Genoplesium nigricans

Genoplesium nigricans, commonly known as mallee midge orchid, is a species of orchid endemic to Australia. It is a terrestrial herb with a single leaf mostly surrounding the stem, and up to 50 tiny, greenish flowers with a deep maroon-coloured labellum and often have a fruity fragrance. Australian authorities use the name Corunastylis tepperi, a widespread species which has been confused with Corunastylis nigricans, a species with purplish brown flowers and which only occurs on Kangaroo Island and the Eyre Peninsula.[2]

Mallee midge orchid
Scientific classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Monocots
Order: Asparagales
Family: Orchidaceae
Subfamily: Orchidoideae
Tribe: Diurideae
Genus: Genoplesium
Species:
G. nigricans
Binomial name
Genoplesium nigricans
Synonyms[1]
  • Prasophyllum tepperi F.Muell. ex Tepper
  • Corunastylis tepperi (F.Muell ex Tepper) D.L.Jones & M.A.Clem.

Description

Genoplesium nigricans is a terrestrial, perennial, deciduous, sympodial herb. A single long leaf surrounds the stem from the base of the plant to the lowest of the flowers. The leaf is 80–250 mm (3–10 in) long and 1–2 mm (0.04–0.08 in) wide.[2][3][4][5]

The inflorescence is a spike with from 5 to 50 crowded, tiny, non-resupinate flowers which are bright green with a dark maroon-coloured to purplish-black labellum. Each flower is pendulous, about 3 mm (0.1 in) wide and long with petals and sepals that do not spread widely. The dorsal sepal is a broad egg-shape, about 2 mm (0.08 in) long and wide. The two lateral sepals are lance-shaped, 2.5–3.5 mm (0.098–0.14 in) long and about 1 mm (0.04 in) wide and dished near their base. The petals are egg-shaped, about 2 mm (0.08 in) long and less than 1 mm (0.04 in) wide. The dark-coloured labellum is egg-shaped, about the same size as the petals with a minutely wavy edge. The callus is narrow egg-shaped and extends almost to the tip of the labellum. The column, which is below the labellum has wings with a rough surface. Flowering occurs between February and May and the fruit that follows is a non-fleshy, dehiscent capsule containing hundreds of seeds.[2][5]

Taxonomy and naming

In 1880, Otto Temper, a South Australian school teacher, reported to the Royal Society of South Australia, the discovery he had made of an orchid "in respect of which Baron F. v. Mueller, has done me the honour of naming it Prasophyllum Tepperi".[6][7] Tepper's description was formalised by Ferdinand von Mueller in 1882 with the name published in Systematic Census of Australian Plants.[8][9]

In 2002, David Jones and Mark Clements changed the name of Prasophyllum tepperi to Corunastylis tepperi.[1] The World Checklist of Selected Plant Families lists C. tepperi as a synonym of Genoplesium nigricans.[10] The specific epithet (tepperi) honours Otto Tepper[7] and the epithet nigricans is a Latin word meaning "blackish".[11]

Corunastylis nigricans, a different species, sometimes confused with Genoplesium nigricans or Corunastylis tepperi, has purplish brown flowers with green markings and a shiny, dark purplish labellum and only occurs in parts of South Australia.[2]

Distribution and habitat

The mallee midge orchid occurs in arid areas of north-western Victoria, mostly in mallee shrubland and Callitris woodland,[2] and in the Avon Wheatbelt, Coolgardie, Esperance Plains, Hampton and Mallee biogeographic regions of southern Western Australia.[12] There are also isolated populations in South Australia.[13] It is a very drought and heat tolerant species which is dormant when the soil is hard-packed and dry, growing and flowering in the cooler, wetter autumn months.

Ecology

This species appears to be pollinated by tiny fruit flies which are attracted by the scent of the flower at the same time as other plants, such as Leucopogon are flowering.[5][14][15]

References
  1. "Corunastylis tepperi". APNI. Retrieved 1 January 2018.
  2. Jeanes, Jeff. "Corunastylis tepperi". Royal Botanic Garden Victoria: Vicflora. Retrieved 13 July 2016.
  3. Jones, David L. (2006). A complete guide to native orchids of Australia including the island territories. Frenchs Forest, N.S.W.: New Holland. pp. 189–190. ISBN 1877069124.
  4. Brown, Andrew; Dundas, Pat; Dixon, Kingsley; Hopper, Stephen (2008). Orchids of Western Australia. Crawley, Western Australia: University of Western Australia Press. pp. 168–169. ISBN 9780980296457.
  5. Hoffman, Noel; Brown, Andrew (2011). Orchids of South-West Australia (3rd ed.). Gooseberry Hill: Noel Hoffman. pp. 351–352. ISBN 9780646562322.
  6. "Prasophyllum tepperi". APNI. Retrieved 1 January 2018.
  7. Tepper, Otto (1880). "On the characteristics and distribution of the native and naturalised plants about Ardrossan, Yorke's Peninsula". Transactions and proceedings and report, Royal Society of South Australia. 3: 32–33. Retrieved 13 July 2016.
  8. "Prasophyllum tepperi". APNI. Retrieved 1 January 2018.
  9. von Mueller, Ferdinand (1882). Systematic Census of Australian Plants. Melbourne. p. 140. Retrieved 1 January 2018.
  10. "Corunastylis tepperi". World Checklist of Selected Plant Families (WCSP). Royal Botanic Gardens, Kew.
  11. Brown, Roland Wilbur (1956). The Composition of Scientific Words. Washington, D.C.: Smithsonian Institution Press. p. 46.
  12. "Corunastylis tepperi". FloraBase. Western Australian Government Department of Parks and Wildlife.
  13. "Corunastylis tepperi". Atlas of Living Australia. Retrieved 13 July 2016.
  14. Archer, William. "Corunastylis tepperi - Pygmy Orchid". Experance Wildflowers. Retrieved 13 July 2016.
  15. Bates, Robert J. "Murray Mallee Midges Autumn 2011". Native Orchid Society of South Australia. Retrieved 13 July 2016.
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