Spiny Rush

Juncus acutus

Alternative Name(s): Sharp Rush.

Family: Juncaceae.

Form: Water plant

Origin: Native of Europe, Africa and North America.

Flowers/Seedhead: Flowering stems (culms) 2–4 mm wide. Inflorescence 4–13 cm long, consisting of clusters of 1–6 flowers; 1 or 2 leaf-like bracts 4–25 cm long at base of inflorescence. Stamens 6. Flowers throughout year but mostly spring and summer.

Description: Shortly rhizomatous, tussocky perennial rush to 1.6 m high. Flowering stems and stem-like leaves arise from the base at varying angles giving the whole plant a characteristic globe shape. Fruit an ovoid 3-celled brown capsule. Seeds 1.2–2 mm long, brown.

Distinguishing features: Distinguished by pith-filled stems and leaves; leaves similar to flower stems and other leaves forming a basal sheath (cataphyll) around the flower stem; leaves and bracts terminate in a stiff sharp point; capsules 4–6 mm long; seed with a tail at each end.

Dispersal: Spread by seed. Much of the spread appears to be by seedcontaminated mud attached to vehicles and animals.

Confused With: Juncus kraussii a native salt marsh species that has capsules 2.5–3 mm long and seeds 0.5–1 mm long.