Urochloa platyphylla
(broadleaf signalgrass)

Preferred Scientific Name

• Urochloa platyphylla (Munro ex C. Wright) R.D. Webster

Preferred Common Name

• broadleaf signalgrass

Other Scientific Names

• Brachiaria extensa Chase
• Brachiaria platyphylla (Munro ex C. Wright) Nash
• Panicum platyphyllum Munro ex C. Wright
• Paspalum platyphyllum Griseb.
• Urochloa extensa (Chase) C.Nelson, Sutherl. & Fern.Casas

International Common Names

• English: white para grass
• Spanish: Gambutera

Local Common Names

• Trinidad and Tobago: wild para

EPPO code

• BRAPP (Brachiaria platyphylla)

• Domain: Eukaryota
•     Kingdom: Plantae
•         Phylum: Spermatophyta
•             Subphylum: Angiospermae
•                 Class: Monocotyledonae
•                     Order: Cyperales
•                         Family: Poaceae
•                             Genus: Brachiaria
•                                 Species: Urochloa platyphylla

The taxonomy of the genus Urochloa is unclear mostly due to the weaknesses of the characters used to separate Urochloa from Brachiaria (i.e., spikelet orientation and presence or absence of an upper floret). These weaknesses have been discussed by several authors including Webster (1987, 1988) and Morrone and Zuloaga (1992, 1993). Floristic studies conducted in Australia (Webster, 1987), North America (Webster, 1988; Zuloaga and Morrone, 2003), South America, Mexico and Central America (Morrone and Zuloaga, 1992, 1993) have circumscribed species of Brachiaria into Urochloa. On the other hand, Sharp and Simon (2002) maintain the name Brachiaria for all species that occur in Australia and the annual species of Brachiaria are now included in the new genus Moorochloa (Veldkamp, 2004). The taxonomic positions of these three genera still remain unclear. The species Urochloa platyphylla is also named as B. platyphylla which is still an accepted name by some authorities (USDA-ARS, 2014). 

U. platyphylla is an annual grass. Culms 25-100 cm, decumbent, rooting at the lower nodes; nodes glabrous. Sheaths glabrous or sparsely pilose; ligules 0.5-1 mm; blades 2.5-17.5 cm long, 3-13 mm wide, glabrous or sparsely pilose, bases subcordate, not clasping the stems, margins ciliate basally, with papillose-based hairs. Panicles 6-16 cm long, 2-2.5 cm wide, with 2-8 spike-like primary branches in 2 ranks; primary branches 3-8 cm, axils pubescent, axes 1.3-2.5 mm wide, flat, usually glabrous, occasionally pilose dorsally; secondary branches rarely present; pedicels shorter than the spikelets, scabrous and sparsely pilose. Spikelets 3.8-5 mm long, 2-2.5 mm wide, ovoid, bi-convex; solitary, appressed to the branches, in 2 rows. Glumes scarcely separated; lower glumes 1.2-1.8 mm, to 1/3 as long as the spikelets, obtuse, glabrous, 5(-7)-veined, not clasping the base of the spikelets; upper glumes 3.2-4.7 mm, glabrous, 7(-9)-veined; lower florets sterile; lower lemmas 3.2-4.7 mm, glabrous, 5-veined; lower paleas present; upper lemmas 2.8-3.4 mm long, 1.8-2.3 mm wide, apices incurved, broadly acute to rounded, mucronulate; anthers about 1 mm. Caryopses 1.5-2.2 mm (Wipff and Thompson, 2003). 

U. platyphylla is a widespread summer growing weed of cultivation, gardens, roadsides and disturbed places. It is highly accepted that U. platyphylla has been unintentionally introduced into new areas as a contaminant in crop-seeds. Seeds of U. platyphylla often occur as contaminants of maize-seed exported from the USA (USDA-ARS, 2014; USDA-NRCS, 2014). In Belgium it was introduced with soyabeans and birdseed and it was first reported in 1992 (Verloove and Vandenberghe, 1993).

Soil reaction

• neutral

Soil texture

• light
• medium

U. platyphylla spreads by seeds. The seeds are tiny and spilled along roadsides, agricultural land and around feedlots where they may germinate, especially if they fall or are washed into ditches or damp places. Once established, U. platyphylla can be spread by implements such as headers, in irrigation and flood water, in soil, in seeds, and in plant debris. 

U. platyphylla is an environmental and agricultural weed. This grass is very aggressive and can reduce yield in crops. B. platyphylla is a species of concern because it is more difficult to control than other weeds due to its resistance to the most common herbicides, causing great expense to producers (Chamblee et al., 1982; Gallaher et al.,1999; Alford et al., 2005; Sesto et al., 2011).

• Proved invasive outside its native range
• Abundant in its native range
• Highly adaptable to different environments
• Is a habitat generalist
• Tolerates, or benefits from, cultivation, browsing pressure, mutilation, fire etc
• Pioneering in disturbed areas
• Benefits from human association (i.e. it is a human commensal)
• Fast growing

• Ecosystem change/ habitat alteration
• Modification of hydrology
• Modification of successional patterns
• Negatively impacts agriculture
• Reduced native biodiversity

• Competition - monopolizing resources
• Herbivory/grazing/browsing
• Rapid growth

• Highly likely to be transported internationally accidentally
• Difficult to identify/detect as a commodity contaminant
• Difficult/costly to control

U. platyphylla is sometimes used as a forage for livestock (USDA-ARS, 2014).