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Megathyrsus maximus

Common Name: Guinea grass

Family: Poaceae

Common Synonyms: Panicum maximum, Urochloa maxima

USDA Hardiness Zone: 8a-11

Growth Habit: Herb

Origin: Africa

FISC Category: 2

FDACS Listed Noxious Weed: No

Introduction Date: Earliest Florida specimen available vouchered in 1933

IFAS Assessment:

  • North: CAUTION
  • Central: CAUTION
  • South: INVASIVE
Megathyrsus maximus
Pete Diamond
Megathyrsus maximus
Brenda Herring

Description

Robust, densely-tufted perennial grass to 3 m tall. Rhizome may bear hairy reduced-leaf remnants. Stem stout, erect, glabrous to hairy, nodes often densely hairy. Leaf sheath glabrous to stiff-hairy, often with dense patches of hair at junction with leaf blade. Ligule membranous, to 6 mm long. Leaf blade flat, linear, to 90 cm long and 3.5 cm wide, glabrous to softly or coarsely hairy on upper surface, margin may be rough to the touch. Inflorescence a many-branched, erect or slightly nodding panicle, to 60 cm tall and 20 cm wide, with 3-7 whorled lower branchlets. Spikelets clustered on branchlets, short stalked, to 4 mm long, green to purplish, oblong, blunt-tipped or slightly pointed, glabrous or slightly hairy, first glume 1/3 length of spikelet, second glume equal length to spikelet, upper floret fertile, developing a dull, white seed.

Habitat

Mesic flatwoods, coastal strand, maritime hammock, xeric hammock, sandhill, scrub, pine rockland.

Comments

Fast growing. Widely established except in the panhandle.

Map of species distribution

Control Methods

  • Manual: NA
  • Chemical: 3-5% Glyphosate foliar, Glyphosate 2% plus Imazapyr 0.5%, or Imazapyr 1-2% yield similar results, retreat at 2-4, 3-5, 4-6 months respectively (IFAS).
  • Biological: NA

Control Notes

NA

References

Langeland, K.A., H.M. Cherry, C.M. McCormick, K.C. Burks. 2008. Identification and Biology of Non-Native Plants in Florida's Natural Areas-Second Edition. IFAS Publication SP 257. University of Florida, Gainesville, Florida.

Tropical Forages Fact Sheet. http:/www.tropicalforages.info/key/forages/media/Htmi/Panicum_maximum.htm. Accessed on December 10, 2013.

Dave's Garden. 2013. PlantFiles: Guinea grass, Panicum maximum. http://davesgarden.com/guides/pf/go/59767/. Accessed on December 10, 2013.

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