''Pterostylis nana'', commonly known as the dwarf snail orchid, is a species of orchid endemic to

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 at it base and a single narrow, bright green and white flower with a small labellum. There is uncertainty about its classification - some sources include South Australia and Western Australia in its range.

Description

''Pterostylis nana'' 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 egg-shaped to heart-shaped leaves, each leaf 5–20 mm long and 3–10 mm wide. A single bright green and white flower, 10–15 mm long and 4–5 mm wide is borne on a stalk 50–150 mm high. The dorsal sepal is erect, more or less flat on top and fused to the

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 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 lateral sepals are erect, in close contact with the galea and taper to a thread-like tip about 20 mm long. The sinus between the lateral sepals is more or less flat and has a dark green central area. The labellum is 3–5 mm long, about 2 mm wide, straight, blunt and hidden inside the flower. Flowering occurs from July to October. The State Herbarium of South Australia lists this species as being present in that state and in Western Australia. The Royal Botanic Garden Melbourne reports that the taxonomy of the species is "under investigation".

Taxonomy and naming

''Pterostylis nana'' was first formally described in 1985 by Robert Brown and the description was published in '' Prodromus Florae Novae Hollandiae et Insulae Van Diemen''.

Distribution and habitat

The dwarf snail orchid grows in a range of habitats from coastal heath to forest, mostly in sheltered sites. It occurs in New South Wales south from Taree and is widespread in Victoria and Tasmania

References

{{Taxonbar, from=Q15498726 nana Endemic orchids of Australia Orchids of New South Wales Orchids of Tasmania Orchids of Victoria (Australia) Plants described in 1810