''Pterostylis decurva'', commonly known as the summer greenhood, is a species of
orchid 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 ...
. As with similar greenhoods, 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 usually flowers in summer and has a white flower with green stripes and a brownish tinge. It is similar to
''P. aestiva'' but has paler green flowers.
Description
''Pterostylis decurva'' 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 two to five leaves often held above the ground on a stalk up to 100 mm long. Each leaf is oblong to egg-shaped, 10–30 mm long and 10–20 mm wide. Flowering plants have a single flower 18–25 mm long and 7–9 mm wide borne on a spike 150–300 mm high with four or five stem leaves. The flowers are white with green stripes and a brown tinge in the galea. 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, often downwards, with a thread-like tip 15–20 mm long. The
lateral sepals are held closely against the galea, have an erect, thread-like tip 30–40 mm long and a broad, slightly protruding, U-shaped
sinus between their bases. The labellum is 12–15 mm long, 2.5 mm wide, brown, blunt, and curved and protrudes above the sinus. Flowering occurs from October to March.
Taxonomy and naming
''Pterostylis decurva'' was first formally described in 1923 by
Richard Sanders Rogers and the description was published in ''
''.
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 ...
(''decurva'') is a
Latin word meaning "curved or bent downwards".
Distribution and habitat
The summer greenhood grows on the higher parts of the ranges and tablelands of
Victoria,
New South Wales south from
Werrikimbe National Park and
Tasmania where it sometimes also grows at lower altitudes.
References
{{Taxonbar, from=Q15499395
decurva
Endemic orchids of Australia
Orchids of New South Wales
Orchids of Tasmania
Orchids of Victoria (Australia)
Plants described in 1923