Brachiaria decumbens is a high-yielding, vigorous trailing perennial grass. It has a dense root-system with many bunched, quickly growing roots that go as deep as 2 m in the soil layers (Husson et al., 2008). Signal grass has a prostrate or decumbent habit, up to 60 cm high. Its flowering stems can however be up to 100-150 cm in height (Cook et al., 2005; Loch, 1977). Signal grass roots from the nodes of the stolons. The leaves are short, 4-14 (-25) cm long x 8-12 mm wide, hairy and dark green in colour (Cook et al., 2005; Bogdan , 1977). The inflorescence is a panicle with 2-7 slightly curved, 2-5 cm long racemes. The racemes are almost at right-angles to the axis (Cook et al., 2005). The spikelets are hairy, 4-5 mm long and borne in 2 rows along the rachis (Cook et al., 2005; Loch, 1977. The weight of 1000 seeds is 3.57 g (Cook et al., 2005).
Brachiaria decumbens is closely related and intergrades with B. brizantha (Cook et al., 2005). It mainly differs in its habit which is more decumbent and form a denser cover (Cook et al., 2005).
Brachiaria decumbens is the most cultivated species of the genus Brachiaria. Unlike Congo grass, it has no or very few diseases (Loch, 1977). It is a high-yielding forage that forms low leafy herbage and is mainly used as permanent pasture. It is palatable to cattle and withstands heavy grazing (Cook et al., 2005; Loch, 1977). Signal grass can be grazed, cut to be fed fresh or to be made into hay. Signal grass is also used as a cover crop and in the control of weeds (Cook et al., 2005).