Pterostylis revoluta

Autumn greenhood
Pterostylis revoluta growing in the Aranda bushland reserve
Scientific classification
Kingdom: Plantae
(unranked): Angiosperms
(unranked): Monocots
Order: Asparagales
Family: Orchidaceae
Genus: Pterostylis
Species: P. revoluta
Binomial name
Pterostylis revoluta
R.Br.[1]
Synonyms[1]

Pterostylis revoluta, commonly known as the autumn greenhood, is a species of orchid endemic to south-eastern Australia. As with similar greenhoods, the flowering plants differ from those which are not flowering. The non-flowering plants have a rosette of leaves flat on the ground but the flowering plants have a single flower with leaves on the flowering spike. This greenhood has white and green flowers which have a long, curved, pointed labellum which extends beyond the sinus between the lateral sepals.

Description

Pterostylis revoluta is a terrestrial, perennial, deciduous, herb with an underground tuber and when not flowering, a rosette of between three and seven greyish to bluish, egg-shaped leaves. Each leaf in the rosette is 10-30 mm long and 4-12 mm wide. Flowering plants have a single flower 20-25 mm long, 9-12 mm wide and which lean forwards slightly. The flower is borne on a flowering stem 100-150 mm high with between three and five leaves wrapped around the stem. The flowers are pale green and white with a brown tinge. The dorsal sepal and petals are fused, forming a hood or "galea" over the column. The dorsal sepal curves forward and downward with a thread-like tip 4-8 mm long. The lateral sepals are held closely against the galea, have an erect, curved thread-like tip 20-25 mm long and a narrow V-shaped sinus between their bases. The labellum is 14-17 mm long, about 3 mm wide, curved, pointed and extends for about half its length above the sinus. Flowering occurs from February to June.[2][3]

Taxonomy and naming

Pterostylis revoluta was first formally described in 1810 by Robert Brown and the description was published in the Prodromus Florae Novae Hollandiae et Insulae Van Diemen.[1][4] The specific epithet (revoluta) is a Latin word meaning "turned over" or "rolled back".[5]

Distribution and habitat

The autumn greenhood grows on sheltered slopes in forest and in coastal scrub in coastal and near-coastal area from south-east Queensland to Nowra in New South Wales and as far inland as Cessnock.[2][3]

References

  1. 1 2 3 "Pterostylis pedunculata". APNI. Retrieved 24 May 2017.
  2. 1 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. 296. ISBN 1877069124.
  3. 1 2 Jones, David L. "Pterostylis revoluta". Royal Botanic Garden Sydney: plantnet. Retrieved 24 May 2017.
  4. ↑ Brown, Robert (1810). Prodromus Florae Novae Hollandiae et Insulae Van Diemen. London. p. 327. Retrieved 22 May 2017.
  5. ↑ Brown, Roland Wilbur (1956). The Composition of Scientific Words. Washington, D.C.: Smithsonian Institution Press. p. 657.
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