''Pterostylis puberula'', commonly known as the dwarf greenhood or snail greenhood is a species of orchid which is endemic to New Zealand. It has a rosette of pale yellowish, stalked leaves and a single silvery-white and green flower with relatively long, erect lateral sepals.

Description

''Pterostylis puberula'' 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 a large number of leaves. The leaves are egg-shaped, about long and on a petiole . Flowering plants have a similar rosette at the base of the flowering stem, a single silvery-white flower with pale green stripes and one or two small leaves with their bases wrapped around the flowering stem. The stem is up to high. 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 galea is tall, erect near its base then suddenly curves to about horizontal with a blunt or slightly pointed end. The lateral sepals are fused near their bases, almost closing the front of the flower and have erect, thread-like tips much taller than the galea. The labellum is not visible outside the intact flower. Flowering occurs in September and October.

Taxonomy and naming

''Pterostylis puberula'' was first formally described by Joseph Dalton Hooker and the description was published in ''

Flora Novae-Zelandiae The ''Flora Novae-Zelandiae'' is a description of the plants discovered in New Zealand during the Ross expedition written by Joseph Dalton Hooker and published by Reeve Brothers in London between 1853 and 1855. Hooker sailed on HMS ''Erebus'' as ...

''. 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 ...

(''puberula'') is a Latin word meaning "downy".

Distribution and habitat

The dwarf greenhood grows in scrubland in disjunct populations on the North and

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 ...

s and on the Three Kings Islands. It has recently only been sighted on Great Barrier Island,

Surville Cliffs North Cape () is the northernmost point of New Zealand's main islands. At the northeastern tip of the Aupouri Peninsula, the cape lies east and north of Cape Reinga. The name ''North Cape'' is sometimes used to refer just to the cape that is kn ...

and near Thames.

Conservation status

''Pterostylis puberula'' is classed as "threatened – nationally vulnerable" under the New Zealand Threat Classification System.

References

{{Taxonbar, from=Q15494598 puberula Orchids of New Zealand Plants described in 1853