Pterostylis russellii

Pterostylis russellii, commonly known as Russell's greenhood, is a species of orchid endemic to eastern Australia. Non-flowering plants have a rosette of leaves flat on the ground but flowering plants have a single shiny white and dark green flower on a flowering stem lacking a rosette but with a few spreading stem leaves.

Russell's greenhood
Pterostylis russellii near Nowendoc
Scientific classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Monocots
Order: Asparagales
Family: Orchidaceae
Subfamily: Orchidoideae
Tribe: Cranichideae
Genus: Pterostylis
Species:
P. russellii
Binomial name
Pterostylis russellii
T.E.Hunt[1]
Synonyms[2]

Diplodium russellii (T.E.Hunt) (D.L.Jones) & M.A.Clem.

Habit

Description

Pterostylis russellii is a terrestrial, perennial, deciduous, herb with an underground tuber and when not flowering, a rosette of between three and six dark green, oblong to heart-shaped leaves, each leaf 15–40 mm (0.6–2 in) long and 10–18 mm (0.4–0.7 in) wide. Flowering plants have a single shiny dark green and white flower 15–20 mm (0.6–0.8 in) long and 7–9 mm (0.3–0.4 in) wide on a stem 200–350 mm (8–10 in) tall with three to five stem leaves. The dorsal sepal and petals are fused, forming a hood or "galea" over the column curving forward in a semi-circle. The dorsal sepal ends with a thread-like tip 3–7 mm (0.1–0.3 in) long. The lateral sepals are held closely against the galea, have erect thread-like tips 20–30 mm (0.8–1 in) long and a protruding, V-shaped sinus between their bases. The labellum is about 11–14 mm (0.4–0.6 in) long and about 3 mm (0.1 in) wide, blackish, blunt and protruding above the sinus. Flowering occurs from April to August.[3][4]

Taxonomy and naming

Pterostylis russellii was first formally described in 1952 by Trevor Hunt from a specimen collected near Brisbane and the description was published in The Orchid Journal (California).[1] The specific epithet (russellii) honours "Mr. A.J. Russell, then Captain Russell, a keen and competent student of Australian orchids" who first collected this species.[5]

Distribution and habitat

Russell's greenhood grows in moist, shady places in forest between Grafton in New South Wales and Gympie in Queensland.[3][4]

References
  1. "Pterostylis russellii". APNI. Retrieved 16 July 2017.
  2. "Pterostylis russellii". World Checklist of Selected Plant Families (WCSP). Royal Botanic Gardens, Kew.
  3. Jones, David L. (2006). A complete guide to native orchids of Australia including the island territories. Frenchs Forest, N.S.W.: New Holland. pp. 289–290. ISBN 978-1877069123.
  4. "Pterostylis russellii". Royal Botanic Garden Sydney. Retrieved 16 July 2017.
  5. Hunt, Trevor E. (1952). "A new species of Pterostylis from south Queensland". The Orchid Journal: An International Review of Orchidology. 1: 42.
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