Weed Identification

Australia > > Spiny Rush

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) 24 mm wide. Inflorescence 413 cm long, consisting of clusters of 16 flowers; 1 or 2 leaf-like bracts 425 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 1.22 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 46 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 2.53 mm long and seeds 0.51 mm long.

Inflorescences & spine-tipped bracts, Kerang, Vic, Oct

Notes: Widespread in damp places and infrequently inundated watercourses on the coast and inland. The sharp spines, that project at many angles, make it especially dangerous for children.


    Noxious Weeds of Australia.W. Parsons and E. Cuthbertson, 1992, pages 8184. Waterplants in Australia. G. Sainty and S. Jacobs, 4th edition, 2003, pages 168169.

Roots & base of plants

Capsules & tailed seeds

Mason Park Saltmarsh, NSW, Aug

This weed has been included in the WEEDeck field guide as card W22

More information about WEEDeck is available from Sainty & Associates Pty. Ltd.


Australia > > Spiny Rush


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