Hymenachne amplexicaulis

Common Name(s): West Indian marsh grass

Non-Native to Florida

Origin: West Indies, tropical Central and South America 1

This species appears on the following legally prohibited plant lists

Federal Noxious Weed List Florida Noxious Weed List Florida Prohibited Aquatic Plants List
No No No

Cypress Lake Study Information

UF-IFAS Assessment of Non-Native Plants in Florida’s Natural Areas

CATEGORY I on the Florida Exotic Pest Plant Council’s (FLEPPC) 2017 List of Invasive Plant Species

More Info: Plant Management in Florida Waters

Download a page (PDF) from Identification and Biology of Nonnative Plants in Florida’s Natural Areas – Second Edition1

Download a recognition card (PDF) from Invasive and Non-native Plants You Should Know2

For general information about West Indian marsh grass, download this UF/IFAS-EDIS publication, Exotics in the Wetlands: West Indian marsh grass, by R. Diaz, W.A. Overholt and J.P. Cuda.

For brief control information, see Efficacy of Herbicide Active Ingredients Against Aquatic Weeds (EDIS Pub #SS-AGR-44)

Hymenachne amplexicaulis 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).

Appearance

Robust perennial grass from stolons. Stems floating, creeping, or ascending to 1m (3 ft) or more in height; sparingly branched, rooting at the lower nodes; stems pithy, not hollow.

Leaves

Sheaths glabrous but with hairs on upper margins; ligule a membrane. Leaf blades flat, to 35 cm (14 in) long and to 4 cm (1.6 in) wide; cordate at the base and clasping the stem (amplexicaul); glabrous but with long hairs on lower margins.

Flowers

In a spike-like, densely flowered panicle, to 26 cm (10 in) long and ~1 cm (0.4 in) wide; spikelets short-stalked.

Fruit

3–4 mm (0.12 – 0.16 in) long.

Ecological threat

Displacing native maidencane communities; colonizing, and becoming difficult to control along drainage canals of south central Florida. FLEPPC Category I

Distribution:

C, SW, SE

Text from Invasive and Non-native Plants You Should Know – Recognition Cards 1

 

View the herbarium specimen image from the University of Florida Herbarium Digital Imaging Projects.

 

Citations

1. Identification and Biology of Nonnative Plants in Florida’s Natural Areas – Second Edition,
by K.A. Langeland, H.M. Cherry, et al. University of Florida-IFAS Publication # SP 257. 2008.

2. Invasive and Non-native Plants You Should Know – Recognition Cards,
by A. Richard and V. Ramey. University of Florida-IFAS Publication # SP 431. 2007.

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