''Pterostylis irwinii'' is a species of greenhood orchid endemic to New Zealand. Flowering plants have erect, linear leaves on the flowering stem while non-flowering plants have a rosette of egg-shaped leaves. There is a single green flower with translucent white stripes and reddish-brown tips.

Description

''Pterostylis irwinii'' 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 which often grows in loose colonies. Non-flowering plants have a rosette of two or three, more or less egg-shaped leaves which are long and wide. Flowering plants have a single flower long and wide on a reddish flowering stem tall with three to five stem leaves with their bases wrapped around the stem. The stem leaves are linear to lance-shaped, long and wide. 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 is long, wide and has a rough surface. It is erect near its base, then curves forward with the dorsal sepal longer than the petals. The lateral sepals are more or less erect with narrow tips long with a deep notch in the sinus between them and a wide gap between them and the galea. The labellum is long and about wide, curved, reddish-brown and protrudes above the sinus. Flowering occurs between October and January.

Taxonomy and naming

''Pterostylis irwinii'' was first formally described in 1997 by David Jones, Brian Molloy and Mark Clements and the description was published in ''The Orchadian''. 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 ...

(''irwinii'') honours J. Bruce Irwin who collected the type specimen at

Erua Erua is a small town on the North Island Central Plateau in New Zealand. The town is located on New Zealand State Highway 4 immediately to the south of the town of National Park. The town is administered by the Ruapehu District Council and f ...

near the Tongariro National Park in 1991.

Distribution and habitat

Irwin's greenhood seems to prefer damp positions in tall forest or steep hilly places with

basic BASIC (Beginners' All-purpose Symbolic Instruction Code) is a family of general-purpose, high-level programming languages designed for ease of use. The original version was created by John G. Kemeny and Thomas E. Kurtz at Dartmouth College ...

rocks such as limestone. On the

North Island The North Island, also officially named Te Ika-a-Māui, is one of the two main islands of New Zealand, separated from the larger but much less populous South Island by the Cook Strait. The island's area is , making it the world's 14th-largest ...

it occurs on the Waimarino River floodplain and near

Cape Palliser Cape Palliser is a promontory on the southern coast of New Zealand's North Island and is the southernmost point of the North Island; it is in fact considerably farther south than Nelson or Blenheim in the South Island. It is located at the easte ...

. On the

South Island The South Island, also officially named , is the larger of the two major islands of New Zealand in surface area, the other being the smaller but more populous North Island. It is bordered to the north by Cook Strait, to the west by the Tasman ...

it grows in the north west as far south as the

Buller River The Buller River ( mi, Kawatiri) is a river in the South Island of New Zealand. One of the country's longest rivers, it flows for from Lake Rotoiti through the Buller Gorge and into the Tasman Sea near the town of Westport. Within the Bulle ...

with a few observations further south.

Conservation

''Pterostylis irwinii'' is classed as "threatened and nationally endangered" under the ''New Zealand Threat Classification System''.

References

{{Taxonbar, from=Q15491708 irwinii Orchids of New Zealand Plants described in 1997