Digitaria didactyla

Queensland blue couch


Digitaria didactyla

Willd. 1809

pronounced: dij-ih-TARE-ee-uh did-ACT-ty-luh

(Poaceae — the grass family)


common name: Queensland blue couch

Digitaria comes from the Latin word digitus, a finger (or toe), referring to the seed head of the Fingergrass genus; didactyla is from the Greek διδακτυλος (didaktylos), having 2 fingers. The species has at least 2 racemes, but there are often 3 or 4.

This is one of the favourite lawn grasses in this part of the world, and, indeed, in many parts of the tropics. With frequent mowing, it forms a soft, springy turf, and is quite effective in crowding out weeds and other grasses, even buffalo grass.

The grass is native to Malawi, Mozambique, South Africa, Swaziland, Mauritius and Reunion. It is now widespread throughout the tropics and subtropics. It has a fairly wide tolerance of soil types, but has a definite preference for lighter soil, and is very common on granite sands. This makes it an ideal lawn grass for Magnetic Island, particularly where the lawn is irrigated. It prefers an annual rainfall range of 900–1,800 mm, and will survive seasonal dry conditions by losing all its leaf, the rhizomes surviving underground. On light soils, it responds almost instantly to good rainfall. It can also tolerate short-term flooding and water-logging.

Queensland Blue Couch is a small, strongly stoloniferous perennial grass, rooting and branching from the nodes, with bluish-green coloured leaves. The leaf-sheath is densely to sparsely pilose, the ligule 1 – 1.5 mm long, the blade 1 – 3 mm wide, usually glabrous. The sward can grow to 20 cm high if not grazed or mown. The inflorescence consists of 2 – 4 racemes,  2 – 7 cm long, the spikelets appressed, rather crowded and overlapping, paired on unequal pedicels, the longer pedicel to 2 mm long, the other very short. The spikelets are 2 – 3 mm long.

Caterpillars of the Dusky Knight butterfly Ypthima arctous feed on this grass.


Photographs taken 2010, Picnic Bay
Page last updated 11th December 2018