The New Zealand Plant Conservation Network

Species

Pterostylis irwinii

Etymology

Pterostylis: winged column

Common Name(s)

Greenhood

Current Conservation Status

2018 - Threatened - Nationally Endangered

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

2012 - Threatened - Nationally Vulnerable
2009 - Threatened - Nationally Endangered
2004 - Data Deficient

Qualifiers

2012 - DP, EF, Sp
2009 - DP, EF, Sp

Authority

Pterostylis irwinii D.L.Jones, Molloy, et M.A.Clem.

Family

Orchidaceae

Flora Category

Vascular - Native

Structural Class

Orchids

Synonyms

None (first described in 1997)

Distribution

Endemic. North Island: Waimarino River Plain near Erua and near Cape Palliser. In the South Island mainly in the north-west as far south as the Buller River, and also down the Wairau River. Exact distribution still unclear. Easily overlooked on account of its short flowering season.

Habitat

Montane (mostly above 600 m a.s.l.). Although exact habitat preferences are uncertain this species seems to prefer damp, shaded, or well-lighted situations in tall forest along river flats, or in steep hill country overlying primarily base-rich geologies (especially calcareous mud and siltstones, limestone, marble and soils derived from andesitic tephra).

Features

Terrestrial tuberous herb growing in diffuse colonies. Plants dimorphic. Sterile plants 60-100 mm tall; 2-3-leaved; leaves linear, 40-120 x 30-50 mm, dark green, entire acuminate. Flowering plants 150-200 mm tall, stems reddish. Leaves 3-5, cauline, widely spaced, spreading; lamina linear, 60-170 x 4-5 mm, dark green to bronze-green, glossy beneath, sessile, sheathing at base; margins entire; apex acuminate. Pedicel 20 mm long, slender. Ovary linear, 10-13 mm long, ribbed, reddish or red-brown. Flower solitary, 35-45 x 10-12 mm, erect, translucent white and dark green with red to red-brown suffusions in the apex of the galea and lateral sepals; galea shallowly gibbous at the base then erect before bending forwards, the apex erect to obliquely erect, the dorsal sepal much longer then the petals. Dorsal sepal ovate-lanceolate in outline when flattened, 43-48 x 14-16 mm, expanded near the base then tapered to the long-acuminate or attenuate apex. Lateral sepals obliquely erect to erect, hardly embracing the galea, leaving a very wide lateral gap to the petal margins, much of the labellum visible through this gap; upper part of sinus flat when viewed from the side, with a deep, relatively wide central notch when viewed from the front; internally the sinus projecting inwards as a small platform-like projection; conjoined part 14-16 x 8-10 mm, prominently scabrid, narrowed to 2.5 mm wide at base, tapered into the free points; free points 24-27 mm long, involute, tapered, erect, the tips extending above the galea. Petals obliquely linear-lanceolate, 30-33 x 3-4 mm, strongly falcate, long-acuminate, green with white stripes, red-brown toward the apex. Labellum erect, curved forwards in the distal third, the apex protruding prominently through the sinus in the set position; labellum hinge ligulate, 3 x 2 mm; lamina oblong-lanceolate, 15.0-18.0 x 3.2-3.5 mm, red-brown; apex subobtuse to acute; callus raised, 0.7 mm wide near apex; basal appendage 3.0-3.5 mm long, penicillate. Column 14-16 mm long, bent away from the ovary at 35 degrees at the base then erect, green and white; column foot 4 mm long. Column wings 6-7 mm long; basal lobe 3 x 1 mm, at an angle of about 35 degrees; apex obtuse; inner margins incurved, sparsely and shortly ciliate; mid-section 3 mm long, green; apical lobe 1.3 mm long, linear,obtuse. Stigma narrowly scutiform 3-4 x 2 mm, medial on the column, raised. Anther 1.8 mm long, very shortly rostrate. Pollinia linear-falcate, 1.5-1.8 mm long, yellow, mealy.

Similar Taxa

Easily recognised by the larger, somewhat narrow flowers with reddish suffusions in the galea and lateral sepals; obliquely erect to erect galea; erect to obliquely erect lateral sepals held well away from the galea so leaving a wide gap between the margins of the galea and the petals, and by the extremely sensitive, oblong-lacneolate, reddish-brown labellum.

Flowering

November - December

Flower Colours

Green,White

Fruiting

January

Propagation Technique

Difficult - should not be removed from the wild.

Endemic Taxon

Yes

Endemic Genus

No

Endemic Family

No

This page last updated on 28 Oct 2014