Identifying orchids

Sun orchids (Thelymitra)

Sun orchid flowers generally require warmth and relatively wind-free conditions to open and some will only open in full sun (hence the name). The plants vary little in outward size and shape and each has a single hairless leaf originating near the base of the plant. The leaf is usually of limited use in identification, although a few species have distinctive leaf features.

Each plant can have up to twenty (and sometimes even more) colourful flowers but commonly the range is from one to five or six. Each flower is 1-2 cm wide and has 6 similar tepals (petals and sepals), which is unusual in an orchid. Flowers range in colour from white through pink to deep blue with markings that can be useful for identification. The centre part of the flower within the tepals is the column, which usually contains the key identifying features. The colour and shape of the column and the arms projecting from the column are all important identification features. They can often be used even on a dead or dry flower.

Plants are usually found in open areas, often on clay banks or soils, but also in wet or peaty areas with low vegetation. More species are found in the Far North of New Zealand than elsewhere.

Key features: Many flowers with 6 star-like tepals enclosing a complex and colourful reproductive structure - the column, its arms and wings.

Onion and leek orchids

Onion and leek orchids get their name from the tubular leaf from which the flower stem emerges, well up the stem. In the onion orchids the leaf extends well beyond the stem but in the leeks it remains upright against the stem. Onion orchids are greenish and leeks are more colourful.

The flowers are quite small, closely packed, ranging from a dozen to perhaps 100 per spike.

They are found in open areas, sometimes in wet places. Microtis unifolia is the most widespread. It is a particularly abundant species that can be found everywhere from native grasslands to the cracks in street pavements, and even your lawn or backyard.

Key features: Stems with many flowers emerging from a tubular leaf, perhaps at half its length or more.

Other orchids of open places

Three other genera are found in open places. Orthoceras is distinguished by having several leaves and is more common in the north.

Waireia usually has two leaves and is usually found in damp alpine areas.

The three bearded orchids are easily recognised by their very coarsely hairy labellum and often blueish-green single leaves.

Key features: Each has a hooded dorsal sepal and a prominent labellum hanging beneath.

Epiphytic orchids

The perching or epiphytic orchids are the most noticeable of our native orchids. They can be seen on the branches of trees in just about any native forest remnant throughout the country.

There are only eight species of epiphytic orchid, and none have large showy flowers. Dendrobium cunninghamii has the largest at 2 - 2.5cm., while the flowers of Bulbophyllum pygmaeum are only 2.5mm across. Taeniophyllum is the smallest species.

Fallen trees and branches are the best place to locate them. Several species can occasionally be found growing upon rocks and banks or even the forest floor.

Key features: The plants vary greatly in size and flower. The main common feature is a preference for branches or rocks with a thin covering of moss or lichen so their roots can breathe freely.

Greenhood orchids (Pterostylis)

There are over 36 species of greenhood orchids in NZ.

Their leaves come in a range of shapes and sizes, with grass-like leaves being the most common. Their flowers form a convex hood (or galea) which, in most species, is usually coloured green with translucent white stripes. They are mainly orchids of forest and scrub.

The greenhoods possess a sensitive labellum. When touched by a small insect, it flips backwards and traps the insect so it has to crawl over the stigma and past the pollen to freedom. Take care not to touch or bump the flower before you get a photograph. The lip usually resets itself after about half an hour.

Key features: Green or sometimes brownish, hooded flowers with a touch sensitive labellum visible inside.

Spider orchids (Corybas)

Spider orchids (Corybas) are small plants with a single broad leaf and single flower. They are found on damp banks or on the forest floor. Some species form quite dense colonies that carpet the ground. The solitary flowers of many of the species have very long thin sepals, which give the plants their spider-like appearance. Most species flower from August to November.

There still a number of undescribed species but about 25 are currently recognised. Some species show a lot of variation.

Key features: Flowers usually dark red, often with a green dorsal sepal capping the labellum; labellum forming a curved tube with a flared midlobe or “bib”; lateral tepals often very long and at least partly upright.

Caladenia and allied orchids

The Caladenias are very colourful, with finger-like petals and sepals that give them their name. They have a single hairy narrow leaf, with the flower stalk emerging from ground level. They have between one to three flowers that measure 10-20mm across.

Caladenias are mainly found on poor clay soils amongst scrub and light forest. They flower during spring to early summer in most districts, although flowering can be as late as February in alpine zones.

The tiny Adenochilus has a heart-shaped leaf and is common in red beech forest. Aporostylis is somewhat larger than a Caladenia and is common in alpine scrub and bogs

Key features: Four broad white to pink or red tepals, a varied dorsal sepal and a labellum with folded wings covered between with raised calli, and a hanging midlobe.

Gnat orchids

Gnat orchids are small orchids of forest and scrub. They have a single oval or heart-shaped leaf and usually 2-4 flowers. There are four known species.

The Pixie Cap Orchid (Acianthus) and the two virtually identical species of Cyrtostylis flower in winter or early spring. They are found in forest and amongst scrub and are not uncommon in some districts.

Townsonia is found only in damp mossy places amongst subalpine beech forest. It is found from Mt Ruapehu southward. It is rare in the North Island, and uncommon in the South Island.

Key features: Tiny delicate transluscent flowers and a single often broad heart-shaped, clasping leaf.

Potato orchids

The saprophytic orchids are brownish and have no leaves or chlorophyll. Instead they have a symbiotic association with a fungus that is parasitic upon a host tree root.

The potato orchids (Gastrodia) have large underground tubers that send up a flowering spike up to a metre tall and which can be covered in up to 40 bell-shaped flowers. By contrast Danhatchia is scarcely 20 cm tall, has few flowers, and is found near taraire or nikau.

The potato orchids flower over summer, and have become quite common beneath exotic pine forests. They have been known to appear in traffic islands in pine-bark chips or mulch; the seeds apparently coming along with the bark.

Key features: Brown leafless stems generally bearing many brownish, bell-shaped, pendant flowers.

Also see Guide to Gastrodia (PDF, 5.17 MB) by Jeremy Rolfe.

Bird orchids

Of the bird orchids, one (Chiloglottis cornuta) is quite common in forest, especially older pine plantations, whereas two others appear to be irregular visitors from Australia and unable to establish and spread. A further two are recent arrivals (in the last 30 years or so) and establishing. Bird orchids are distinguished by a knobbly labellum surface that can look like an insect. Established colonies can be quite large.

Key features: Two broad leaves, a variously ornamented labellum. Some very weird flower shapes.

Wet place spider orchids

A group of spider orchids occur in the flood zone along stream banks or in the spray of waterfalls, often forming large colonies. They have oblong to heart-shaped and clasping, thick leaves, often with dots along the margin. They are all rather similar. The dorsal sepal is long and pointed, lateral tepals long and thin and midlobe of the labellum is unusually triangular with a pointed bottom drip tip.

Key features: Streamside habitat; long lateral tepals and triangular labellum midlobe.

Swamp orchids

Three large orchids occur in water, or areas subject to regular flooding: Spiranthes australis, Cryptostylis subulata and Prasophyllum hectorii. They often occur amongst rushes or other wetland plants.

A few other orchids from the main genera such as Corybas carsei, Thelymitra cyanea and T. pulchella or Pterostylis micromega and P. paludosa also occur in swamps or wetlands. For those species visit their respective genera.

Key features: Swamp habitat, relatively large plants with many flowers.