''Pterostylis commutata'', commonly known as the midland rustyhood is a plant in the orchid family
Orchidaceae and is
endemic to
Tasmania. It has a
rosette of leaves near its base and up to five translucent white and green flowers with a hairy, insect-like
labellum. It is only found in a small area near
Tunbridge and
Ross Ross or ROSS may refer to:
People
* Clan Ross, a Highland Scottish clan
* Ross (name), including a list of people with the surname or given name Ross, as well as the meaning
* Earl of Ross, a peerage of Scotland
Places
* RoSS, the Republic of Sou ...
.
Description
''Pterostylis commutata'' 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 between six and ten leaves. Each leaf is long and wide. Flowering plants have a rosette at the base of the flowering stem but these are usually withered by flowering time. Up to five translucent white flowers with green markings and long and wide are borne on a flowering spike tall. The flowers lean forward slightly and there are three or four stem leaves wrapped around the flowering stem. 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 form a hood called the "galea" over the column with the dorsal sepal having a thread-like tip long. The
lateral sepals are the same width as the galea, dished and have densely hairy edges. They taper suddenly to narrow, thread-like tips long and parallel to each other. The
labellum is green or brown, thin and insect-like, long and about wide. The edges of the labellum are wavy, with short, bristly hairs and there are two longer bristles near the "head" end. Flowering occurs from December to January.
Taxonomy and naming
''Pterostylis commutata'' was first formally described in 1993 by
David Jones from a specimen collected near Ross and the description was published in ''
Muelleria''.
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 ...
(''commutata'') is derived from the Latin word ''commutatus'', 'changed', referring to the divergence of this species following isolation from related species.
Distribution and habitat
The midlands rustyhood grows in grassy woodland near Tunbridge and Ross.
Conservation
''Pterostylis commutata'' is listed as "critically endangered" under the (CR) under the
Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act) and as "endangered" under the Tasmanian Government ''
Threatened Species Protection Act 1995''. It is only known form an area of about and the largest of the five populations only contains seventeen plants. The main threats to the species' survival include agricultural activities, habitat alteration and weed invasion.
References
{{Taxonbar, from=Q15491299
commutata
Orchids of Tasmania
Plants described in 1993