Pterostylis cycnocephala

Pterostylis cycnocephala, commonly known as the swan greenhood, is a plant in the orchid family Orchidaceae and is endemic to south-eastern Australia. It has a rosette of leaves and up to 24 green flowers which have a labellum with a dark green, beak-like appendage. It is widespread and common from the Darling Downs in Queensland to Tasmania, usually growing with grasses.

Labelled image of P. cycnocephala
Whole plant of P. cycnocephala

Swan greenhood
Scientific classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Monocots
Order: Asparagales
Family: Orchidaceae
Subfamily: Orchidoideae
Tribe: Cranichideae
Genus: Pterostylis
Species:
P. cycnocephala
Binomial name
Pterostylis cycnocephala
Synonyms[1]

Description

Pterostylis cycnocephala, is a terrestrial, perennial, deciduous, herb with an underground tuber. It has a rosette of between six and twelve dark green leaves at the base of the flowering spike, each leaf 12–35 mm (0.5–1 in) long and 8–15 mm (0.3–0.6 in) wide. Up to 24 shiny green flowers 7–9 mm (0.3–0.4 in) long and about 4 mm (0.2 in) wide are borne on a flowering spike 80–300 mm (3–10 in) tall. Three to six stem leaves are wrapped around the flowering spike. The dorsal sepal and petals form a hood or "galea" over the column. The dorsal sepal is blunt and curved downwards with the sides turned down. The lateral sepals turn downwards, about 6 mm (0.2 in) long and 5 mm (0.2 in) wide, dished and joined for most of their length. The labellum is rectangular in shape, about 2 mm (0.08 in) long and whitish-green with a dark green, beak-like appendage pointing forward at its base. Flowering occurs from August to December.[2][3][4][5]

Taxonomy and naming

Pterostylis cycnocephala was first formally described in 1936 by Robert FitzGerald and the description was published in Fitzgerald's book, Australian Orchids.[1] The specific epithet (cycnocephala) is derived from the Ancient Greek words kyknos meaning "swan"[6]:373 and kephale meaning "head",[6]:399 referring to the labellum appendage having the shape of a swan's head and neck.[1]

Distribution and habitat

The swan greenhood is common and widespread from the Darling Downs in Queensland, through New South Wales and Victoria to Tasmania, growing mostly in grassy places.[2][3][4][5]

References
  1. "Pterostylis cycnocephala". APNI. Retrieved 11 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 cycnocephala". Royal Botanic Garden Sydney: plantnet. Retrieved 11 May 2017.
  4. Jeanes, Jeff. "Pterostylis cycnocephala". Royal Botanic Gardens Victoria: vicflora. Retrieved 11 May 2017.
  5. "Pterostylis cycnocephala". State Herbarium of South Australia: efloraSA. Retrieved 11 May 2017.
  6. Brown, Roland Wilbur (1956). The Composition of Scientific Words. Washington, D.C.: Smithsonian Institution Press.
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