Pterostylis depauperata

Pterostylis depauperata, commonly known as the keeled greenhood, is a species of orchid endemic to Queensland. Flowering plants have a rosette of leaves at the base of a flowering stem with a single small white flower with pale green marks, and a few small stem leaves. Non-flowering plants only have a rosette of leaves. All three sepals on the flower have relatively long, thread-like tips.

Keeled greenhood
Drawing of Pterostylis depauperata by Lewis Roberts
Scientific classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Monocots
Order: Asparagales
Family: Orchidaceae
Subfamily: Orchidoideae
Tribe: Cranichideae
Genus: Pterostylis
Species:
P. depauperata
Binomial name
Pterostylis depauperata
Synonyms

Description

Pterostylis depauperata is a terrestrial, perennial, deciduous, herb with an underground tuber and which often grows in colonies. Non-flowering plants have a rosette of between three and seven egg-shaped, greyish green leaves lying flat on the ground. Each leaf is 10–40 mm (0.4–2 in) long and 5–10 mm (0.2–0.4 in) wide. Flowering plants have a single flower 15–17 mm (0.6–0.7 in) long and 8–10 mm (0.3–0.4 in) wide on a flowering stem 80–200 mm (3–8 in) high with a few small stem leaves. The flowers are white with pale green striations. The dorsal sepal and petals are fused, forming a hood or "galea" over the column. The dorsal sepal has a thread-like tip 10–13 mm (0.4–0.5 in) long and lateral sepals are erect, held closely against the galea and have thread-like tips 17–20 mm (0.7–0.8 in) long. The labellum is 8–10 mm (0.3–0.4 in) long, about 3 mm (0.1 in) wide, dark brown and curved, and just protrudes above the sinus. Flowering occurs from March to August.[2][3]

Taxonomy and naming

Pterostylis depauperata was first formally described in 1943 by Frederick Bailey from a specimen collected near Cairns. The description was published in the Botany Bulletin of the Queensland Department of Agriculture.[1]

Distribution and habitat

The keeled greenhood grows with grasses and small shrubs in woodland and forest between Cooktown and Ravenshoe at altitudes above 500 m (1,600 ft).[2][3]

References
  1. "Pterostylis depauperata". APNI. Retrieved 25 June 2017.
  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. 286–287. ISBN 978-1877069123.
  3. "Crangonorchis depauperata". Lucid Key Server. Retrieved 25 June 2017.
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