- Name also: Dane’s Blood (USA)
- Family: Bellflower Family – Campanulaceae
- Growing form: Perennial herb. Rootstock short, thick.
- Height: 20–80 cm (8–30 in.). Stem unbranched, slightly angular, lower part almost round, sparsely haired–almost glabrous, often dark reddish brown.
- Flower: Corolla campanulate (bell-shaped), 5-lobed halfway, fused, 16–30 mm (0.65–1.2 in.) long, dark purple–blue or occasionally white. Calyx fused, 5-lobed, lobes long-tapered, sharp, with toothed margins, hairy. Stamens 5. Pistil of 3 fused carpels, shorter than corolla. Inflorescence a dense umbel terminating stem and axillary in upper branches.
- Leaves: Basal leaves long-stalked, ovate–long ovate, often with cordate base, usually withered by flowering time. Stalk narrowly winged at most. Stem leaves alternate, lowest like basal leaves, upper stalkless, semi-amplexicaul, ovate–lanceolate. Blade finely toothed, both sides hairy.
- Fruit: Roundly conical, strongly veined, capsule opening from base.
- Habitat: Coppices, meadow slopes, forest margins, banks, waste ground, dry meadows. Also an ornamental.
- Flowering time: June–August.
Clustered bellflower is clearly most common in the south-east, and is thus most common around Finland’s Lake District. The border of its habitat is quite sharp, although it sometimes grows elsewhere in the country beside highways and in densely populated areas. Large and many-flowered plants in particular have been quite commonly transplanted into gardens. Apart from the wild population, garden varieties have also been developed. The species clearly exploits human activity and occasionally grows wild. Clustered bellflower has been classed as an old follower of people, and sometimes as an alien species.
Although clustered bellflower is a highly diverse species, it is easy to tell apart from other bellflowers due to its dense, umbellate inflorescence. The easiest species to confuse it with is bristly bellflower (C. cervicaria), which is bristle-haired and usually has a clearly winged leaf-stalk. The flower also has other differentiating characteristics: its sepals are more blunt-tipped, its corolla is pale blue, and its long pistil protrudes from the corolla.