''Pterostylis cycnocephala'', commonly known as the swan greenhood, is a plant in the orchid family Orchidaceae and is endemic to south-eastern

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

. It has a rosette of leaves and up to 24 green flowers which have a labellum with a dark green, beak-like

appendage An appendage (or outgrowth) is an external body part, or natural prolongation, that protrudes from an organism's body. In arthropods, an appendage refers to any of the homologous body parts that may extend from a body segment, including anten ...

. It is widespread and common from the Darling Downs in Queensland to Tasmania, usually growing with grasses.

Description

''Pterostylis cycnocephala'', is a terrestrial, perennial, deciduous,

herb In general use, herbs are a widely distributed and widespread group of plants, excluding vegetables and other plants consumed for macronutrients, with savory or aromatic properties that are used for flavoring and garnishing food, for medicinal ...

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 long and wide. Up to 24 shiny green flowers long and about wide are borne on a flowering spike tall. Three to six stem leaves are wrapped around the flowering spike. The dorsal sepal and

petal Petals are modified Leaf, leaves that surround the reproductive parts of flowers. They are often advertising coloration, brightly colored or unusually shaped to attract pollinators. All of the petals of a flower are collectively known as the ''c ...

s 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 long and wide, dished and joined for most of their length. The labellum is rectangular in shape, about long and whitish-green with a dark green, beak-like appendage pointing forward at its base. Flowering occurs from August to December.

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''. The

specific epithet In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...

(''cycnocephala'') is derived from the Ancient Greek words ''kyknos'' meaning "swan" and ''kephale'' meaning "head", referring to the labellum appendage having the shape of a swan's head and neck.

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.

References

{{Taxonbar, from=Q15496697 cycnocephala Endemic orchids of Australia Orchids of New South Wales Orchids of Queensland Orchids of Tasmania Orchids of Victoria (Australia) Plants described in 1876