Microtis alba, commonly known as the white mignonette orchid or slender onion-orchid, is a species of orchid endemic to the south-west of Western Australia. It has a single hollow, onion-like leaf and up to sixty small, green and white flowers with a strong musky fragrance. It is much more common after a fire the previous summer than in unburned country.
Microtis alba is a terrestrial, perennial, deciduous, herb with an underground tuber and a single erect, smooth, tubular leaf NaNsigfig=1NaNsigfig=1 long and NaNsigfig=1NaNsigfig=1 wide. Between ten and sixty green and white flowers are arranged along a flowering stem NaNsigfig=1NaNsigfig=1 tall. The flowers have a strong musky fragrance, lean downwards and are NaNsigfig=1NaNsigfig=1 long and NaNsigfig=1NaNsigfig=1 wide. The dorsal sepal is NaNsigfig=2NaNsigfig=2 long, about 2sigfig=1NaNsigfig=1 wide and forms a hood over the column. The lateral sepals are NaNsigfig=1NaNsigfig=1 long, about 1sigfig=1NaNsigfig=1 wide with their tips rolled under. The petals are NaNsigfig=1NaNsigfig=1 long, about 1sigfig=1NaNsigfig=1 wide and often curved. The labellum is oblong to wedge-shaped, NaNsigfig=1NaNsigfig=1 long, NaNsigfig=1NaNsigfig=1 wide with wrinkled edges and a notched tip. Flowering occurs from October to January but much more prolifically after fire the previous summer.[1] [2] [3]
Microtis alba was first formally described by Robert Brown in 1810 and the description was published in Prodromus Florae Novae Hollandiae et Insulae Van Diemen.[4] [5] The specific epithet (alba) is a Latin word meaning "white".[6]
The white mignonette orchid grows in a range of habitats from seasonally wet flats to forest and occurs between Dongara and Israelite Bay.
Microtis alba is classified as "not threatened" by the Western Australian Government Department of Parks and Wildlife.