Cyperus longus aka Sweet Cyperus

Cyperus longus, or sweet galingale, belongs to the sedge family, Cyperaceae. This grass-like perennial is native to Britain and the Mediterranean region. Its wider range reaches across Eurasia and much of Africa. It grows in marshes and along ponds, streams, canals and ditches. Useful Tropical Plants reports a stable population and Least Concern status.

Garden plants reach about 3.3–4.9 feet [1–1.5 metres] tall and wide. Other accounts describe shorter plants, around 2.6–3.3 feet [0.8–1 metre] tall. Short, thick rhizomes give rise to clusters of upright culms. The plant forms spreading clumps and grows fast. Its narrow, glossy leaves arch outwards and have rough edges. Leaves reach about 0.03 feet [0.01 metres] wide. The foliage may stay green all year or be partly evergreen. Small flower clusters appear in summer, with olive-green to brown tones. Each cluster holds narrow, flattened spikelets.

Grow this sedge in sun or light shade. It needs soil that holds moisture and does not dry out. Sandy loam suits it, but clay and other garden soils also work. It accepts acid, neutral and alkaline soil. It can grow beside ponds or in bog gardens. Shallow water up to 1 foot [0.3 metres] deep also suits it. The RHS rates its hardiness as H6. Plants For A Future lists USDA zones 6–9. Garden plants take around two to five years to reach full size.

Its clumped form suits wildlife gardens and large patio containers. A container can help limit the spread of its roots. The RHS warns that roots can spread invasively in suitable sites. This deserves attention even though Plants For A Future lists no weed potential. The RHS reports few usual pest or disease problems. Divide plants or raise them from seed to make more. In autumn, cut old leaves just above the water level.

People use the tuber as a spice in soups and sweets. It also flavours pies, according to Plants For A Future. Leaves supply material for baskets, hats and mats. Plant fibre also serves in paper making. Roots and stems have a violet-like scent used in perfume. Drying and ageing the root strengthens its scent. Older medicinal uses included an aromatic tonic and stomach remedy. Safety reports conflict: Plants For A Future lists no known hazards. Useful Tropical Plants cites reports of poisonous juice that can burn skin. These reports do not support treating the whole plant as harmless.