orchids are everywhere

Forest and Bird, Issue 293, 1 August 1999, Page 32

orchids

are everywhere

ST GEORGE.

New Zealand has more than 120 native orchids,

‘all beautiful’, according to IAN

ild native orchids are common plants in New Zealand if you know what to look for. Far from being flowers of the tropical jungle, most orchids originate in temperate zones and New Zealand has more than 120 species. While a few are rare, many are in some places as common as grass. True, most of the native orchids are not brightly coloured, nor do they generally have a strong fragrance to attract insect pollinators (uniquely, two thirds of our orchids are self-pollinating), but their beauty takes your breath away. Orchids are everywhere. They occupy just about every habitat in New Zealand from brackish estuarine swamps to alpine herbfields. In between, they may be found in front lawns and dark forests, on tree trunks, road verges, rocky outcrops, scrubby hillsides, and dry banks along bush tracks. Orchids may take root on traffic islands in cities, in the spray zones of waterfalls, on moss hummocks, or in exotic pine forests. There are more than 40 species in the far south, even more in the far north, and everywhere between. Stewart Island alone has dozens. Identifying orchids is probably harder than finding them but knowing what to look out for helps sort them from other small plants. Their shapes vary from the tiny ground-hugging spider orchids, to more familiar sprays which hang from forest trees, and the upright, flowering stalks of the grass orchids. What they all have in common is the unique structure of the orchid flower. Orchids have evolved from lilies, which have three petals and three sepals of the same shape, surrounding six stamens (male parts) and three stigmas (female parts). In orchids, at some inspired evolutionary moment, the male and female parts joined

into one central floral structure called the column. The three sepals and three petals surround this single column. Furthermore, in orchids the petals and sepals are often different from each other, with one sepal forming the hood protecting the flower, and one petal, the lip, which, especially in exotic orchids, is often curiously coloured and shaped to lure insects. The pioneer botanical writers, Laing and Blackwell, thought their variety looked like ‘swans, pelicans, the skin of the tiger and of the leopard, the eyes and teeth of the lynx, the face of the bull, the grin of the monkey, the head of the serpent, the tail of the rattlesnake, frogs, lizards, even the head of the extinct Dinotherium’. To be given a common name plants must be common (or if they are uncommon they have to be dangerous or delectable). Several of the New Zealand groups (genera) are

common, and deservedly recognised with common names; in contrast, only a few individual species are. To study and discuss orchid species at anything more than the most superficial level, you simply have to learn the scientific names. Here are samples of some of the major groups. —

CORYBAS (below)

‘Spider orchids’ is a term used in many countries for orchids with long petals and sepals. Our spider orchids are Corybas. There are 13 named species and about another half-dozen so far unnamed. Most have a broad flat leaf with a flower where the hood and lip form a tube surrounded by long ‘feelers’ formed from the other sepals and petals. Corybas oblongus grows at any shaded trackside, often in moss, its mottled leaves flat to the surface, its flower a fringed purple gem.

THELYMITRA (right)

The New Zealand ‘sun orchids’ are called Thelymitra. There are 15 named species and another six unnamed forms. Here the flower parts are similar, as in lilies, and it is the central column that varies from one species to another. The flowers range from white to pink to blue and open best on warm, humid, sunny days. Thelymitra cyanea startles with its brilliant blue flowers as you walk through the alpine bogs above Lake Dispute near Queenstown.

PTEROSTYLIS (below)

Our ‘greenhoods’ are Pterostylis, with 27 species and a few yet to be named. The biggest is tutukiwi, the standing kiwi, Pterostylis banksii. In this orchid the flower is a curved tube of its zipped-together parts, the lip mobile within, a spring-trap for insect pollinators. The hood and sepals are elongated in most species. Many have red markings on the mostly-green flowers, as this unnamed form from south Otago’s Catlins shows.

CALADENIA (above)

The Caladenias are perhaps the most beautiful. Six species have been described, and there is still controversy about which is which. Most are hard to find, being small and few-flowered, with a preference for a solitary existence in undisturbed scrub habitats. A sudden awareness of the bright pink stars against a drab background of leaf litter and debris is always a delight.

CALOCHILUS (above right)

Weirdest are the ‘beardies. Calochilus is a group of three transtasman vagrants which have established themselves in New Zealand, but nowhere in great numbers. All have hairy lips which, when associated with the dark shiny ‘eyes’ on the column-wings, give flowers the remarkable appearance of a bearded face. Calochilus robertsonti grows in sparse grass under introduced eucalypts at the roadside at Iwitahi near Taupo.

EARINA AUTUMNALIS (right)

We have seven perching orchids — plants with long rhizomes that cling to the surface Of) trees’ or rocks... Two . are Bulbophyllum, bulb-leaf orchids, growing in often quite big mats of tiny connected bulbs, the new ones topped by leaves, with inconspicuous flowers in the spring. They grow on the trunks or low branches of trees, or on rocks. Two more are Drymoanthus, growing out on the smaller branches and even twigs of smaller trees, with rosettes of 10 centimetre-long green leaves, beneath which arise stems bearing many small flowers. Two are Earina: raupeka, the Easter orchid (pictured), flowers through autumn into the early winter, its racemes of fragrant white flowers filling the evening air with perfume. Peka-a-waka has grassy leaves and branching stems of cream and yellow flowers forming large clumps in the trees.

GASTRODIA (below)

The ‘potato’ orchids, Gastrodia, are brownish plants, tall and many-flowered, quite lacking in the green pigment chlorophyll, and so unable to photosynthesize. As a consequence, potato orchids are obliged to depend on a close association with a soil fungus for nutrition. All four of the New Zealand Gastrodia are ‘epiparasites, infected by fungi and living on the carbohydrates the fungi break down from the soil and from the roots of other plants. The tubers of Gastrodia are the size of kumara, and were roasted, dried and eaten by Maori, notably the foraging Tuhoe. The flower is a tube of fused parts containing the column and lip. Dull and unattractive perhaps, but one of them delights incongruously with the fresh smell of freesias; its tall stems and multiple flowers buzz with insects attracted to that heavy fragrance on the evening air.

WINIKA (left)

The most showy of our perching orchids is the genus Winika which often forms colonies of two or more metres across. The yellow-branching canes, feathery green leaves, and white flowers with purple markings make a stunning sight as they droop into lakeside water, or feather the trunk of a great rimu.

MICROTIS (above)

The ‘onion’ orchids and the ‘leek’ orchids (Microtis and Prasophyllum) are perhaps the most common. Certainly Microtis can be found everywhere in New Zealand, occupying every well-lit ecological niche you can think of, even infesting urban flower-pots, suburban lawns, city traffic islands, and every trackside in the country. Stems of many tiny, insignificant, green flowers at first seem like weeds, but close study shows the tiny structures and tidy symmetry of the orchid flower. A number of our orchids are Australian migrants, their light seed carried over on the westerlies. Some thrive; others, lacking either their insect pollinator or the right soil fungus, survive for a time then disappear. Since the New Zealand landmass separated from Australia, between 80 and 55 million years ago, we have drifted a long way apart. Many of our species have evolved to show differences from their transtasman siblings, and several genera of orchid, a number of them with a single species, have developed exclusively here. The odd-leaved orchid, Aporostylis; the non-green epiparasite Danhatchia; the alpine Waireia; and Winika itself, exist only in New Zealand. The isolation of our islands has resulted in the evolution of many orchids peculiar to this country. IAN ST GEORGE is editor of the New Zealand Native Orchid Group’s Journal, and the author of Nature Guide to the New Zealand Native Orchids, published this month by Random House. He is a medical practitioner in Wellington.