Hymenachne amplexicaulis

West Indian marsh grass

Nonnative to FloridaFISC Category 1 Invasive
Species Overview

Native to: West Indies, tropical Central and South America, 

West Indian marsh grass is occasionally found growing in wet pastures from the central peninsula to Collier county. It is native to the West Indies and blooms in the fall (Wunderlin, 2003).

Description
  • Family: Poaceae
  • Habit: : Robust perennial grass from stolons; stems floating, creeping, or ascending to 1 m (3 ft) or more in height, sparingly branched, rooting at the lower nodes; stems pithy, not hollow
  • Leaves: blades flat, to 35 cm (14 in) long and to 4 cm (1.6 in) wide, cordate at the base and clasping the stem; glabrous but with long hairs on lower margins
  • Flowers: Anthers 3; 1.1-1.2 mm long
  • Infloresence: terminal panicle, dense and spike-like, about 8 mm (0.3 in) wide and to 50 cm (20 in) long; spikelets short stalked, 3.3-4.3 mm long, scabrous on the veins, often opened slightly at the apex
  • Fruit: spike-like, densely flowered panicle, to 26 cm (10 in) long and ~1 cm (0.4 in) wide; spikelets short-stalked
  • Seeds: 3-4 mm
  • Distribution in Florida: central and south

 

West Indian marsh grass may be confused with the native American cupscale (Sacciolepis striata) which has a similar inflorescence. However, Hymenachne stems contain white pith, whereas most grass stems are hollow.

Impacts

West Indian marsh grass has been found to be displacing native maidencane (Panicum hemitomon) communities in central and south Florida. It forms dense colonies and has become increasingly difficult to controla, especially long drainage canals of south central Florida.

West Indian marsh grass is not recommended by UF/IFASThe UF/IFAS Assessment lists as West Indian marsh grass as invasive/no use in all parts of Florida. FLEPPC lists it as a Category l invasive species due to its ability to invade and displace native plant communities.

Management Plan


Management Options

Once established, West Indian marsh grass is extremely difficult to control. 

Cultural/Physical

 Scattered plants may be removed manually, however all stolons and roots must be removed to prevent regrowth. 

MechanicalBiological

There are no known biological control agents for West Indian marsh grass.

Chemical

Additional Resources