Pterostylis sinuata

Pterostylis sinuata, commonly known as the Northampton midget greenhood or western swan greenhood, is a species of orchid endemic to the south-west of Western Australia. Both flowering and non-flowering plants have a rosette of leaves lying flat on the ground and flowering plants have up to twenty yellowish-green flowers. It is only known from a small area between Northampton and Kalbarri.

Northampton midget greenhood
Scientific classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Monocots
Order: Asparagales
Family: Orchidaceae
Subfamily: Orchidoideae
Tribe: Cranichideae
Genus: Pterostylis
Species:
P. sinuata
Binomial name
Pterostylis sinuata
Synonyms[2]

Hymenochilus sinuatus D.L.Jones

Description

Pterostylis sinuata, is a terrestrial, perennial, deciduous, herb with an underground tuber. It has a rosette of wavy-edged leaves 30–40 mm (1–2 in) in diameter lying flat on the ground. Between two and twenty or more yellowish-green flowers 5–6 mm (0.20–0.24 in) long and wide are arranged on a flowering spike 50–100 mm (2–4 in) high. The dorsal sepal and petals are joined to form a hood called the "galea" over the column. The dorsal sepal is gently curved but suddenly curves downward near the tip and is about the same length as the petals. The lateral sepals turn downwards and are joined for most of their length forming a cup shape. The labellum is small, green and cup-shaped. Flowering occurs from August to early September.[3][4][5]

Taxonomy and naming

The Northampton midget greenhood was first formally described in 2009 by David Jones from a specimen collected near Port Gregory. It was given the name Hymenochilus sinuatus and the description was published in The Orchadian.[6] In 2010 Jasmine Janes and Marco Duretto changed the name to Pterostylis sinuata.[1] The specific epithet (sinuata) is a Latin word meaning "bent" or "curved"[7] referring to the wavy edges of the leaves.[3]

Distribution and habitat

Pterostylis sinuata grows in moist depression, in open areas and flowering reduces when shrubland invades. It is only known from five populations between Northampton and Kalbarri in the Geraldton Sandplains biogeographic region.[3][5][8]

Conservation

Pterostylis sinuata is classified as "Threatened Flora (Declared Rare Flora — Extant)" by the Western Australian Government Department of Parks and Wildlife[8] and as "Endangered" (EN) under the Australian Government Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act). The main threats to the species are weed invasion, erosion, road and firebreak maintenance, grazing, inappropriate fire regimes and chemical drift.[5]

References
  1. "Pterostylis sinuata". APNI. Retrieved 17 July 2017.
  2. "Pterostylis sinuata". World Checklist of Selected Plant Families (WCSP). Royal Botanic Gardens, Kew.
  3. Brown, Andrew; Dundas, Pat; Dixon, Kingsley; Hopper, Stephen (2008). Orchids of Western Australia. Crawley, Western Australia: University of Western Australia Press. p. 376. ISBN 9780980296457.
  4. Hoffman, Noel; Brown, Andrew (2011). Orchids of South-West Australia (3rd ed.). Gooseberry Hill: Noel Hoffman. p. 419. ISBN 9780646562322.
  5. "Conservation Advice Pterostylis sinuata Northampton midget greenhood" (PDF). Australian Government Department of the Environment. Retrieved 17 July 2017.
  6. "Hymenochilus sinuatus". APNI. Retrieved 17 July 2017.
  7. Brown, Roland Wilbur (1956). The Composition of Scientific Words. Washington, D.C.: Smithsonian Institution Press. p. 140.
  8. "Pterostylis sinuata". FloraBase. Western Australian Government Department of Parks and Wildlife.
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