Pterostylis bicolor

Pterostylis bicolor, commonly known as the black-tip greenhood, is a plant in the orchid family Orchidaceae and is endemic to south-eastern Australia. It has a rosette of leaves and when flowering, three to ten well-spaced, bright green flowers with a blunt, greenish-black appendage on the labellum. It is similar to the swan orchid, Pterostylis cycnocephala but that species has a beak-like appendage and crowded flowers.

Black-tip greenhood
Scientific classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Monocots
Order: Asparagales
Family: Orchidaceae
Subfamily: Orchidoideae
Tribe: Cranichideae
Genus: Pterostylis
Species:
P. bicolor
Binomial name
Pterostylis bicolor
Synonyms[1]
  • Pterostylis bicolor R.Br.
  • Oligochaetochilus bicolor (D.L.Jones & M.A.Clem.) Szlach.
  • Hymenochilus bicolor (D.L.Jones & M.A.Clem.) D.L.Jones & M.A.Clem.

Description

Pterostylis bicolor, is a terrestrial, perennial, deciduous, herb with an underground tuber. It has a rosette of between five and twelve dark green leaves, each leaf 10–35 mm (0.4–1 in) long and 3–15 mm (0.1–0.6 in) wide. When flowering there are between three and ten well-spaced, bright shiny green flowers 8–11 mm (0.3–0.4 in) long and 4–5 mm (0.2–0.2 in) wide on a flowering spike 80–300 mm (3–10 in) tall. Six to eleven stem leaves are wrapped around the flowering spike. The dorsal sepal and petals form a hood or "galea" over the column. The lateral sepals turn downwards, 6–7 mm (0.2–0.3 in) long and 7–8 mm (0.28–0.31 in) wide, dished and joined for most of their length. The labellum is egg-shaped, 3 mm (0.1 in) long and 2 mm (0.08 in) wide, with a greenish-black, blunt, ridged, forward pointing appendage. Flowering occurs from August to November.[2][3][4]

Taxonomy and naming

Pterostylis bicolor was first formally described in 1987 by David Jones & Mark Clements and the description was published in Proceedings of the Royal Society of Queensland.[1] The specific epithet (bicolor) is a Latin word meaning "two-coloured".[5]

Distribution and habitat

The black-tip greenhood is widespread in New South Wales and found in scattered populations in Victoria. It grows in grassy woodland and forest.[2][3][4]

References
  1. "Pterostylis bicolor". APNI. Retrieved 27 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. 320. ISBN 978-1877069123.
  3. Jones, David L. "Pterostylis bicolor". Royal Botanic Garden Sydney: plantnet. Retrieved 27 May 2017.
  4. Jeanes, Jeff. "Pterostylis bicolor". Royal Botanic Gardens Victoria: vicflora. Retrieved 27 May 2017.
  5. Brown, Roland Wilbur (1956). The Composition of Scientific Words. Washington, D.C.: Smithsonian Institution Press. p. 28.
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