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Orchids of the British Isles - Tresses

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The shield of the Science, Mathematics and Engineering faculty of the h2g2 University.Orchids of the British Isles - Introduction
Animal Nomenclature | Orchids of Bogs, Fens and Marshes | Dactylorhiza | Helleborines (Cephalanthera) | Helleborines (Epipactis) | Insect Mimics
Lady's Slipper Orchid | Miscellaneous Orchids | Orchis | Saprophytes | Tresses | Twayblades

Autumn Lady's Tresses Spiranthes spiralis

The Autumn Lady's Tresses, previously known as Spiranthes Autumnalis, is not named because of its flowering time – it tends to flower from around mid-August. The flower stem emerges from out of the ground and can reach 15cm in height. By this time, the leaves have long since withered and died; they start to grow around late autumn (hence the name), forming a rosette of bluish-green leaves. The leaves are carried all through winter and start to die back in early summer.

Once the leaves have faded, the flowers take over. At intervals as the flower stem grows, leafy bracts appear that continue to the top of the stem. It is out of the upper half of these bracts that the flower buds are produced in a spiral to the top of the stem. Up to 20 white, trumpet-shaped flowers appear, opening from the bottom upwards. It is only the bottom petal that is different, and this forms a small lip which is frilled around the edges. Down the centre of the lip there is a channel which is green in colour, and this is where the honey-scented nectar is produced.

This orchid prefers to grow in dry, well-drained grassland. It likes chalky or limestone soils and can be found growing on cliff-tops near the sea. It can also be found on sand dunes, lawns and in churchyards. The one thing it must have is short grass in which to flourish; the reward being thousands of small white flowers.

Bumblebees are known to pollinate this orchid, though other insects are attracted to the strong scent of honey the nectar produces. It can take up to 11 years for this orchid to mature and flower from seed. After flowering the plant can remain dormant underground for years before emerging again to flower.

Summer Lady's Tresses Spiranthes aestivalis

The Summer Lady's Tresses has not been recorded flowering in the British Isles since 1952. Although there has been the occasional reported sighting, none has been confirmed, and it is believed this orchid is now extinct in the wild. It was first recorded in 1840, growing in the New Forest in Hampshire. It grew in wet boggy ground alongside rushes on sphagnum moss. The last-known photograph was taken in 1937.

It is thought that draining of the boggy conditions this plant loved has been a major factor in its extinction, and the over-collecting of specimens played a big role. Some museum herbarium1 sheets have as many as five or six plant specimens on them, which include the tubers. In the Channel Islands this orchid was last recorded in Guernsey in 1914 and in 1925 in Jersey. This was, again, believed to be due to the draining of sites and over-collecting.

Irish Lady's Tresses Spiranthes romanzoffiana

Despite the name, this orchid grows in a few sites in Scotland and on one site in Devon.

It used to be called Spiranthes gemmipara because it was thought that the plants in southern Ireland were a different species to the ones found in the north of Ireland and Scotland. Tests have since proved that this is not the case, although recent work by the Royal Botanic Garden, Edinburgh, has shown that there are two different genetic species in Scotland.

In Scotland and the north of Ireland, the leaves of this orchid are long and narrow and yellowish green. In southern Ireland and Devon, the leaves are broad and flat. The flower stem emerges from the centre of the leaves. It can reach up to 30cm in height and leafy bracts are produced at intervals along the stem. The flowers are produced in three spirals, each overlapping the other, giving the appearance of a twisted cord with flowers poking out from between. The flowers are tubular, with the outer petals wrapping around to form the tube. The inner petals flare at the top, while the lower lip folds down. The lip is marked with green veins against the white of the petals.

This is another orchid of damp marshy ground, preferring to be close to the edge of lakes and rivers. In Scotland it has been found growing as a marginal plant on the edge of lochs, where the water is extremely shallow (no more than an inch deep) and covered with sphagnum moss. Although it is said that this orchid flowers best once it has been trampled over by winter-grazing cattle, there is no scientific proof that this is the case.

It is not clear whether any pollination by bees occurs on this orchid in the British Isles. One of the largest populations has not set any seed in five years. It is therefore believed that this orchid can reproduce by sending up new shoots from the existing rhizome.

Creeping Lady's Tresses Goodyera repens

This orchid is not in the same genus as the others mentioned in this entry. In the USA, it is called the Lesser Rattlesnake Plantain. It has a large root system of rhizomes which creep underground, from which rosettes of long oval pointed leaves appear. The leaves are covered in pale veins which give the appearance of netting covering the leaves.

From the centre of the leaves the flower stem grows; it can reach up to 35cm in height. The flowers are white and covered with downy hairs, and all the flowers twist to face the same direction so it looks as if the orchid is only flowering on one side. The outer petals flare out from the base of the flower, while the upper petals form a hood. The lower petal forms a tongue, inside which the bright orange anthers are enclosed. Pollination is done mostly by small bumblebees Bombus pratorum, although there is also vegetative multiplication.

Confined mostly to Scotland and one or two pockets in Norfolk, this orchid likes to grow in coniferous woodland, particularly under Scots Pine.

1A collection of dried plant material laid onto sheets and systematically recorded.

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