Mysterious comings and goings of wild orchids

Another Life: They've widened the bend above the post office, where I used to push my bike up the hill from the library bus. Bus and bike belong to the past, but now, alas, so do the early purple orchids that shone from the bank there in May.

There were more on a rough corner of land beside me, but today it's fenced and full of sheep, so that's that. For early purples, it's a trip across the duach and up the rocky creggans. There, on moorland closed off from grazing, almost every pocket of soil is candled in spring with orchids in white, pink and purple, fading now as summer oozes in.

With all their capricious colour and randomly spotted leaves, the one thing early purples have in common (and this is official) is the unmistakable whiff of cats' urine, like a wrong year of Sauvignon Blanc. But the Irish Orchidacaea more than make up for this with the heady scents of butterfly orchids (intensified at dusk to bring pollinating moths) and we have no fewer than three kinds of fragrant orchid, so called. The common one, as orchid expert Brendan Sayers notes, stops you in your tracks "because, when you get close to it, the sweet scent of cloves envelops you, and you have no choice but to concentrate on the plant". The fragrance of Spiranthes romanzoffiana, Irish lady's tresses, is also sweet enough, but first you have to find it. It is a rare, endangered plant in this island and was singled out in the first set of all-Ireland conservation "action plans" published for consultation in February, in company with hare, corncrake and pollan (the island's rare whitefish, found mostly in Lough Neagh).

This orchid's far commoner relation, Spiranthes spiralis, or autumn lady's tresses, is also hard to find but simply because, at a mere hand's breadth tall, its tiny plants are easily hidden in the grass. It blooms in August on calcareous ground, like some of the hillocks above the duach, regularly dusted with limy shell-sand. Michael Longley, his silver beard lowered almost to the ground, found it there for me once and later wove it into a poem. And Brendan Sayers thinks it's the most beautiful orchid in Ireland, even if you need a magnifying glass to appreciate it to the full.

What you see then is a row of creamy-white bells, braided tightly in a spiral up the stem: one of the most exquisite designs among Ireland's wildflowers. Despite their tiny size, the bells reward visiting bees with a bead of nectar at the base of their frilly lips; the bees work counter-clockwise up the stem.

Irish lady's tresses, the rare and equally miniature relation, blooms a month earlier, in July, and can have as many as 35 creamy flowers packed into three spiralling rows. It is named, as one hopes, for a Russian count, Nikolai Romanzoff, who paid for an exploratory voyage to the US west coast that also found the California poppy. And this is the point: before the orchid was found near Castletownbere, Co Cork, in 1810, it was considered an almost exclusively North American plant. Later finds along the western fringes of Ireland and Scotland's Hebrides have still left it with "critically low populations" as a European species.

How it got here is debatable: an introduction, as some claim, or an Ice Age survivor? It has spread dramatically since 1810, especially to wet pastures and lakeshores in the counties around Lough Neagh and around the big western lakes. Its erratic appearances and disappearances have added to its mystery: even since 2000, a dozen new sites have been found in Galway and Mayo.

The possible explanations for its rarity and odd comings and goings are "poorly understood", which is now the cue for much fieldwork and research before management plans can be prepared on their target dates. Overgrazing, habitat drainage, fertiliser, silage cutting, human trampling at lakeshores, depredation by slugs and rabbits (even geese in some places) are all possible threats.

A "negative feedback" theory being explored in research by the National Parks and Wildlife Service is that, because the orchid is so rare, insufficient Irish insects bother to pollinate it, and, because they don't, low seed production keeps it rare. I don't know what you do about that.

What you don't do is defy the wildlife law and dig it up to take home (there's another American Spiranthes species available in some Irish garden centres and great for a boggy window-box).

Meanwhile, enjoy the two orchids in An Post's new range of Irish wildflower stamps, typically found in the Burren and painted by Susan Sex (see her Iish Lady's Tresses, left). It's almost worth posting extra parcels just for the pleasure of using her spring gentians, gloriously blue at €10.