Microtis oblonga, commonly known as the sweet onion orchid, is a species of orchid endemic to south-eastern Australia. It has a single hollow, onion-like leaf and up to fifty scented, bright green flowers. It is considered by some Australian authorities to be synonymous with Microtis rara.
Microtis oblonga 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 fifty bright green, sweetly scented flowers are arranged along a flowering stem NaNsigfig=1NaNsigfig=1 tall. The flowers are NaNsigfig=2NaNsigfig=2 long and NaNsigfig=1NaNsigfig=1 wide. The dorsal sepal is more or less erect, about 3sigfig=1NaNsigfig=1 long and wide. The lateral sepals are 3sigfig=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 usually curve forwards. The labellum is oblong, NaNsigfig=2NaNsigfig=2 long, NaNsigfig=1NaNsigfig=1 wide with irregular edges and turns downward towards the ovary. There is a raised, dark green callus in the centre of the labellum. Flowering occurs from October to February.[1]
Microtis oblonga was first formally described in 1923 by Richard Sanders Rogers and the description was published in Transactions and Proceedings of the Royal Society of South Australia.[2] [3] It is regarded by many Australian authorities as being a synonym of Microtis rara.[4] [5] [6] The specific epithet (oblonga) is a Latin word meaning "longer than broad".[7]
The sweet onion orchid grows between grasses and shrubs in open forest from Gympie in Queensland south through New South Wales, Victoria and Tasmania and west to south-eastern South Australia.