- Name also: European bur-reed
- Family: Cattail Family – Typhaceae
(formerly Bur-reed Family – Sparganiaceae)
- Growing form: Perennial herb, water plant, rootstock creeping.
- Height: 20–70 cm (8–28 in.). Stem erect, unbranched, glabrous.
- Flower: Flowers unisexual. Spherical clusters of stamens (4–8) above, filament 6–8 mm (0.24–0.32 in.), anther 1–1.5 mm (0.04–0.06 in.), clusters of pistils (2–5) below, a single carpel, 2 mm (0.08 in.) long. Tepals light brown, translucent. Inflorescence long, flowers unbranched.
- Leaves: Alternate, erect, long, linear, 3-edged, keel-backed, 5–12 mm (0.2–0.48 in.) broad. Floating leaves up to 2 m (80 in.) long.
- Fruit: Long-tipped (4 mm (0.16 in.), elliptic, light brown, shiny stone fruit, 4–5 mm (0.16–0.2 in.) long excluding tip. Stone fruit forms a 10–15 mm (0.4–0.6 in.) wide spine-ball.
- Habitat: Ditches, puddles, rich, muddy-bottomed lakes and rivers.
- Flowering time: July–August.
- Endangerment: Branched bur-reed is classified as near threatened.
Genus Bur-reed contains slightly over 20 species, of which 7 grow in Finland. Unbranched bur-reed is the most common of these. The others are branched bur-reed (simplestem bur-reed, S. erectum), S. gramineum, floating bur-reed (narrowleaf bur-reed, S. angustifolium), clustered bur-reed (S. glomeratum), least bur-reed (small bur-reed, S. natans) and northern bur-reed (S. hyperboreum). Their names give some clues to the ways that they differ from one another.
Bur-reeds formerly comprised a family of their own, Sparganiaceae, but this is nowadays part of the Cattail family. They are monocotyledons and belong to the order Poales, which includes hays, sedges and rushes (and which are dealt with on this web site in a category of their own which is still under construction). The world’s largest monocotyledon family is the orchids (Orchidaceae). Other monocotyledons that grow in Finland and that are included in this web site include among others Liliaceae (lilies), Iridaceae (irises), Melanthiaceae (wake robins), Asparagaceae (lilies-of-the-vallies), Amaryllidaceae (garlics and many others), Araceae (arums), Alismataceae (water-plantains), Hydrocharitaceae (frogbits) and Juncaginaceae (arrowgrasses).