''Pterostylis tunstallii'', commonly known as Tunstall's greenhood or granite 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 ...

. Flowering plants have up to ten transparent green flowers which have a dark brown, insect-like labellum with a blackish "head". Non-flowering plants have a rosette of leaves on a short stalk but flowering plants lack the rosette, instead having five to eight stem leaves.

Description

''Pterostylis tunstallii'', 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. Non-flowering plants have a rosette of between three and five egg-shaped leaves on a stalk long, each leaf long and wide. Flowering plants have up to ten transparent green flowers on a flowering spike high. The flowering spike has between five and eight stem leaves which are long and wide. The flowers are long, wide. 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 are fused, forming a hood or "galea" over the

column A column or pillar in architecture and structural engineering is a structural element that transmits, through compression, the weight of the structure above to other structural elements below. In other words, a column is a compression member. ...

with the dorsal sepal having a short point on its tip. The lateral sepals turn downwards, are long, wide, joined for most of their length and have a narrow tip about long which is brown on its end. The labellum is insect-like, about long, wide and dark brown with a blackish "head" end. Flowering occurs from July to August.

Taxonomy and naming

''Pterostylis tunstallii'' was first formally described in 1989 by David Jones and Mark Clements and the description was published in ''Australian Orchid Research''. 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 ...

(''tunstallii'') honours Ronald George Tunstall who collected the type specimen.

Distribution and habitat

Tunstall's greenhood occurs south from Blue Mountains in New South Wales, in southern Victoria east from Wilsons Promontory and in Tasmania including the

Bass Strait islands Bass Strait () is a strait separating the island state of Tasmania from the Australian mainland (more specifically the coast of Victoria, with the exception of the land border across Boundary Islet). The strait provides the most direct waterway ...

. It grows in moist forest in coastal and near-coastal districts.

References

{{Taxonbar, from=Q15491877 tunstallii Endemic orchids of Australia Orchids of New South Wales Orchids of Victoria (Australia) Orchids of Tasmania Plants described in 1989