- Name also: Seaside Sandplant (USA, Canada)
- Family: Pink Family – Caryophyllaceae
- Growing form: Perennial herb. With subterraneous runners.
- Height: 5–15 cm (2–6 in.). Runners up to 30 cm (12 in.) long. Stem fleshy. Forming mat-like stands.
- Flower: Usually dioecious (pistillate and staminate flowers on different plants). Corolla regular (actinomorphic), white, 6–10 mm (0.24–0.4 in.) broad; petals 5, staminate flower 3.5–6 mm (0.14–0.24 in.) long and longer than calyx, pistillate flower 1.5–4 mm (0.06–0.16 in.) long and shorter than calyx. Sepals 5, green. Stamens several. Gynoecium syncarpous, with 3 styles. Inflorescence a 1–6-flowered terminal cyme, solitary flowers axillary.
- Leaves: Opposite, stalkless. Blade ovate–elliptic, tapered, with entire margins, glabrous, fleshy, dark–lime green.
- Fruit: Spherical, 3-valved, 6–10 mm (0.24–0.4 in.) long capsule.
- Habitat: Sandy, stony and gravelly areas by seashores.
- Flowering time: June–August.
Sea sandwort’s fleshy and shiny leaves can bring genus Sedum to mind, but the species belongs to the Pink family. These adaptations have happened independently of each other in different families to solve the same problem – water conservation. Sea sandwort is a salt-loving plant (halophyte) which is not afraid of being splashed by sea water. Even being covered by water or sand can’t put it down because it has adapted to grow amidst the turbulence of the coast.
Sea sandwort grows on rocky and shingly shores, winding through cracks between rocks, but its own kingdom is sandy shores. Along with sea pea and lyme grass it is one of Finland’s most important coastal pioneer plants, keeping the sand in its place. Sea sandwort’s long-branched rootstock grows quickly under the sand and finely-branched shoot roots anchor the plant firmly in the sand. The rootstock produces an abundance of buds from which new shoots grow. Some of them hold their fire, however, so that a plant that is buried in a storm can send new shoots back up to the surface without having to produce new shoots.
Sea sandwort stabilises and fertilizes the land it is growing on, thereby helping more demanding sea-shore plants. In time it changes the conditions in a way that they meet more plants’ demands and it eventually finds itself in retreat from the ever-increasing competition. The species has also had to avoid people too sometimes when they have turned its habitat into a swimming beach. The species is most common around the Bay of Bothnia.
Sea sandwort’s flowers are usually unisexual, i.e. the stamens and pistils are on different plants. Sometimes bisexual flowers turn up, but they are functionally unisexual because either the stamens don’t produce any pollen or the pistils don’t work. The flowers are pollinated by insects and have an abundance of nectar – it is probably not however impossible that the pollen can be wind-borne, as there is often a strong breeze in its habitat blowing around the fine sand. Sea sandwort spreads efficiently through its rootstock, and a wide carpet can be clones of the same plant.