The New Zealand Plant Conservation Network

Species

Pterostylis irsoniana

Etymology

Pterostylis: winged column

Common Name(s)

Greenhood

Current Conservation Status

2012 - Not Threatened

Conservation status of New Zealand indigenous vascular plants, 2012
The conservation status of all known New Zealand vascular plant taxa at the rank of species and below were reassessed in 2012 using the New Zealand Threat Classification System (NZTCS). This report includes a statistical summary and brief notes on changes since 2009 and replaces all previous NZTCS lists for vascular plants. Authors: Peter J. de Lange, Jeremy R. Rolfe, Paul D. Champion, Shannel P. Courtney, Peter B. Heenan, John W. Barkla, Ewen K. Cameron, David A. Norton and Rodney A. Hitchmough. File size: 792KB

Previous Conservation Status

2009 - Not Threatened
2004 - Not Threatened

Authority

Pterostylis irsoniana Hatch

Family

Orchidaceae

Flora Category

Vascular - Native

NVS Species Code

PTEIRS

Structural Class

Orchids

Synonyms

None (first described in 1950)

Distribution

Endemic. North and South Islands, from East Cape South to Wellington, then mainly in the West of the South Island to about Haast.

Habitat

Lowland to subalpine (montane to subalpine in the northern part of range) up to 1200 m a.s.l. In beech (Nothofagus Blume) forest, Podocarp forest, frost flats and subalpine scrub. Often in deep drifts of leaf litter or on the margins of sphagnum bogs.

Features

Terrestrial, summer-green, tuberous perennial herb. Plants solitary or in colonies, up to 350 mm tall when flowering. Stem stout, erect, terete, smooth, internodes < to << leaves, dark green to reddish green. Leaves 3-5(-8), all cauline, increasing in size from base to top, upper most leaves overtopping flower; largest leaf on stem (40-)150(-200) x 5-12(-18) mm; dark green to yellow-green often tinged with red or pink, linear-lanceolate, widest near sheathing base, tapering to an acuminate apex; more or less keeled, midrib prominent, yellow to yellowish cream, lateral veins less obvious. Flower solitary, reddish green. Ovary erect to slightly inclined, dark green deeply ribbed, ribs often reddish. Dorsal sepal (15-)25(-30) mm long, the erect part usually longer than the rest, apex acuminate to shortly caudate; lateral sepals diverging at a narrow angle, apices acuminate to shortly caudate, not greatly exceeding the galea. Petals slightly shorter than dorsal sepal, apices narrow-acuminate. Labellum narrowly deltoid and protruding, gently arched but consistently curled sharply downwards at the narrow, cucullate, apex deeply emarginate; midrib not evident in distal portion, proximally prominent and more or less papillose or bearing sparse calli, terminating basally in a prominent, projecting dark red to maroon-black callus. Column almost as long at labellum; stigma long and narrow.

Similar Taxa

The distinctive curled labellum with an deeply emarginate tip (like a drainers scoop), and prominent dark medial basal callus facing the column are key distinctions that separate this species for all other Pterostylis in New Zealand. The flowers are usually dark green tinged with red.

Flowering

October - January

Flower Colours

Green,Red / Pink

Fruiting

December - April

Propagation Technique

Difficult - should not be removed from the wild. asic orchid mix consists of 2 parts medium coarse sand, ideally clean river sand; 2 parts soil, humus or leaf-mould; 1 part weathered sawdust or rotting wood; 1 part granulated bark. For Pterostylis shade of 50% and pots kept evenly moist.

Threats

Not Threatened.

Chromosome No.

2n = 44

Endemic Taxon

Yes

Endemic Genus

No

Endemic Family

No

This page last updated on 31 Oct 2014