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.
The Sea Purslane is a sine qua non, as it were, of the flora that one meets with on most sea-coasts. It grows on every sandy beach, being a sand plant like the majority of the species of this group (hence the generic name), and is a salt-lover and one of the strand plants, accompanied usually by such plants as Sea Rocket, Saltwort, Sea Milkwort, Sand Sedge, Marram Grass, and other plants.
Photo. Messrs. Flatters & Garnett - Sea Purslane (Arenaria peploides, L.)
It has a creeping habit, the so-called roots being really rhizomes. The stem is prostrate, then ascending, fleshy, forked, and the branches are suberect. The leaves are lance-shaped, stalkless, arranged in opposite rows, egg-shaped, acute, bent backwards, close, and single-nerved, with the margins distinct. The whole plant is smooth, shiny, and dark green, like a Stonecrop or Sea Milkwort.
The flowers are white, solitary, axillary, the petals are inversely egg-shaped, the sepals blunt, single-veined, and shorter than the petals in the male, longer in the female flowers. The long and short stamens alternate. The capsule is rounded, the seeds are inversely egg-shaped, large, and not numerous.
The height of this plant rarely exceeds 3 in. It is in flower from May till August. The perennial stems can be propagated by division.
The flowers are polygamous. The disk is glandular. There are 3-5 styles, and the flower is able to self-pollinate itself in the absence of insects, which do not visit it commonly, the species being a maritime with inconspicuous flowers.
The seeds are dispersed by the agency of the plant's own mechanism. The capsules break up along the valves when ripe and allow the small seeds to fall around the parent plant, which is usually found to grow in scattered clumps.
A fungus, Cystopus lepigoni, attacks Arenaria.
Heliothis peltiger (the Bordered Straw Moth) feeds on species of Arenaria also, and the beetles Malachius marginellus and Cassida nobilis.
Sea Purslane is a sand-lover and requires a sand soil, and as a salt-lover saline soil.
Arenaria, Linnaeus, is derived from the Latin arena, sand, and peploides is from its resemblance to peplion, a purslane.
The Sea Purslane is called Sea Chickweed and Sea Sandwort.
It was thought to inspire love. Formerly it was occasionally pickled, like samphire, for which its fleshy foliage is suited. It was fermented in Ireland, and eaten as sauerkraut is in Germany.
The flower is very variable in the number of the stamens, a feature of the group.
Essential Specific Characters: 57. Arenaria peploides, L. - Stem fleshy, creeping, forked, leaves in 4 rows, ovate, sessile, smooth, dark-green, flowers small, white, petals obovate, exceeding the sepals, from the angles of the stem.