Pterostylis robusta

Sharp-leaf greenhood
Pterostylis robusta growing near Charlton
Scientific classification
Kingdom: Plantae
(unranked): Angiosperms
(unranked): Monocots
Order: Asparagales
Family: Orchidaceae
Genus: Pterostylis
Species: P. robusta
Binomial name
Pterostylis robusta
R.S.Rogers[1]
Synonyms[2]

  • Pterostylis scabra var. robusta (R.S.Rogers) A.S.George
  • Pterostylis alata var. robusta (R.S.Rogers) J.Z.Weber & R.J.Bates
  • 'Diplodium robustum (R.S.Rogers) D.L.Jones & M.A.Clem.

Pterostylis robusta, commonly known as the sharp-leaf greenhood, is a species of orchid endemic to south-eastern Australia. 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 have a single flower with leaves on the flowering spike. This greenhood has a relatively large green, white and reddish-brown flower with reddish-brown stripes with the labellum just visible inside the flower.

Description

Pterostylis robusta is a terrestrial, perennial, deciduous, herb with an underground tuber and when not flowering, a rosette of four to ten, dark green, egg-shaped leaves. Each leaf is 10–25 mm long and 10–16 mm wide. Flowering plants have a single flower 27–35 mm long and 10–12 mm wide borne on a spike 50–200 mm high with three to seven spreading stem leaves. The flowers are green, white and brownish with a reddish-brown tinge or stripes. The dorsal sepal and petals are fused, forming a hood or "galea" over the column. The dorsal sepal curves forward with a sharp point 2–4 mm long. The lateral sepals are erect, held closely against the galea, have an erect, thread-like tip 20–30 mm long and a flat sinus with a small notch between their bases. The labellum is 12–15 mm long, 3–4 mm wide, dark brown or green and just visible inside the flower. Flowering occurs from April to August.[3][4][5][6]

Taxonomy and naming

Pterostylis robusta was first formally described in 1927 by Richard Sanders Rogers and the description was published Transactions and proceedings of the Royal Society of South Australia.[1][7] The specific epithet (robusta) is a Latin word meaning strong like oak or "robust".[8]

Distribution and habitat

The sharp-leaf greenhood is most common in the higher rainfall areas of South Australia where it sometimes forms externsive colonies. In Victoria it grows in open forest in the north-west of the state but it is rare in New South Wales where it grows on sheltered ridges south from Wagga Wagga.[3][4][5][6]

References

  1. 1 2 "Pterostylis robusta". APNI. Retrieved 25 May 2017.
  2. ↑ "Pterostylis robusta". World Checklist of Selected Plant Families (WCSP). Royal Botanic Gardens, Kew.
  3. 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. pp. 292–293. ISBN 1877069124.
  4. 1 2 Jeanes, Jeff. "Pterostylis robusta". Royal Botanic Gardens Victoria: vicflora. Retrieved 25 May 2017.
  5. 1 2 Jones, David L. "Pterostylis robusta". Royal Botanic Garden Sydney: plantnet. Retrieved 25 May 2017.
  6. 1 2 "Pterostylis robusta". State Herbarium of South Australia: eflora SA. Retrieved 25 May 2017.
  7. ↑ Rogers, Richard Sanders (1927). "Contribution to the Orchidology of Australia". Transactions and proceedings of the Transactions and Proceedings of the Royal Society of South Australia. 51: 296–297. Retrieved 25 May 2017.
  8. ↑ Brown, Roland Wilbur (1956). The Composition of Scientific Words. Washington, D.C.: Smithsonian Institution Press. p. 556.
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