Prasophyllum viretrum, commonly known as Orford leek orchid,[1] is a species of orchid endemic to Victoria. It has a single tubular, dark green leaf and up to thirty five scented, greenish-brown to brownish flowers and is only known from a few small populations in south-western Victoria.
Prasophyllum viretrum is a terrestrial, perennial, deciduous, herb with an underground tuber and a single dark green, tube-shaped leaf up to 300sigfig=1NaNsigfig=1 long and NaNsigfig=1NaNsigfig=1 wide. Between twelve and thirty five scented, greenish-brown to brownish flowers are arranged along a flowering spike NaNsigfig=1NaNsigfig=1 long, reaching to a height of NaNsigfig=1NaNsigfig=1. As with others in the genus, the flowers are inverted so that the labellum is above the column rather than below it. The dorsal sepal is egg-shaped to lance-shaped, NaNsigfig=1NaNsigfig=1 long and turned downwards. The lateral sepals are a similar length to the dorsal sepal, linear to lance-shaped and spread apart from each other. The petals are linear to lance-shaped and NaNsigfig=1NaNsigfig=1 long. The labellum is white, sometimes pinkish, about 7sigfig=1NaNsigfig=1 long, turns upwards near its middle and has crinkled or wavy edges. Flowering occurs from October to December.[2] [3]
Prasophyllum viretrum was first formally described in 2006 by David Jones and Dean Rouse from a specimen collected at the Pretty Hill Flora Reserve, near Orford and the description was published in Australian Orchid Research.[4] The specific epithet (viretrum) is derived from the Latin word viretum meaning "greensward", "sod" or "turf".[5]
This leek orchid grows in grassland in moist places and is only known from four or five populations near Warrnambool, Orford, Port Fairy and Mortlake in south-west of the state.
Prasophyllum viretrum is listed as "critically endangered" under the Victorian Government Flora and Fauna Guarantee Act 1988.