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previously: Habenaria chlorantha and Habenaria virescens
Plants growing in the open are robust, while those in shaded woodland are taller and more slender. The flower spike, 20-60 cm tall, has two large, elliptical, shiny, bluish-green basal leaves and up to five smaller, pointed stem leaves. There are 10-40 white flowers in an open spike, the flowers borne well away from the stem on S-shaped ovaries. The ovate, wavy-edged lateral sepals spread outwards and downwards, the smaller upper sepal and two petals forming a broad, semicircular hood. The translucent lip is long and strap-shaped with a greenish tip, the spur at the base being up to 25 mm long, lying right across the flower spike and curving slightly downwards. The two pollinia diverge and are set wide apart at the base of the column, giving a clear view down into the spur. The scent is sweet and strong, particularly at night. The white flowers are highly reflective and show up well in dim light.
Lesser Butterfly-orchid is very similar, but the two pollinia are parallel and lie close together, obscuring the entrance to the spur. Aberrant flowers are not uncommon: some lack both lip and spur, others have no lateral sepals but a sepaloid lip with no spur, yet others have a spur but no lip. Flowers with all three petals resembling a lip, complete with spur, have been recorded in Skye.
Hybrids between the two butterfly-orchids have been confirmed in Scotland. The so-called hybrid with Small-white Orchid in Scotland proved to be a peloric Greater Butterfly-orchid.
Most commonly found on well-drained, calcareous soils, on downland, old pastures, hill hay meadows, woodland such as that on the heavier soils below chalk hills, and occasionally in calcareous sand dunes. Rarely found on slightly acid moorland.
Although bumblebees visit the flowers, they have too short a proboscis to reach the nectar in the spur. Pollinators include Silver-Y moth and Elephant and Small Elephant Hawk-moths. Seed is set in 70-90% of capsules.
Many sites were lost to woodland clearance and the improvement of upland pastures during the last century. The development of a dense woodland canopy suppresses flowering, but subsequent clearance can lead to a dramatic reappearance of hundreds of flower spikes, even after an interval of more than 50 years.
Widely distributed in southern England,Wales, north-west England, western Scotland and the northern half of Ireland. It is absent from Orkney, Shetland and the Outer Hebrides.
Height: up to 60cm
No. of flowers: up to 40
May to July
This is a link to BritainsOrchids
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