Sporobolus virginicus  (L.) Kunth 1829

pronounced: spor-ROB-oh-luss vur-JIN-ih-kuss

(Poaceae – the grass family)

common name: Marine Couch

Sporobolus sporobolus virginicusnew growthsporobolus virginicusmarine couchis derived from the Greek σπορα (spora), seed sown, and βολος (bolos), a throwing, alluding, presumably, to the way the seed is forcibly released in some species of this grass; virginicus is botanical Latin for ‘of or from Virginia (USA)’.

This grass is known by numerous common names, including Sand Couch, Coastal Rat-tail Grass, Salt Couch Grass, Saltwater Couch and Nioaka. It is a perennial non-bunching coastal tussock grass with a wide distribution, from 10 – 50 cm tall, with green or purple flowers. It produces asexually by use of both stolons and rhizomes. It grows in Australia, New Zealand, the Pacific islands, the Caribbean, Africa, India, China and Indonesia. It grows in every Australian State. In Queensland it appears both on the coast and on inland saline soils, although inland records often probably refer to the closely related Sporobolus mitchellii (Rat’s Tail Couch) which is less tolerant to waterlogging and salinity. These two grasses  can be an important grazing plant for cattle during the dry season in northern Australia.

Its leaves are alternate, up to 17 cm long, and are in 2 ranks on either side of the stem. The stems can be either vertical and horizontal. The ligule is a ciliate rim with tiny hairs less than 0.25 mm long, each end often with rigid hairs up to 2 mm long; the blade is rolled, to 3 mm wide, ribbed and glabrous; the sheath is glabrous, the upper margin sometimes scattered with rigid tubercle-based hairs about 0.5 mm long. The plant flowers throughout the year, and flower heads can grow up to 10 cm long. The inflorescence is spicate, 3 – 13 cm long by up to 1 cm wide; the rachis is flattened or angled, ribbed, and glabrous; the spikelets are 2 – 4 mm long, with one floret; the pedicels are 1 – 4 mm long, and scabrous; the glumes are hyaline, smooth and glabrous. The plant does not always set viable seed.

Marine couch grows in upper tidal, inter-tidal and some inland areas. It prefers sandy soils, and tends to form dense, low mats of vegetation. The plants photographed were growing in the tidal salt flats at Cockle Bay. When this grass is transplanted as a turf, it is an excellent plant for the rehabilitation of saline wetlands.

Photographs taken at Cockle Bay 2012

Page last updated 18th February 2017

 

 

 

 

 

 

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