''Pterostylis nigricans'', commonly known as the dark greenhood, is a species of
orchid endemic to 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 lack a rosette at the base but have up to six tiny green, white and brown flowers which have a rough texture.
Description
''Pterostylis nigricans'' 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 three to eleven egg-shaped to heart-shaped leaves. Each leaf is long and wide on a
petiole long. Flowering plants have up to six well-spaced flowers long and wide on a flowering stem tall. Up to three leaf rosettes are arranged on separate stems at the base of the flowering spike. The flowers are green and white with a dark chocolate-brown tip and have a rough surface texture. 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 and has a short point. The
lateral sepals are erect, held closely against the galea with thread-like tips about long that do not project above the galea. The
sinus between the bases of the lateral sepals almost closes off the front of the flower and has a small notch in the centre. The
labellum is about long and wide and is not visible from outside the intact flower. Flowering occurs from March to May.
Taxonomy and naming
''Pterostylis nigricans'' was first formally described in 1988 by
David Jones and
Mark Clements from a specimen collected on
Stradbroke Island and the description was published in the ''Austrobaileya''.
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 ...
(''nigricans'') is a
Latin word meaning "blackish",
referring to the dark colour of the flowers.
Distribution and habitat
The dark greenhood grows in forest, scrub and heath in coastal and near-coastal areas of south-eastern
Queensland and in
New South Wales north of
Evans Head
Evans Head is a town in Richmond Valley Council of the Northern Rivers region of New South Wales, Australia. At the 2016 census, Evans Head had a population of 2,843 people. It is 726 kilometres north of Sydney, and 11 kilometres east off the ...
.
References
{{Taxonbar, from=Q15499438
Pterostylis, nigricans
Endemic orchids of Australia
Orchids of New South Wales
Orchids of Queensland
Plants described in 1988