''Pterostylis erythroconcha'', commonly known as the red shell orchid, is a species of orchid endemic to South Australia. As with similar orchids, the flowering plants differ from those which are not flowering. The non-flowering plants have a rosette of leaves but the flowering plants have a single flower with leaves on the flowering spike. This greenhood has a white and green flower with reddish brown markings and a long, fleshy, curved labellum.

Description

''Pterostylis erythroconcha'' 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 when not flowering, a rosette of between three and ten egg-shaped leaves. Each leaf is long and wide. Flowering plants have a single flower long and wide borne on a flowering stem high. The flowers are translucent white with reddish-brown stripes and markings. 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. ...

. The dorsal sepal curves forward with sharp point or a thread-like tip long. The lateral sepals are held closely against the galea, have an erect, thread-like tip long and a broad, flat sinus with a small notch between their bases. The labellum is long, about wide, thick, fleshy and reddish-brown protruding prominently above the sinus. Flowering occurs from April to August.

Taxonomy and naming

''Pterostylis erythroconcha'' was first formally described in 1985 by Mark Clements and David Jones from a specimen collected near Corny Point. The description was published in the fourth edition of ''Flora of South Australia''. 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 ...

(''erythroconcha'') is derived from the Ancient Greek words ''erythros'' meaning "red" and ''konche'' meaning "snail".

Distribution and habitat

The red shell orchid grows on calcareous sand and limestone, sometimes forming large colonies, usually near the coast, in mallee. It is found in the south-east of South Australia.

References

{{Taxonbar, from=Q15491485 erythroconcha Endemic orchids of Australia Orchids of South Australia Plants described in 1986