Brachiaria decumbens is closely related to Brachiaria brizantha. It is distinguished from Brachiaria brizantha by its stoloniferous habit, flat raceme rhachis and herbaceous superior glume and inferior lemma, but the two species intergrade and some of the cultivated forms are difficult to assign. Glume and lemma texture seem to be the best and decumbent habit the least reliable diagnostic characters[].
The genera Brachiaria and Urochloa are closely related, and the two are united by some authors. See Veldkamp, Taxon 45 (1986) 319. However, this unification is not accepted by all authors - see Flora of China Vol 22 pp520-523 2006. We are following the treatment in the Flora of China and the Kew 'World Checklist of Selected Plant Families', and treating the two genera as distinct[].
Brachiaria and Urochloa are distinguished mainly by habit, Urochloa having rather more flattened, cuspidate spikelets enclosing a pronounced mucro from the upper lemma. The different spikelet orientation is also characteristic, though not obvious when the spikelets are paired. In Urochloa the lower glume faces outward, whereas in Brachiaria it lies against the rachis[]..

Common Name: Signal Grass

General Information

Brachiaria decumbens is an evergreen grass forming a clump of erect culms 30 - 150cm tall from a long, stoloniferous base. The culms root at their lower nodes, forming a dense mat of growth[].
The plant is used to cover the ground and prevent soil erosion.

Known Hazards

A widespread, but sporadic, toxicity syndrome associated with Brachiaria decumbens is hepatogenous photosensitization. The exact causes are not understood, but some researchers believe that an infestation of the grass by the saprophytic fungus Pithomyces chatarum, which produces spores thought to contain the toxin sporidesmin[].

Botanical References

Range

Tropical Africa - DR Congo, Uganda, Burundi, Rwanda, Kenya, Tanzania

Habitat

A weed in Australia, growing in tropical heaths, tropical and subtropical rain forests, tropical and subtropical wet sclerophyll forests, and tropical and subtropical sub-humid woodlands[].

Properties

Weed Potential	Yes
Other Uses Rating
Habit	Evergreen Perennial
Height	1.00 m
Pollinators	Wind
Cultivation Status	Cultivated

Cultivation Details

Brachiaria decumbens is a plant of the tropical zone, where it is found between latitudes 27° north and south, at elevations up to 1,800 metres. It succeeds in areas will all year rainfall and also where a dry season is up to 5 months long. It grows best in areas where annual daytime temperatures are within the range 25 - 35°c, but can tolerate 19- 38°c[]. It is not very tolerant of frost, often being killed at 0°c[]. It prefers a mean annual rainfall in the range 1,500 - 1,800mm, but tolerates 900 - 2,400mm[].
Grows best in a sunny position, but tolerant of light shade[]. Succeeds in a wide range of well-drained soils, tolerating, poor shallow soils[]. It has excellent tolerance to aluminium in the soil[]. Prefers a pH in the range 5 - 6, tolerating 4.5 - 6.5[]. Established plants have a good tolerance of drought[].
The plant can become a weed but is easily controlled by ploughing it out[].

Edible Uses

None known

Medicinal

None known

Agroforestry Uses:

A valuable grass for erosion control as it covers the ground well, withstands heavy grazing and establishes on poor and rocky soils[, ]. It is important because of its high productivity under intensive use, its tolerance of low fertility and relative freedom from pests and diseases[]. Plants can cover the ground within 90 days from seed[].

Other Uses

None known

Propagation

Seed - should be sown no deeper than 10mm and rolling is recommended after sowing. Best results are obtained when seed is sown during the wet season[]. The seed needs after-ripening for 10 - 12 months to break dormancy. Treating the seed for 10 - 15 minutes with commercial sulphuric acid will improve germination of recently harvested seed from nought to 33%). Seedling vigour is excellent[]
Division of culms and root pieces[].

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