''Pterostylis riparia'', commonly known as the streamside greenhood, is a plant in the orchid family Orchidaceae and is endemic to New South Wales. Both flowering and non-flowering plants have a rosette of dark green, fleshy leaves. Flowering plants have a single, relatively large green, white and reddish-brown flower with a deeply notched sinus between hairy lateral sepals.

Description

''Pterostylis riparia'', 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. Plants have a rosette of three or four dark green, fleshy leaves, each leaf long and wide. Flowering plants have a single green, white and reddish-brown flower long and wide on a stalk high. 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 joined to form a hood called the "galea" over the column with the dorsal sepal and petals a similar length and ending in a sharp point. There is a wide gap between the galea and the lateral sepals which are hairy and have erect, narrow tips long. The sinus between the lateral sepals is flat and hairy with a deep notch in the centre. The labellum is long, about wide and dark brown, protruding slightly above the sinus. Flowering occurs in October and November.

Taxonomy and naming

''Pterostylis riparia'' was first formally described in 2006 by David Jones from a specimen collected near Omadale Brook in the

Barrington Tops National Park The Barrington Tops National Park is a protected national park located in the Hunter Valley in New South Wales, Australia. Gazetted in 1969, the park is situated between Scone, Singleton, Dungog, Gloucester and East Gresford. The park is part ...

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 ...

is derived from the Latin ''riparius'' meaning 'of stream banks'.

Distribution and habitat

The streamside greenhood grows on moist forest slopes and is restricted to the

Conservation status

This greenhood is listed as "vulnerable" under the Australian Government '' Environment Protection and Biodiversity Conservation Act 1999'' and the New South Wales Government '' Biodiversity Conservation Act 2016''.

References

{{Taxonbar, from=Q15491783

riparia ''Riparia'' is a genus of passerine birds in the swallow family Hirundinidae. These are small or medium-sized swallows, ranging from in length. They are brown above and mainly white below, and all have a dark breast band. They are closely ass ...

Endemic orchids of Australia Orchids of New South Wales Plants described in 2006