The Irish Lady's Tresses Orchid

Until recently the Irish lady's tresses orchid was thought to be very rare in the British Isles. A survey of this plant in Scotland, which I have recently conducted over nearly a decade, shows that it is in fact 'scarce' rather than very rare. Altogether it has now been found in twenty ten kilometre squares (the normal measure of distribution) in Britain, nineteen of which are in Scotland and one of which is in Devon. It does not occur in Wales. This survey also shows that Coll is one of the three main British centres for this orchid, the other two being in the Outer Hebrides.

The most fascinating fact about this orchid is its' world distribution. It is widespread in North America. The only other place where it occurs is in the British Isles, where it is restricted to Ireland, the west of Scotland and the site in Devon. In Scotland it is known from only seven of the Hebridean islands, including Coll and four small areas on the mainland. Why is it only found on the opposite sides of the Atlantic Ocean? A number of inconclusive theories have been put forward: the one that I have been working on is that the Greenland white-fronted goose introduced it into the British Isles from North America.

This orchid was first recorded in the British Isles from south-west Ireland in 1809 or 1810. Serendipity allowed that it was first recorded in Britain on the Isle of Coll in August 1921, although on this occasion it was misidentified. It was found by John B. Simpson of Edinburgh who described the site thus: '... in peaty soil overlooking beach deposits in part, but sometimes only on gneiss. But the soil may be limey, as there is a good deal of marble in the rocks near.' It has to be said that Simpson had doubts about his identification, which proved to be justified! Two of the mainland areas in Scotland where the orchid is known from are in Morvern and in Moidart. I believe that the MacLeans of Coll were responsible for accidentally introducing the plant into these areas.

Why is the orchid so called? Because the inflorescence is made up of small flowers which can be arranged in tight spiral rows, resembling neatly braided hair. These tight spiral rows are often absent in Scottish plants. The scent is of hawthorn. I understand that the late Mrs Hinkson described the scent on Coll as being so strong that, in a good flowering year, the plants could be detected at some distance on a warm, still day, even when they were out of sight behind a wall! Although I have seen dispersed populations of between one hundred and two hundred flowers, regrettably the days have gone when populations existed which could produce such a scent.

How can this orchid be identified? I should say first of all that because it has grass-like leaves it can only be found when it is in flower. However, in flower it is easy to spot. Unusually for orchids, it flowers late. It flowers on Coll from the middle of August to the beginning of September. So, if you find an orchid with white flowers at this time, the chances are that it will be this one. I have never found capsules of this orchid containing the dust-like seed. Perhaps the correct pollinating insects are not present in the British Isles? The flowers have fiddle-shaped lips. I have included a figure (for which my thanks go to Jo Nash) of the plant. There are some excellent photographs of the orchid taken on Coll in Wild Orchids of Scotland, B. Allan, P. Woods and S. Clarke, Royal Botanic Garden, Edinburgh, HMSO 1993. I know of at least two copies on Coll!

What kind of habitat does the orchid grow in? A favourite place to look is on old lazy-beds where the purple moor grass resembles a lawn. It is well known that there is no shortage of old lazy beds on Coll, which probably explains why the orchid is widespread on Coll, a fact which was realised as early as 1939/40. At the right time of year all such sites are worth examining for the orchid. It is also worth looking where the ground has previously been disturbed by ditching or fencing, or where hay has been put out for the cattle during the winter. Such disturbance seems to promote growth in the orchid.

Irish lady's tresses is not the only plant that grows on Coll that has what we call an amphi-Atlantic distribution. That is, only found on opposite sides of the Atlantic. The very rare American pipewort grows in a group of lochs and lochans on the island. There is a huge population in one of these lochs. The 'scarce' slender naiad has also been found in two lochs on Coll, although its' origin is obscure. Although it has not been found on Coll it is fascinating to note that another such plant, American pondweed, is only known as a native plant on this side of the Atlantic from a group of lochs and lochans on South Uist in the Outer Hebrides.

I am an amateur botanist in the sense that I do not get paid for my botanising. Indeed, it costs me money. However, I feel I must ask you never to pick this orchid, and, particularly because you cannot see it when it is not in flower, be very careful not to damage the plant through trampling. If anyone has any questions I would be very happy to try and answer them.

I know of a number of sites on Coll used by the Greenland white-fronted goose, either for feeding or roosting, where this orchid grows. If you are confident about identifying this goose (which I've never seen 'in the flesh', never having been in the Hebrides in the winter) and the orchid, I would be delighted to learn of such sites. If you are unsure about the orchid, please let me have a photograph or a slide taken fairly close-up. It is interesting to note that this orchid develops a lateral bud at the base of the stem during the growing season. The bud over-winters and produces the following year's aerial parts. It is possible that the goose uses these buds as a food source.

I hope that I have demonstrated that the orchid is not the only interesting species that occurs on Coll.

Frank Horsman
7 Fox Wood Walk, Leeds LS8 3BP