''Pterostylis psammophila'', commonly known as the two-bristle greenhood, is a plant in the orchid family Orchidaceae and is endemic to South Australia. Both flowering and non-flowering plants have a rosette of leaves and flowering plants have translucent green and white flowers with an insect-like labellum, but the flowers are only open for a few days.

Description

''Pterostylis psammophila'' 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 and a rosette of between six and sixteen overlapping leaves. The leaves are up to leaves are up to long and have a serrated edge. Flowering plants have a rosette at the base of the flowering stem but the leaves are usually withered by flowering time. The flowers are green or translucent white but are short-lived and borne on a flowering stem usually about 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 form a hood or "galea" over the column, the lateral sepals turn downwards and the labellum is insect-like with two long bristles on the "head" end. Flowering occurs between late August and October.

Taxonomy and naming

The two-bristle greenhood was first formally described in 2007 by

D.L.Jones David Lloyd Jones (born 1944) is an Australian horticultural botanist and the author of many books and papers, especially on Australian orchids. Jones was born in Victoria and in his youth was a student at Burnley Horticultural College, then th ...

who gave it the name ''Oligochaeochilus psammophilus''. The description was published in ''The Orchadian'' from a specimen collected near

Cockatoo Valley Cockatoo Valley is a locality in the Australian state of South Australia located about north-east of the state capital of Adelaide and about south-west of the municipal seat of Nuriootpa. It was first seen and named by Europeans on 3 March ...

. In 2008, Robert Bates changed the name to ''Pterostylis psammophila''. 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 ...

(''psammophila'') is derived from the Ancient Greek ''ψάμμος (psámmos)'', meaning “sand” and ''φίλος (phílos)'', meaning “dear one" or "friend”.

Distribution

''Pterostylis psammophila'' is only known from two populations near Lyndoch.

Conservation

''Pterostylis psammophila'' is classified as "critically endangered" Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act). The species is threatened by illegal collection, weed invasion and grazing by livestock and rabbits.

References

{{Taxonbar, from=Q15494466 psammophila Endemic orchids of Australia Orchids of South Australia Plants described in 2007