Prasophyllum regium, commonly known as the king leek orchid, is a species of orchid endemic to the south-west of Western Australia. It has a single, unusually thick tubular leaf and up to one hundred relatively large, greenish-brown or burgundy-coloured flowers. It is one of the tallest leek orchids, sometimes growing to a height of 2sigfig=1NaNsigfig=1.
Prasophyllum regium is a terrestrial, perennial, deciduous, herb with an underground tuber and a single fleshy, green to blackish, tube-shaped leaf NaNsigfig=1NaNsigfig=1 long and NaNsigfig=1NaNsigfig=1 wide. Between fifty and one hundred or more flowers are arranged along a flowering spike NaNsigfig=1NaNsigfig=1 long, reaching to a height of NaNsigfig=1NaNsigfig=1. The flowers are greenish-brown to burgundy-coloured, NaNsigfig=1NaNsigfig=1 long and about 15sigfig=1NaNsigfig=1 wide. 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 NaNsigfig=1NaNsigfig=1 long and NaNsigfig=2NaNsigfig=2 wide and the lateral sepals are NaNsigfig=1NaNsigfig=1 long, NaNsigfig=1NaNsigfig=1 wide and fused to each other. The petals are NaNsigfig=1NaNsigfig=1 long, 3sigfig=1NaNsigfig=1 wide and curve forwards. The labellum is NaNsigfig=1NaNsigfig=1 long, NaNsigfig=2NaNsigfig=2 wide and turns sharply upwards near its middle, the upturned part with crinkled to wavy edges. A fleshy, shiny green callus covers most of the labellum, reaching almost to its tip. Flowering occurs from September to December.[1] [2] [3]
Prasophyllum regium was first formally described in 1918 by Richard Sanders Rogers from a specimen collected near Manjimup and the description was published in Transactions, proceedings and report, Royal Society of South Australia.[4] [5] The specific epithet (regium) is a Latin word meaning "kingly" or "royal"[6] referring to the tall flowering stem.
The king leek orchid is found between Perth and Albany in the Jarrah Forest, Swan Coastal Plain and Warren biogeographic regions, growing in a wide range of habitats from seasonal swamps to dense forests.
Prasophyllum regium is listed as "Not Threatened" by the Western Australian Government Department of Parks and Wildlife.