee.
Pterostylis maxima is described as "vulnerable" in Victoria and as "endangered" in South Australia.[6]