SafePlants

Broadleaf Signalgrass and Tropical Signalgrass: A Comprehensive Overview

This page provides information on broadleaf signalgrass (Brachiaria platyphylla) and tropical signalgrass (Urochloa subquadripara, formerly Brachiaria), two grasses often considered weeds, particularly in agricultural settings.

Considerations for Pets

• Some texts mention signal grass toxicity in sheep, however this appears to be a specific case.
• Some signalgrasses are low-growing and could be attractive to animals.

Nomenclature and Taxonomy

• Broadleaf Signalgrass:
  • Scientific Name: Brachiaria platyphylla (syn. Urochloa platyphylla)
  • Synonyms: Urochloa platyphylla (Munro ex C. Wright) R.D. Webster
  • Family: Poaceae (Grass Family)
  • Classification: W107
• Tropical Signalgrass:
  • Scientific Name: Urochloa subquadripara
  • Common Name: Small flowered alexandergrass
• Other Signalgrasses:
  • Urochloa distachya
  • Urochloa decumbens (syn. Brachiaria decumbens)
  • Urochloa humidicola
  • Urochloa reptans (syn. creeping panic grass, running grass or sprawling signal grass)

Distribution and Habitat

• Broadleaf signalgrass is commonly found as a weed in agronomic crops in the southeastern United States.
• Brachiaria, or signalgrass, is native to tropical and subtropical regions of Asia, Africa, Australia, southern Europe, and the Americas.
• Tropical signalgrass is a significant weed problem in St. Augustinegrass sod production in Florida.
• Browntop Signalgrass is found in open sandy ground of the Edwards Plateau and South Texas Plains.

Morphological Characteristics

• Broadleaf signalgrass can reach up to 3 feet in height.
• Tropical signalgrass stems are typically trailing and creeping, rooting at the nodes. Leaf blades are flat, 0.3-0.5 inches wide, and up to 0.75 inches long.
• Broadleaf signalgrass has wide, hairless leaves that tend to remain erect, and a fringed membranous ligule.
• Urochloa decumbens (signal grass) is described as a long-lived grass (up to 1.5 m tall) with stems usually lying close to the ground.
• Creeping signalgrass (Urochloa humidicola) has stoloniferous culms, ascending or decumbent, 40-100 cm long, without nodal roots, or rooting at the nodes.

Ecological Role

• Signalgrasses are often considered weeds, particularly in agricultural and turfgrass settings.
• Tropical signalgrass is a troublesome weed in St. Augustinegrass sod production, increasing production costs.
• Broadleaf signalgrass can interfere with corn yield in no-tillage conditions.
• Signal grass is an aggressive tropical grass with the ability to grow well in a wide range of soil and moisture conditions.

Interactions with Other Organisms

• Pinto forage peanut, centro, and creeping vigna can form long-term pastures with signal grass under intensive grazing.
• Johnsongrass, Yellow Foxtail, and Broadleaf Signalgrass can act as new hosts for certain species of Bipolaris, Curvularia, and Exserohilum that are pathogenic to Bermudagrass.

Common Names

• Signalgrasses: Also referred to as Alexandergrass
• Brachiaria decumbens:
  • English: Surinam grass, signal grass, Kenya sheep grass, sheep grass
  • Spanish: braquiaria decumbens, pasto alambre, pasto braquiaria, pasto chontalpo
  • German: Surinamgras