Pterostylis ventricosa

Pterostylis ventricosa is a recently described and critically endangered species of orchid endemic to a small area of New South Wales. As with similar orchids, the flowering plants differ from those which are not flowering. The non-flowering plants have a rosette of leaves but the flowering plants lack a rosette at the base but have up to six tiny green, white and brown flowers.

Pterostylis ventricosa
Pterostylis ventricosa growing near Jervis Bay
Scientific classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Monocots
Order: Asparagales
Family: Orchidaceae
Subfamily: Orchidoideae
Tribe: Cranichideae
Genus: Pterostylis
Species:
P. ventricosa
Binomial name
Pterostylis ventricosa
(D.L.Jones) G.N.Backh.[1]
Synonyms[2]

Speculantha ventricosa D.L.Jones

Description

Pterostylis ventricosa is a terrestrial, perennial, deciduous, herb with an underground tuber and when not flowering, a rosette of four to nine dark green, egg-shaped leaves which lie flat on the ground. Each leaf is 3–12 mm (0.1–0.5 in) long and 3–6 mm (0.1–0.2 in) wide. Flowering plants have up to six well-spaced flowers 10–13 mm (0.4–0.5 in) long and about 5 mm (0.2 in) wide borne on a thin, wiry spike 80–300 mm (3–10 in) high. One or two leaf rosettes are arranged on the side of the flowering spike. The flowers are green and white, swollen at the base and taper towards a bright reddish-brown tip. The dorsal sepal and petals are fused, forming a hood or "galea" over the column. The dorsal sepal is erect near the base but then curves forward and is 13–16 mm (0.5–0.6 in) long and 5–8 mm (0.2–0.3 in) wide. The petals are slightly longer than the dorsal sepal. The lateral sepals are erect, held closely against the galea with thread-like tips about 3mm long reaching just past the top of the galea. The labellum is about 5 mm (0.2 in) long, 2 mm (0.08 in) wide, dark brown and white, curved and barely visible above the sinus.[3][4]

Taxonomy and naming

This greenhood was first formally described in 2008 by D.L.Jones who gave it the name Speculantha ventricosa and published the description in The Orchadian.[5] In 2010, Gary Backhouse changed the name to Pterostylis ventricosa.[1] The specific epithet (ventricosa) is a Latin word meaning "pot-bellied" or "bulging".[6]

Distribution and habitat

The tiny greenhood mostly grows in tall forest with a dense understorey, but sometimes in disturbed areas, including roadsides. It occurs near Nowra, Tallong and Mittagong.[3][4]

Conservation

Pterostylis ventricosa is classed as "critically endangered" under the New South Wales Threatened Species Conservation Act. The main threats to the species are land clearing, disturbance by off-road vehicles, grazing by livestock and illegal collection.[3][4]

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References
  1. "Pterostylis ventricosa". APNI. Retrieved 31 May 2017.
  2. "Pterostylis ventricosa". World Checklist of Selected Plant Families (WCSP). Royal Botanic Gardens, Kew.
  3. "Pterostylis ventricosa an orchid - critically endangered species listing". Government of New South Wales, Office of the Environment and Heritage. Retrieved 31 May 2017.
  4. "Pterostylis ventricosa - profile". Government of New South Wales, Office of the Environment and Heritage. Retrieved 31 May 2017.
  5. "Speculantha ventricosa". APNI. Retrieved 31 May 2017.
  6. Brown, Roland Wilbur (1956). The Composition of Scientific Words. Washington, D.C.: Smithsonian Institution Press. p. 137.
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