This section is from the book "British Wild Flowers - In Their Natural Haunts Vol2-4", by A. R. Horwood. Also available from Amazon: A British Wild Flowers In Their Natural Haunts.
This plant is not found in any ancient deposits. In the North Temperate Zone to-day it is found in Europe, South of Belgium, N. Africa, W. Asia, and the S. Temperate regions. In Britain it is found around the entire coast, except in E. Sussex, Denbigh, S. Lines, Northumberland, Berwick, Fife, as far as Islay, but on the west to the southward, and in the Hebrides. It is native in Ireland and the Channel Islands.
The Seaside Bindweed is a strictly maritime plant, a salt-lover, and dry-soil type, growing on sandy coasts, where it obtains plenty of salt, and where dry conditions are ensured. It is associated with Sea Kale, Sea Rocket, Sea Milkwort, Samphire, and numerous other sand-loving marine plants.
This seaside species differs from other bindweeds in not having a climbing but a trailing stem. Its stem is prostrate, then ascending, short, slender, and only rarely twining. The leaves are kidney-shaped or heart-shaped, fleshy, with rounded lobes. The stems are often much below the surface in the sand.
The flowers are flesh-coloured, borne on 1-flowered flower-stalks, square, with membranous angles. The bracts or leaflike organs are less than the calyx, and egg-shaped. The flowers are large, axillary, and the pink corolla is marked with longitudinal yellowish or red streaks. The capsule is large.
Seaside Bindweed is at most I ft. high. It is usually in flower in June and July, and is a perennial plant, which is increased very freely by division of the roots.
The flowers are complete and the plant is gynodioecious. The flowers are as in C. arvensis, but they possess two bracts enclosing the calyx, and the stigma is broad. The stamens and pistil vary in length.
Photo. Messrs. Flatters & Garnett - Seaside Bindweed (Calystegia Soldanella, Br.)
Being a maritime plant it is not visited to any extent by insects. In C. arvensis, which is pollinated like the Seaside Bindweed, the flowers are scented, opening between 7 a.m. and 10 p.m., closing at night and during rain. There is honey at the base of the tube. The stamens lie close to the tube and have enlarged bases. At their edge the anther-stalks are interwoven by stiff projections. The anthers open outwards and lie below the stigmas, which an insect touches first. The corolla may have a red band, the flower may be small, and there may be a pistillate type with short stamens and undeveloped anthers. The capsule splits open when ripe, and is filled with black seeds, which are dispersed around the parent plant being aided partly by the wind.
The plant is a salt-lover, and grows in saline soil which is largely sand soil also.
A fungus, Thecaphora hyalina, attacks the leaves.
Calystegia is from two Greek words denoting calyx and cover, reference being to the two large bracts of the calyx. Soldanella, Dodonaeus, is possibly derived from the Latin soldo, an Italian coin, because of its rounded leaves.
Sea Bells, Sea Bindweed, Sea Cawle, Sea Coale, Sea Cole, Sea Colewort, Sea Foalfoot, Scottish Scurvy Grass, Sea Withwind, are names it has been given. Sea Foalfoot is bestowed on it because of the shape of the leaves, and Scottish Scurvy Grass because, as Gerard says, "They use it instead of true scurvy grass (Cochlearia officinalis)". The plant is an acrid purgative.
Essential Specific Characters: 221. Calystegia Soldanella, Br. - Stem prostrate, short, leaves fleshy, reniform, flowers pink, with yellow bands, bracts shorter than the calyx, on winged, square stalks.