This section is from the book "British Wild Flowers - In Their Natural Haunts Vol5-6", by A. R. Horwood. Also available from Amazon: A British Wild Flowers In Their Natural Haunts.
Unlike the Marsh Red Rattle this is not an Arctic plant, and does not occur in any ancient deposits. The range is throughout Europe, except Greece and Turkey or the N. Temperate Zone. It is found in every part of Great Britain, as far north as the Shetlands, up to 2000 ft. in the Highlands. It is native in Ireland and the Channel Islands, Red Rattle is an extremely local plant, though uniformly dispersed. It is an ericetal species, few heaths being without it. It also grows on commons, moors, and upland slopes of hills. It is associated with Tormentil, Heath Bedstraw, Harebell, Ling, Eyebright, Cow-wheat, and a hundred other upland wild flowers.
Photo. Flatten & Carnett - Red Rattle (Pedicularis sylvatica, L.)
The stems are smooth, tufted, clustered, unbranched except at the base, decumbent or prostrate, so differing markedly in habit from the Marsh Lousewort. It has a low, tufted, leafy stem. The leaves have lobes each side of a common stalk, with acute pinnae, and are divided nearly to the base.
The flowers are rose-colour, irregular, large, with an oblong, inflated, smooth calyx, which is unequal, 5-cleft, with leaflike lobes. The corolla has a slender tube (10-14 mm.), flattened lengthwise, and the upper lip is 2-dentate. The capsule exceeds the calyx, and is blunt.
Red Rattle is not more than 3 in. in height, being prostrate. The flowers bloom in May, June, and July. The plant is perennial and propagated by division.
Opposite pairs of the 4 anthers are contiguous along the inner edge, forming a box, and their outer edges adhere to the top of the tube or hood. The honey lies at the base of the ovary, 10-14 mm. from the mouth of the corolla, and the latter is compressed or flattened lengthwise, hence a humble-bee can only insert part of its head. To reach the honey the insect has to stretch the lips, and so opens the anther-cavity, and releases a shower of pollen on the fringe of hairs on the lower edge of the anthers, which thus falls on the head of the bee, when it has but just touched the projecting stigma, and is ready to be applied to the stigma in the next flower. The edge of the upper lip is rolled back, the inner armed with projecting teeth.
The flowers are visited by the Hymenoptera, Anthophora and Bombus.
The capsule splits open and allows the seed to fall out, or be blown by the wind, around the parent plant.
This pretty little heath and marsh plant is a humus-loving, parasitic plant, and grows only on heaths on humus soil.
The second Latin name suggests a woodland habitat, but it is addicted to open heathland or wet spongy tracts on hill-sides.
Red Rattle is also called Cock's-comb, Dead Men's Bellows, Honeysuckles.
Essential Specific Characters: 241. Pedicularis sylvatica, L. - Stem prostrate, branched below only, leaves pinnatifid, segments ovate. flowers rose-colour, calyx glabrous, oblong, angular. 5-fid.