Prasophyllum spadiceum, commonly known as the brown lip leek orchid, is a species of orchid endemic to southern continental Australia. It has a single tube-shaped leaf and up to thirty pale green, brown and white flowers with a whitish labellum. It is a recently described plant, previously included with P. fitzgeraldii, but distinguished from that species by its smaller, paler flowers, whitish labellum and brown callus. It grows in the south-east of South Australia and in a single location in western Victoria.
Prasophyllum spadiceum is a terrestrial, perennial, deciduous, herb with an underground tuber and a single tube-shaped, shiny, pale green leaf which is NaNsigfig=1NaNsigfig=1 long and NaNsigfig=1NaNsigfig=1 wide at the base. Between ten and thirty scented, mostly green flowers are well spaced along a flowering spike NaNsigfig=1NaNsigfig=1 long, reaching to a height of NaNsigfig=1NaNsigfig=1. The flowers are NaNsigfig=1NaNsigfig=1 long and NaNsigfig=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 lance-shaped to narrow egg-shaped, NaNsigfig=2NaNsigfig=2 long and about 2sigfig=1NaNsigfig=1 wide. The lateral sepals are egg-shaped to lance-shaped, NaNsigfig=2NaNsigfig=2 long, NaNsigfig=1NaNsigfig=1 wide, free and slightly spreading from each other. The petals are brown with whitish edges, oblong, NaNsigfig=2NaNsigfig=2 long and about 2sigfig=1NaNsigfig=1 wide. The labellum is whitish, oblong to egg-shaped, NaNsigfig=2NaNsigfig=2 long, NaNsigfig=2NaNsigfig=2 wide and turns sharply upward at 90° about half-way along. The upturned part is wavy or crinkled on the edges. There is a lance-shaped to egg-shaped, coffee-coloured callus in the centre of the labellum and extending almost to its tip. Flowering occurs in October.[1] [2]
Prasophyllum spadiceum was first formally described in 2017 by David Jones and Robert Bates and the description was published in Australian Orchid Review from a specimen collected in the Gum Lagoon Conservation Park.[3] The specific epithet (spadiceum) is a Latin word meaning "reddish-brown",[4] referring to the colour of the callus.
The brown lip leek orchid mostly grows in damp heathy woodland and is found in the mid south-east of South Australia and in a single location with about 100 plants near Apsley in far western Victoria.