Centaurium erythraea aka Centaury

Centaurium erythraea, or common centaury, belongs to the gentian family, Gentianaceae. Its native range spans Europe, including Britain and Ireland. It also reaches southwest Siberia, Iran, Yemen, Morocco and the Azores. This plant grows in temperate regions. Other names include bitter herb, bloodwort and earth gall. It grows in open woods, meadows and dry grassland. Chalk grassland and sand dunes also provide homes for it.

Common centaury is a biennial, though some plants are annuals. It forms a rosette of leaves at ground level. The plant has no hairs, and its oval leaves show veins. Its foliage is deciduous, and its growth has a bushy form. Garden plants reach about 0.3–1.6 feet [0.1–0.5 metres] tall. They spread up to about 0.3 feet [0.1 metres] wide. The RHS gives one to two years to reach full size.

Pale pink flowers appear from June through September. Each flower has a tube that opens into five lobes. Flower clusters form at stem tips and on side shoots. The long flowering season suits a wildflower meadow. The RHS also suggests this plant for wildlife gardens. Plants For A Future lists meadow sites and woodland edges. These uses fit its small size and grassland habitat.

The RHS recommends full sun and a sheltered site. Suitable soils include chalk, loam and sand, with neutral or alkaline pH. Its habitat notes stress dry ground or soil that drains well. Yet its growing table lists poor drainage, so moisture guidance conflicts. The RHS assigns it a UK hardiness rating of H4. This covers winter lows of about −10 to −5°C. Grow new plants from seed; no pruning is needed. The RHS reports few problems with pests or disease.

The herb adds a bitter taste to liqueurs, including vermouth. Plants For A Future gives its food use a low rating. It also records herbal use for appetite and digestion. Such uses do not establish that taking it is safe. Reported side effects include mild stomach pain and cramps. People with peptic ulcers should not take it. Safety during pregnancy and breastfeeding has not been established. Its flowers also yield a lasting yellow-green dye. These uses are distinct from its role as a garden wildflower.