Pterostylis irwinii

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Irwin's greenhood
Scientific classification Red Pencil Icon.png
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Monocots
Order: Asparagales
Family: Orchidaceae
Subfamily: Orchidoideae
Tribe: Cranichideae
Genus: Pterostylis
Species:
P. irwinii
Binomial name
Pterostylis irwinii

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.

Contents

Description

Pterostylis irwinii is a terrestrial, perennial, deciduous, herb 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 40–150 mm (2–6 in) long and 30–50 mm (1–2 in) wide. Flowering plants have a single flower 35–45 mm (1–2 in) long and 10–12 mm (0.4–0.5 in) wide on a reddish flowering stem 150–200 mm (6–8 in) tall with three to five stem leaves with their bases wrapped around the stem. The stem leaves are linear to lance-shaped, 60–170 mm (2–7 in) long and 4–5 mm (0.16–0.20 in) wide. The dorsal sepal and petals are fused, forming a hood or "galea" over the column. The dorsal sepal is 43–48 mm (1.7–1.9 in) long, 14–16 mm (0.55–0.63 in) 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 24–27 mm (0.9–1 in) long with a deep notch in the sinus between them and a wide gap between them and the galea. The labellum is 15–18 mm (0.6–0.7 in) long and about 3 mm (0.1 in) wide, curved, reddish-brown and protrudes above the sinus. Flowering occurs between October and January. [2] [3]

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. [1] The specific epithet (irwinii) honours J. Bruce Irwin who collected the type specimen at Erua near the Tongariro National Park in 1991. [4]

Distribution and habitat

Irwin's greenhood seems to prefer damp positions in tall forest or steep hilly places with basic rocks such as limestone. On the North Island it occurs on the Waimarino River floodplain and near Cape Palliser. On the South Island it grows in the north west as far south as the Buller River with a few observations further south. [2] [3]

Conservation

Pterostylis irwinii is classed as "threatened and nationally endangered" under the New Zealand Threat Classification System. [5]

Related Research Articles

<i>Pterostylis coccina</i> Species of orchid

Pterostylis coccina, commonly known as the scarlet greenhood, is a species of orchid endemic to eastern Australia. As with similar greenhoods, the flowering plants differ from those which are not flowering. The non-flowering plants have a rosette of leaves flat on the ground but the flowering plants have a single flower with leaves on the flowering spike. In this species, the rosette leaves are relatively large and dark green, and the flowers are white, and bluish-green or red. It grows in New South Wales and north-eastern Victoria.

<i>Pterostylis trullifolia</i> Species of orchid

Pterostylis trullifolia, commonly known as the trowel-leaved greenhood, is an orchid species endemic to New Zealand. As with similar orchids, the flowering plants differ from those which are not flowering. The non-flowering plants have a rosette of wrinkled, trowel-shaped leaves but the flowering plants have a single flower with a bulging, platform-like sinus between the lateral sepals and leaves on the flowering spike.

<i>Pterostylis banksii</i> Species of orchid

Pterostylis banksii, commonly known as greenhood or tutukiwi, is a species of orchid endemic to New Zealand. Non-flowering plants have a rosette of leaves. Flowering plants have leaves on the flowering stem, some of which reach above the single relatively large, green flower with translucent white stripes. It is the most common, widespread and largest New Zealand greenhood and is found on both of the main islands.

<i>Pterostylis atrans</i> Species of orchid

Pterostylis atrans, commonly known as the dark-tip greenhood or blunt-tongue greenhood, is a species of orchid endemic to south-eastern Australia. As with similar greenhoods, plants in flower differ from those that are not flowering. The non-flowering plants have a rosette of leaves flat on the ground, but the plants in flower have a single flower with leaves on the flowering spike. In this species, the flower is green and reddish brown with a protruding sinus and small club-like tips on the ends of the lateral sepals.

<i>Pterostylis dolichochila</i> Species of orchid

Pterostylis dolichochila, commonly known as the long-tongued shell orchid, is a species of orchid endemic to southern Australia. 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 have a single flower with leaves on the flowering spike. This greenhood has a green and white flower with reddish-brown stripes and a sharply pointed dorsal sepal.

<i>Pterostylis foliata</i> Species of orchid

Pterostylis foliata, commonly known as the slender greenhood, is a species of orchid widespread in south-eastern Australia and New Zealand. Flowering plants have a rosette of three to six, dark green, crinkled leaves crowded around the flowering stem and a single dark green and brown flower with a deep V-shaped sinus between the lateral sepals.

<i>Pterostylis longipetala</i> Species of orchid

Pterostylis longipetala, commonly known as the curved greenhood, is a species of orchid endemic to eastern Australia. As with similar greenhoods, the flowering plants differ from those which are not flowering. The non-flowering plants have a rosette of leaves flat on the ground but the flowering plants have a single flower with leaves on the flowering spike. This greenhood has dark green, brown and white flowers which lean slightly forwards and have sharply-pointed petals and a long, curved labellum.

Pterostylis agathicola, commonly known as the kauri greenhood, is a species of orchid endemic to the North Island of New Zealand. As with similar greenhoods, the flowering plants differ from those which are not flowering. The non-flowering plants have a rosette of leaves flat on the ground but the flowering plants have a single flower with leaves on the flowering spike. It grows almost exclusively in kauri forest and has a relatively large green and transparent white flower.

<i>Pterostylis brumalis</i> Species of orchid

Pterostylis brumalis, commonly known as the kauri greenhood or winter greenhood, is a species of orchid endemic to New Zealand. There is a rosette of leaves at the base of both flowering and non-flowering plants. Flowering plants have a white flower with narrow green stripes and a dorsal sepal which bends forward strongly while the petals spread widely, giving the flower a cobra-like appearance.

Pterostylis erythroconcha, commonly known as the red shell orchid, is a species of orchid endemic to South Australia. 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 have a single flower with leaves on the flowering spike. This greenhood has a white and green flower with reddish brown markings and a long, fleshy, curved labellum.

Pterostylis humilis is a species of orchid endemic to New Zealand. It has a rosette of leaves at the base of the plant and when flowering stem, leaves which usually obscure the dark green and white flower.

<i>Pterostylis irsoniana</i> Species of orchid

Pterostylis irsoniana is a species of greenhood orchid endemic to New Zealand. There are up to five erect leaves on the flowering stem with a single dark green flower with white stripes and a reddish tinge on the tips. It has a distinctive curved labellum with a curled tip with a dark red callus.

Pterostylis micromega, commonly known as the swamp greenhood, is a species of greenhood orchid endemic to New Zealand. Both flowering and non-flowering plants have a rosette of leaves while flowering plants also have a single, relatively large whitish flower with a pointed dorsal sepal. The flower colour and pointed dorsal sepal are unique in New Zealand Pterostylis.

Pterostylis montana is a species of greenhood orchid endemic to New Zealand. Flowering plants have erect, linear leaves on the flowering stem with a single green flower with translucent white stripes and an unusual twisted labellum.

Pterostylis paludosa, commonly known as swamp greenhood, is a species of greenhood orchid endemic to New Zealand. As with similar orchids, plants in flower differ from those that are not. Those not in flower have a rosette of leaves on a short stalk but plants in flower lack a rosette and have a single flower with leaves on the flowering spike. This greenhood has a translucent white flower with pale to yellowish-green stripes.

Pterostylis porrecta is a species of greenhood orchid endemic to New Zealand. Flowering plants have spreading, grass-like leaves on the flowering stem and a single small, transparent white and green flower with the lateral sepals held close to horizontally in front of the flower.

<i>Pterostylis reflexa</i> Species of orchid

Pterostylis reflexa, commonly known as the dainty greenhood, is a species of orchid endemic to New South Wales. As with similar greenhoods, the flowering plants differ from those which are not flowering. The non-flowering plants have a rosette of leaves flat on the ground but the flowering plants have a single flower with leaves on the flowering stem. This greenhood has a relatively large white, green and light brown flower with a long, curved dorsal sepal and a protruding labellum.

Pterostylis rogersii, commonly known as the curled-tongue shell orchid, is a species of orchid endemic to the south-west of Western Australia. 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 and have a single flower with leaves on the flowering spike. This greenhood usually has a white and reddish-brown striped flower with a long, curved labellum and is found along the south coast between Binningup and Esperance.

Pterostylis silvicultrix, commonly known as the Chatham Island greenhood or tutukiwi, is a species of orchid which is endemic to Chatham Island and nearby islands. Non-flowering plants have a rosette of leaves but flowering plants have leaves on the flowering stem, some of which reach above the single translucent white flower with dark green stripes. It is similar to Pterostylis banksii which occurs on both of the main islands of New Zealand but that species lacks the orange or reddish-brown tips on the flowers of this species.

Pterostylis venosa, commonly known as a greenhood, is a species of orchid endemic to New Zealand and which usually grows in colonies. Both flowering and non-flowering plants have a rosette of erect to spreading leaves, and flowering plants have a single yellowish-green to dark green flower with white stripes. It is similar to P. humilis.

References

  1. 1 2 "Pterostylis irwinii". World Checklist of Selected Plant Families (WCSP). Royal Botanic Gardens, Kew.
  2. 1 2 de Lange, Peter James. "Pterostylis irwinii". New Zealand Plant Conservation Network. Retrieved 30 June 2017.
  3. 1 2 "Pterostylis irwinii". New Zealand Native Orchid Group. Retrieved 30 June 2017.
  4. Smith, Val (2009). "Eponymous Orchids – James Bruce Irwin and Pterostylis irwinii". The New Zealand Native Orchid Journal. 112: 38. Retrieved 30 June 2017.
  5. "Conservation status of New Zealand indigenous vascular plants, 2017" (PDF). New Zealand Government Department of the Environment, Te Papa Atawhai. Retrieved 12 May 2020.