- Family: Pink Family – Caryophyllaceae
- Growing form: Perennial herb.
- Height: 20–80 cm (8–32 in.). With many stems, stem ascending–erect, glabrous.
- Flower: Corolla regular (actinomorphic)–slightly zygomorphic, white, approx. 2–3 cm (0.8–1.2 in.) broad; petals 5, usually deeply 2-lobed (sometimes shallowly lobed; var. littoralis). Corona unclear. Calyx fused, oval, 5-lobed, net-veined, glabrous. Stamens 10. Gynoecium syncarpous, with 3 styles. Inflorescence usually 20–50-flowered (sometimes flowers only 3–15; var. littoralis); flowers nodding, uppermost subtending bracts membranous.
- Leaves: Opposite, basal leaves stalked, stem leaves stalkless. Basal leaf blades broadly elliptic, stem leaves’ ovately elliptic–broadly elliptic (sometimes narrowly ovate–almost linear and thickish; var. littoralis), glabrous, wax-covered, bluish green.
- Fruit: Spherical, thick-walled, yellowish, seed capsule with 6 erect teeth, 8–9 mm long capsule.
- Habitat: Hillside meadows, meadows, yards, cultivated lawns, fields, banks, roadsides, wasteland, seashores and cracks in waterside rocks.
- Flowering time: June–August.
Bladder campion’s eye-catching oval calyx is like an angler’s float, and it bursts open if the mouth is closed and the oval part is pressed between one’s fingers.
Bladder campion’s most typical habitats are dryish meadows, banks, wasteland and lawns. It protects itself from drying out with a bluish green covering of wax, and its roots reach down deep into the ground. The layer of air inside the calyx insulates the flower’s more delicate inner parts from heat. The flower’s petals can lose their water content during the day and wilt, but in the evening they return to normal and start to secrete a pleasant, clove-like fragrance. Bladder campion is visited by night butterflies, but its nectar also attracts small beetles, flower flies and bees.
Bladder campion (var. vulgaris) spread with people in ancient times all over inland Finland, and a coastal form, (var. littoralis), whose stems are ascending and usually slightly smaller, and which has slightly fleshy leaves, less flowers and only slightly lobed flowers, grows on gravel, shingle and stony shores. Apart from the south coast of Finland it grows on the Estonian and Russian sides of the Baltic Sea. Around the Gulf of Bothnia its place is taken by sea campion (S. uniflora), which doesn’t grow at all around the Gulf of Finland. The species meet on the south-western archipelago. Sea campion grows lower and is more limp than var. littoralis, its flowers are solitary or in pairs, and it has clear corona scales between its petals.