''Pterostylis robusta'', commonly known as the sharp-leaf 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 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 relatively large green, white and reddish-brown flower with reddish-brown stripes with the
labellum just visible inside the flower.
Description
''Pterostylis robusta'' 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 four to ten, dark green, egg-shaped leaves. Each leaf is 10–25 mm long and 10–16 mm wide. Flowering plants have a single flower 27–35 mm long and 10–12 mm wide borne on a spike 50–200 mm high with three to seven spreading stem leaves. The flowers are green, white and brownish with a reddish-brown tinge or stripes. 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 a sharp point 2–4 mm long. The
lateral sepals are erect, held closely against the galea, have an erect, thread-like tip 20–30 mm long and a flat
sinus with a small notch between their bases. The labellum is 12–15 mm long, 3–4 mm wide, dark brown or green and just visible inside the flower. Flowering occurs from April to August.
Taxonomy and naming
''Pterostylis robusta'' was first formally described in 1927 by
Richard Sanders Rogers and the description was published ''
''.
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 ...
(''robusta'') is a
Latin word meaning "strong like oak" or "robust".
Distribution and habitat
The sharp-leaf greenhood is most common in the higher rainfall areas of
South Australia where it sometimes forms extensive colonies. In
Victoria it grows in open forest in the north-west of the state but it is rare in
New South Wales where it grows on sheltered ridges south from
Wagga Wagga.
References
{{Taxonbar, from=Q15491928
robusta
ROBUSTA (Radiation on Bipolar for University Satellite Test Application) is a nano-satellite scientific experiment developed by the University of Montpellier students as part of a Centre National d'Études Spatiales (CNES) call for student projects ...
Endemic orchids of Australia
Orchids of New South Wales
Orchids of South Australia
Orchids of Victoria (Australia)
Plants described in 1927