Microtis atrata, commonly known as the swamp mignonette orchid[2] or yellow onion orchid[3] and sometimes as Microtidium atratum,[4] is a species of orchid endemic to southern Australia. It has a single thin leaf and up to forty or more yellowish-green flowers. The flowers are the smallest of any Australian ground-dwelling orchid. The orchid usually grows in large colonies after fire and although small, are easily seen because of their very large numbers in their blackened surroundings.
| Swamp mignonette orchid | |
|---|---|
Scientific classification 
| |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Monocots |
| Order: | Asparagales |
| Family: | Orchidaceae |
| Subfamily: | Orchidoideae |
| Tribe: | Diurideae |
| Genus: | Microtis |
| Species: | M. atrata
|
| Binomial name | |
| Microtis atrata | |
| Synonyms[1] | |
Description edit
Microtis atrata is a terrestrial, perennial, deciduous, herb with an underground tuber and a single erect, smooth, more or less solid leaf, 30–90 mm (1–4 in) long and about 3 mm (0.1 in) wide. Between two and forty or more yellowish-green flowers are densely crowded along a flowering stem 10–40 mm (0.4–2 in) long, reaching to a height of 50–120 mm (2–5 in). The plants are sometimes up to 200 mm (8 in) tall if growing in water. At about 2 mm (0.08 in) long and wide, the flowers are the smallest of any terrestrial Australian orchid, and as they age, they turn black. The dorsal sepal is egg-shaped to round, about 1 mm (0.04 in) long and wide and forms a hood over the column. The lateral sepals are oblong, less than 1 mm (0.04 in) long and spread apart from each other. The petals are egg-shaped and concave and the labellum is oblong to egg-shaped. Flowering occurs from September to December and is stimulated by fire the previous summer.[2][3][4][5]
Taxonomy and naming edit
Microtis atrata was first formally described in 1840 by John Lindley and the description was published in A Sketch of the Vegetation of the Swan River Colony.[6][7] The specific epithet (atrata) is a Latin word meaning "dressed in black",[8] referring to the colour of the dried flowers.[9]
Some authorities give this species the name Microtidium atratum[2][4] but this name is not widely accepted.[1][3]
Distribution and habitat edit
The swamp mignonette orchid occurs in the south-west of Western Australia, the south-east of South Australia, in southern Victoria and northern Tasmania. It grows in swampy places and in winter-wet depressions, sometimes in standing water and can form colonies of enormous numbers of plants after summer fire.[5][9][10]
Conservation edit
Microtis atrata is classified as "not threatened" in Western Australia by the Western Australian Government Department of Parks and Wildlife,[11] but is regarded as "endangered" in South Australia[12] and as "rare" in Tasmania.[4]
References edit
- ^ a b c "Microtis atrata". World Checklist of Selected Plant Families (WCSP). Royal Botanic Gardens, Kew.
- ^ a b c Jones, David L. (2006). A complete guide to native orchids of Australia including the island territories. Frenchs Forest, N.S.W.: New Holland. p. 221. ISBN 1877069124.
- ^ a b c Jeanes, Jeff. "Microtis atratum". Royal Botanic Gardens Victoria. Retrieved 19 February 2018.
- ^ a b c d "Microtidium atratum". Tasmanian Government Department of Primary Industries, Parks, Water and Environment. Retrieved 19 February 2018.
- ^ a b Brown, Andrew; Dundas, Pat; Dixon, Kingsley; Hopper, Stephen (2008). Orchids of Western Australia. Crawley, Western Australia: University of Western Australia Press. p. 280. ISBN 9780980296457.
- ^ "Microtis atrata". APNI. Retrieved 19 February 2018.
- ^ Lindley, John (1840). A Sketch of the Vegetation of the Swan River Colony. Piccadilly, London: James Ridgway. p. 52. Retrieved 19 February 2018.
- ^ Brown, Roland Wilbur (1956). The Composition of Scientific Words. Washington, D.C.: Smithsonian Institution Press. p. 110.
- ^ a b Hoffman, Noel; Brown, Andrew (2011). Orchids of South-West Australia (3rd ed.). Gooseberry Hill: Noel Hoffman. p. 335. ISBN 9780646562322.
- ^ Archer, William (28 August 2008). "Swamp mignonette orchid - Microtis atrata". Esperance Wildflowers. Retrieved 19 February 2018.
- ^ "Microtis atrata". FloraBase. Western Australian Government Department of Biodiversity, Conservation and Attractions.
- ^ "Microtis atrata - yellow onion orchid" (PDF). Government of south Australia Department for Environment and Heritage. Retrieved 19 February 2018.
External links edit
Data related to Microtis atrata at Wikispecies
