Pterostylis truncata

Pterostylis truncata, commonly known as the brittle greenhood or little dumpies,[2] is a species of orchid endemic to eastern Australia. It is easily distinguished from other greenhood orchids by its short habit and relatively large, "dumpy", green, white and brown flowers. It is widespread and common in New South Wales and the Australian Capital Territory but is classed as "endangered" in Victoria due to habitat loss as a result of urbanisation.

Brittle greenhood
Pterostylis truncata growing near Armidale
Scientific classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Monocots
Order: Asparagales
Family: Orchidaceae
Subfamily: Orchidoideae
Tribe: Cranichideae
Genus: Pterostylis
Species:
P. truncata
Binomial name
Pterostylis truncata
Synonyms[1]

Diplodium truncatum (Fitzg.) D.L.Jones & M.A.Clem.

Description

When not flowering, Pterostylis truncata has a rosette of between two and six bright green, egg-shaped to lance-shaped leaves, each leaf 10–35 mm (0.4–1 in) long and 5–18 mm (0.2–0.7 in) wide. When it flowers it produces a single white flower with green and brown stripes, borne on a spike 50–150 mm (2–6 in) high. There are between two and five stem leaves closely wrapped around the flowering spike. The flowers are 35–45 mm (1–2 in) long, 7–20 mm (0.3–0.8 in) wide and inflated, leaning forward with a downturned tip. The dorsal sepal has a sharp point and the petals turn inwards underneath it. The lateral sepals have a deep V-shaped sinus between them and each sepal has a thread-like tip 25–30 mm (0.98–1.2 in) long.[3][2][4][5][6]

Pterostylis truncata leaf rosette

Taxonomy and naming

Pterostylis truncata was first described in 1878 by Robert FitzGerald from a specimen collected near Mittagong and the description was published in Fitzgerald's book Australian Orchids.[1] The specific epithet (truncata) is a Latin word meaning "to maim or shorten by cutting off".[7]

Distribution and habitat

The brittle greenhood is widespread and common in New South Wales, and the Australian Capital Territory where it grows in forest, often on sheltered ridges and slopes south from the New England Tableland. It is rare in Victoria where it grows in well-drained soil in grassland, woodland or on granite outcrops within 100 km (60 mi) of Melbourne.[3][2][5]

Conservation

Pterostylis truncata is classed as "endangered" under the Victorian Government Flora and Fauna Guarantee Act 1988. Populations are only known from the You Yangs, Black Hill Reserve near Ballarat and the Long Forest Nature Conservation Reserve near Bacchus Marsh although the range of the orchid was once considerably larger. The main threats to the species and factors in its decline in Victoria, include grazing by European rabbits (Oryctolagus cuniculus), feral goats (Capra hircus) and eastern grey kangaroos (Macropus giganteus), as well as weed invasion, especially boneseed (Chrysanthemoides monilifera) and habitat loss due to urbanisation.[5][8][9]

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References
  1. "Pterostylis truncata". APNI. Retrieved 26 April 2017.
  2. Jones, David L. "Pterostylis truncata". Royal Botanic Garden Sydney: plantnet. Retrieved 26 April 2017.
  3. Jones, David L. (2006). A complete guide to native orchids of Australia including the island territories. Frenchs Forest, N.S.W.: New Holland. p. 297. ISBN 978-1877069123.
  4. G.R. Coachrane, B.A. Fuhrer, E.R. Rotherham (chairman), J.H. Willis (1968). Australian Flora in Colour: Flowers and Plants of Victoria. Kyodo Printing Co. Tokyo: A.H. & A.W. Reed Company. pp. 75 Figure 203.CS1 maint: multiple names: authors list (link)
  5. Jeanes, Jeff. "Pterostylis truncata". Royal Botanic Gardens Victoria: vicflora. Retrieved 26 April 2017.
  6. "Fauna and flora guarantee: action statement: Brittle greenhood Pterostylis truncata" (PDF). The State of Victoria, Department of Sustainability and Environment, 2003. Retrieved 26 January 2015.
  7. Brown, Roland Wilbur (1956). The Composition of Scientific Words. Washington, D.C.: Smithsonian Institution Press. p. 708.
  8. "Fauna and Flora Guarantee Action Statement - Pterostylis truncata" (PDF). Government of Victoria, Department of Sustainability and the Environment. Retrieved 26 April 2017.
  9. "Weeds of National Significance - Boneseed (Chrysanthemoides monilifera ssp. monilifera)" (PDF). Australian Government Department of the Environment. Retrieved 26 April 2017.
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