- Name also: Bladder Campion (USA)
- Family: Pink Family – Caryophyllaceae
- Growing form: Annual, biennial or short-lived perennial herb.
- Height: 30–60 cm (12–25 in.). Stem erect, branched, short-haired, upper part with glandular hairs, but not sticky.
- Flower: Plant dioecious (pistillate and staminate flowers on different plants). Corolla regular (actinomorphic), white, approx. 3–4 cm (1.2–1.6 in.) broad; petals 5, tip quite deeply 2-lobed. Corolla mouth with lobed corona. Calyx fused, 5-lobed, staminate flower narrow, pistillate flower oval. Stamens 10. Gynoecium syncarpous, with 5 styles. Inflorescence many-flowered. Flowers opening in evening, with weak fragrance.
- Leaves: Opposite, basal leaves stalked, upper stalkless. Blade ovate–ovately lanceolate, with entire margins, hairy, dark green.
- Fruit: Elliptic, yellowish brown, 15–22 mm (0.6–0.88 in.) long capsule.
- Habitat: Fields and roadsides, lawns, walls around inhabited areas, harbours and wasteland.
- Flowering time: June–August.
White campion is a native Eurasian species which has spread to Finland with imported grain and hayseed and in Russian soldiers’ provisions. Its origins can still be seen in its habitat: it is common only in the eastern part of the southern half of the country and is rarer elsewhere. On a local level the densest concentrations are often around old forts, posts and other places that supported the czar’s military network. Stands that grow around hospitals and graveyards also probably have the same origin. White campion has arrived in Finland in recent decades and is now heading mainly west. It has settled in quite well in Finland, so it is difficult to notice any increase.
White campion cross-breeds with red campion (S. dioica) to produce a delicately pink-flowered hybrid. In its native areas the species’ habitats are separate, but in Finland they often appear together in environments that are influenced by people. Their flowering and pollination times overlap slightly. White campion’s petals are closed during the day and the flower seems quite exhausted: it opens, increases its nectar production and becomes more strongly fragrant in the evening to attract night butterflies. Efficient white campion pollinators are night butterflies and small hawk moths. Large hawk moths suck the nectar through their long proboscises without touching the stamens or pistils – from the plant’s point of view they are only stealing its nectar.
White campion is, like red campion, dioecious: its staminate and pistillate flowers are on different plants and it must therefore be cross-pollinated. The staminate flowers fall away soon after flowering, but the pistillate flower’s calyx enlarges to protect the developing seeds. Up to one hundred seeds develop inside the capsule and then fly out when the wind or some passer-by shakes the plant. White campion is a good ornamental for the garden and yard, and when it is transplanted to these locations it usually only becomes stronger and more impressive. It is always quite short-lived, but it often self-seeds close by.