Eriophorum gracile aka Slender Cottongrass

Eriophorum gracile is a perennial in the sedge family, Cyperaceae. Its common names include slender cottongrass and cotton grass. It comes from central and northern Europe, including Britain. The RHS also records it as native to Britain and Ireland. In the wild, it grows in wet, acid bogs. Plants For A Future describes it as rare and local there. It reaches about 1.6 feet [0.5 metres] in height.

Flowers appear from June to July, and wind carries the pollen. Each plant bears both male and female flowers. The seeds ripen from July to August and bear cottony hairs. These hairs have several uses beyond their role on the plant. People use them for candle wicks, pillow filling, and paper. They also serve as tinder for starting fires. The supplied species evidence gives no further leaf or stem details.

This plant needs wet ground with an acid soil. A bog garden or pond edge can meet those needs. It can also grow in water rather than just damp soil. It accepts sandy soil, loam, and clay, including heavy clay. Both mildly acid and very acid soils suit it. Grow it in full sun or light shade. Its need for wet, acid ground limits suitable garden sites. The evidence gives no hardiness zone or firm cold limit.

Plants For A Future warns that it can spread invasively in cultivation. Its separate weed entry, however, does not flag weed potential. These entries leave the degree of garden spread unclear. Seed and division both offer ways to raise more plants. Sow seed in spring, with moist soil and light shade. At 15°C, germination takes about two to six weeks. Pots standing in a water tray help keep compost moist. Divide plants in spring or autumn, then replant the pieces. Young plants raised in pots can go outside in summer.

Young stem bases and roots have recorded food uses. Both can be eaten raw or cooked, according to Plants For A Future. Remove the dark outer covering from the roots first. That source gives the plant a modest food-use rating. It reports no known hazards, but this does not prove safety. It lists no known medicinal uses. The supplied evidence names no pests or diseases affecting this species.