Pterostylis mutica

Pterostylis mutica, commonly known as the midget greenhood, is a plant in the orchid family Orchidaceae and is endemic to Australia, occurring in all states but not the Northern Territory. There is a rosette of leaves at the base of the flowering stem and up to fifteen pale green flowers which have a sensitive labellum.

Labelled image of P. mutica

Midget greenhood
Pterostylis mutica growing near Lake King, Western Australia
Scientific classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Monocots
Order: Asparagales
Family: Orchidaceae
Subfamily: Orchidoideae
Tribe: Cranichideae
Genus: Pterostylis
Species:
P. mutica
Binomial name
Pterostylis mutica
Synonyms[1]

Description

Pterostylis mutica, is a terrestrial, perennial, deciduous, herb with an underground tuber. There is a rosette of between six and twelve, egg-shaped leaves, each leaf 10–30 mm (0.4–1 in) long and 5–15 mm (0.2–0.6 in) wide at the base of the plant. Between two and twenty well-spaced flowers are borne on a flowering spike 150–350 mm (6–10 in) high with five to ten stem leaves wrapped around it. The flowers are pale green, 8–10 mm (0.3–0.4 in) long and about 5 mm (0.2 in) wide. The dorsal sepal and petals are joined to form a hood called the "galea" over the column. The galea is curved with a pointed tip turning downwards. The lateral sepals turn downwards and are about 7 mm (0.3 in) long, 8 mm (0.3 in) wide, cupped and joined for most of their length. The labellum is about 4 mm (0.2 in) long, about 2 mm (0.08 in) wide and whitish-green with a dark green appendage. Flowering occurs from July to December.[2][3][4][5][6][7]

Taxonomy and naming

Pterostylis mutica was first formally described in 1810 by Robert Brown from a specimen collected near Port Jackson and the description was published in Prodromus Florae Novae Hollandiae et Insulae Van Diemen.[1] The specific epithet (mutica) is a Latin word meaning "shortened" or "docked"[8] referring to the blunt petals and sepals.[6]

Distribution and habitat

Pterostylis mutica is widespread and often common, growing in a wide range of habitats from near the coast to mountains, but usually in well-drained soil. It tolerates dry conditions, poor soil and exposed positions. It is widespread in New South Wales and Victoria and also occurs in south-east Queensland, south-eastern South Australia and the south-west of Western Australia. There is doubt about its presence in Tasmania[2][3][4][7][9][10]

Ecology

The labellum of P. mutica is attractive to a species of gnat which lands on the labellum and grasps the dark green appendage. When it does so, the labellum springs upward, trapping the insect inside the now-closed flower. The gnat can now only escape by pushing between "wings" on the sides of the column. As it does so, it either removes a pollinium or deposits one from a previously-visited flower of the same species, and pollination occurs.[11]

References

  1. "Pterostylis mutica". APNI. Retrieved 21 May 2017.
  2. Jones, David L. (2006). A complete guide to native orchids of Australia including the island territories. Frenchs Forest, N.S.W.: New Holland. p. 321. ISBN 978-1877069123.
  3. Jeanes, Jeff. "Pterostylis mutica". Royal Botanic Gardens Victoria: vicflora. Retrieved 13 May 2017.
  4. Jones, David L. "Pterostylis mutica". Royal Botanic Gardens Sydney: plantnet. Retrieved 21 May 2017.
  5. "Pterostylis mutica". State Herbarium of South Australia: eflora SA. Retrieved 21 May 2017.
  6. Brown, Andrew; Dundas, Pat; Dixon, Kingsley; Hopper, Stephen (2008). Orchids of Western Australia. Crawley, Western Australia: University of Western Australia Press. p. 374. ISBN 9780980296457.
  7. Hoffman, Noel; Brown, Andrew (2011). Orchids of South-West Australia (3rd ed.). Gooseberry Hill: Noel Hoffman. p. 418. ISBN 9780646562322.
  8. Brown, Roland Wilbur (1956). The Composition of Scientific Words. Washington, D.C.: Smithsonian Institution Press. p. 428.
  9. "Pterostylis mutica". FloraBase. Western Australian Government Department of Parks and Wildlife.
  10. Jones, David L. (1998). "A taxonomic review of Pterostylis in Tasmania". Australian Orchid Research. 3: 146–147.
  11. Cingel, Nelis A. van der (2000). An atlas of orchid pollination : America, Africa, Asia and Australia. Rotterdam: Balkema. p. 210. ISBN 978-9054104865.
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