Pterostylis exserta

Pterostylis exserta, commonly known as the exserted rufous greenhood, is a species of orchid endemic to the south-west of Western Australia. Both flowering and non-flowering plants have a large rosette of leaves flat on the ground and flowering plants have up to seven pale, transparent green and white flowers with brownish lines.

Exserted rufous greenhood
Scientific classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Monocots
Order: Asparagales
Family: Orchidaceae
Subfamily: Orchidoideae
Tribe: Cranichideae
Genus: Pterostylis
Species:
P. exserta
Binomial name
Pterostylis exserta
(D.L.Jones D.L.Jones[1]
Synonyms[2]

Oligochaetochilus exsertus D.L.Jones

Description

Pterostylis exserta is a terrestrial, perennial, deciduous, herb with an underground tuber and a rosette of leaves 20–70 mm (0.8–3 in) in diameter. Flowering plants have up to seven, well-spaced flowers 30–40 mm (1–2 in) long and 6–7 mm (0.2–0.3 in) wide on a flowering stem 100–350 mm (4–10 in) high. The flowers are transparent green and white with brownish veins. The dorsal sepal and petals are fused, forming a hood or "galea" over the column. The lateral sepals turn downwards and suddenly taper to narrow, thread-like tips which spread apart from each other. The labellum is brown, insect-like and stands out from the lateral sepals, with many short hairs on the "head" end and longer bristles on the side of the "body". Flowering occurs from lae August to October.[3][4]

Taxonomy and naming

The exserted rufous greenhood was first formally described in 2015 by David Jones and given the name Oligochaetochilus exsertus.[5] The description was published in Australian Orchid Review from a specimen collected near Gunyidi. In 2015 David Jones changed the name to Pterostylis exserta "to allow for the different taxonomic views held at generic level within the subtribe". The species had previously been known as Pterostylis sp. 'exserted labellum'.[1] The specific epithet (exserta) is a Latin word meaning "projecting" or "thrust forth",[6] referring to the way the labellum is raised above the lateral sepals.[1]

Distribution and habitat

The exserted rufous greenhood grows in shrubland, mallee woodland, and near granite outcrops between Eneabba and Hyden in the Avon Wheatbelt, Geraldton Sandplains and Mallee biogeographic regions.[3][4][7]

Conservation

Pterostylis exserta is classified as "not threatened" by the Western Australian Government Department of Parks and Wildlife.[7]

References
  1. "Pterostylis exserta". APNI. Retrieved 27 July 2017.
  2. "Pterostylis exserta". World Checklist of Selected Plant Families (WCSP). Royal Botanic Gardens, Kew.
  3. Brown, Andrew; Dixon, Kingsley; French, Christopher; Brockman, Garry (2013). Field guide to the orchids of Western Australia : the definitive guide to the native orchids of Western Australia. Simon Nevill Publications. p. 378. ISBN 9780980348149.
  4. Hoffman, Noel; Brown, Andrew (2011). Orchids of South-West Australia (3rd ed.). Gooseberry Hill: Noel Hoffman. p. 444. ISBN 9780646562322.
  5. "Oligochaetochilus exsertus". APNI. Retrieved 27 July 2017.
  6. Brown, Roland Wilbur (1956). The Composition of Scientific Words. Washington, D.C.: Smithsonian Institution Press. p. 633.
  7. "Pterostylis exserta". FloraBase. Western Australian Government Department of Parks and Wildlife.
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