Wednesday, 15 September 2010

The last orchid of summer

Gather a group of naturalists together and the chances are that they will find something interesting to look at and to talk about. Last weekend, a friend’s wedding in Holt brought together a number of naturalists and, in the interval following the meal and speeches, we were able to pop outside and see a colony of Autumn Lady’s-tresses. This delicate little plant, the last of the orchids to flower each year, is a rare species in Norfolk and the opportunity to view it was not one to be missed.

Each plant is small (just 15 cm or so in height) and fragile in appearance. Approaching the lawn, I became aware of a smudge of white sitting just above the green of the lawn itself and creating the illusion of a thin low mist. This effect was caused by the white flowering spikes of Autumn Lady’s-tresses, a vertical spiral of crisp mint-white tubular flowers. To appreciate the flowering spikes fully, you had to get down on your hands and knees – no doubt a comical site to anyone watching us in our wedding finery. These orchids were very much my kind of plant; not garishly bright and shouty but soft and understated. Most had a dozen or so white flowers spiralling up the stem, some spiralled clockwise and others anti-clockwise. There were even a few plants which showed hardly any spiral at all.

Since the flowers open in succession, from the base of the stem upwards, there were some that had finished flowering but with others yet to open. This strategy helps to prevent self-pollination, the plants attracting bumblebees to carry pollen from one plant to another. This approach works well and cross-pollination is pretty much guaranteed. Even so, these orchids can reproduce vegetatively if necessary. Autumn Lady’s-tresses is a plant of southern Britain and is most commonly encountered south-west of a line running from Monmouth to Hastings but there are scattered colonies as far north as Cumbria. Many of the sites on which this orchid once occurred in East Anglia have been lost, invariably areas of damp grassland now drained. Autumn Lady’s-tresses is associated with short nutrient-poor grassland, where it is released from competition from larger and more dominant plants. This old lawn in Holt makes an ideal site, with careful mowing and control over the addition of nutrients keeping potential competitors in check. Proof of the success of the management approach can also be seen in the large number of grassland fungi recorded from the site. Since this species has been lost from more than half of its former range in Britain, it is reassuring to know that this particular site is likely to be secure for many years to come.

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