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.
Though a true bog plant it belongs rather to southern types (not northern), and has not been discovered up to the present in any ancient deposits. In the North Temperate Zone it occurs in Europe, south of Belgium, except in Russia, E. Siberia, N. Africa, and Temperate S. America. In Great Britain it is found in every part of the country except Middlesex, W. Gloucs, Roxburgh, Stirling, Perth, Forfar, W. Ross, E. Sutherland, more particularly in the west. It is native in Ireland.
Bog Pimpernel, like many other paludal plants, has become scarce on account of agricultural improvements owing to drainage and cultivation. It is a typical bog plant, growing on spongy, peaty wastes, as well as in less peaty tracts or marshes richer in lime, and in wet meadows and damp places caused by perpetual springs or the overflow from lakes and rivers.
The stems are prostrate, ascending at the tip and rooting at intervals, creeping, numerous, round or square, smooth, branched with purplish joints. The leaves are opposite, nearly stalkless or but shortly stalked, small, egg-shaped, entire, smooth. The flowers are pink, large, borne on simple, erect, finally turned-back flower-stalks, 1-flowered, in the axils of the leaves. The flowers are bell-shaped, large, with dark veins. The calyx is shorter than the corolla and dotted with red. The corolla is wheel-shaped or funnel-shaped. The anther-stalks are connected below. The capsule opens by a transverse fissure in the centre. The cells where the capsule opens are linear and loose, but larger, more rounded elsewhere. The seeds are brown, flattened on one side, and toothed.
Photo Hinkins & Son - Bog Pimpernel (Anagallis tenella, Murr.)
Bog Pimpernel flowers from August to September. The height is about 3 in. It is perennial, propagated by division, and worth cultivating.
The flower is similar in form to that of Scarlet Pimpernel, but red or pink with darker veins. The anther-stalks are united at the base forming a cylinder, the flower campanulate, and rather large, the corolla is wheel-shaped and erect, and the anther-stalks are very hairy, filling the corolla, to prevent the honey from being spoilt by rain. The anthers are yellow, the style tapers, and is longer than the anthers, and the stigma is simple. It is not likely to be self-pollinated owing to the projection of the stigma.
The capsule splits up transversely allowing the seeds to fall out around the parent plant.
The second Latin name refers to its slender trailing or creeping stems. It is known by the name of Bog Pimpernel and Moneywort. It is a pretty flower and quite worthy of a place in our rock-gardens and bog-pools.
Essential Specific Characters: 206. Anagallis tenella, Murr. - Stem procumbent, leaves round, shortly stalked, ovate, not dotted, flowers pink, in the axils, solitary, filaments united below, corolla infundibuliform.