Pterostylis atrans

Pterostylis atrans, commonly known as the dark-tip greenhood[2] or blunt-tongue greenhood,[3] is a species of orchid endemic to south-eastern Australia. As with similar greenhoods, plants in flower differ from those that are not flowering. The non-flowering plants have a rosette of leaves flat on the ground, but the plants in flower have a single flower with leaves on the flowering spike. In this species, the flower is green and reddish brown with a protruding sinus and small club-like tips on the ends of the lateral sepals.

Dark-tip greenhood
Pterostylis atrans growing near Mount Toolebewong
Scientific classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Monocots
Order: Asparagales
Family: Orchidaceae
Subfamily: Orchidoideae
Tribe: Cranichideae
Genus: Pterostylis
Species:
P. atrans
Binomial name
Pterostylis atrans
Synonyms[1]

Diplodium atrans (D.L.Jones) D.L.Jones & M.A.Clem.

Description

Pterostylis atrans is a terrestrial, perennial, deciduous, herb with an underground tuber and when not flowering, a rosette of egg-shaped leaves, each leaf 10–35 mm long and 10–30 mm wide. Flowering plants have a single flower 14–20 mm long and 10–12 mm wide borne on a spike 150–300 mm high with between three and five spreading stem leaves. The flowers are green with a reddish-brown, down curved tip. The dorsal sepal and petals are fused, forming a hood or "galea" over the column and the dorsal sepal has a thread-like tip 6–9 mm long. The lateral sepals are held closely against the galea, have erect, thread-like tips 15–20 mm long with small club-like tips and a protruding, platform-like sinus between their bases. The labellum is 9–11 mm long, about 3 mm wide, green with a blunt brown tip that is just visible above the sinus. Flowering occurs from November to April.[2][3][4]

Taxonomy and naming

Pterostylis atrans was first formally described in 1994 by David Jones from a specimen collected in the Brindabella Range. The description was published in Muelleria.[1][4] The specific epithet is "from the Latin word atrans, darkening, in reference to the dark red-brown colouration towards the apex of the galea".[2]

Distribution and habitat

The dark-tip greenhood mostly grows among grasses in high rainfall forests in Victoria, Tasmania and southern New South Wales.[2][3][5]

References
  1. "Pterostylis atrans". APNI. Retrieved 3 May 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. p. 288. ISBN 978-1877069123.
  3. Jeanes, Jeff. "Pterostylis atrans". Royal Botanic Gardens Victoria: vicflora. Retrieved 3 May 2017.
  4. Jones, David L. (1994). "A new species of Orchidaceae from Victoria" (PDF). Muelleria. 8 (2): 185–186. Retrieved 3 May 2017.
  5. Jones, David L. (1998). "Contributions to Tasmanian Orchidology - 7". Australia Orchid Research. 3: 139–140.
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