Cogon-X

DESCRIPTION: Cogon grass is a perennial, rhizomatous grass that grows from 2 to over 4 feet in height. The leaves are about an inch wide, have a prominent white midrib, and end in a sharp point. Leaf margins are finely toothed and are embedded with silica crystals. The upper surface of the leaf blade is hairy near the base; the undersurface is usually hairless. The flowers are arranged in a silvery, cylindrical, branching structure, or panicle, about 3-11 inches long and 1½ inches wide.

BIOLOGY & SPREAD: Cogon grass reproduces both vegetatively and from seed.  A single plant can produce several thousand very small seeds that may be carried great distances by the wind. Vegetative spread of cogon grass is aided by its tough and massive rhizomes that may remain dormant for extended periods of time before sprouting.  Rhizomes of cogon grass may be transported to new sites in contaminated fill dirt or by equipment used in infested areas.

Geographical Distribution: Cogon grass has been reported as a weed in 73 countries and on all six continents. It is widely distributed in Africa, Australia, southern Asia, and the Pacific Islands, and less extensively distributed, or a less serious problem, in southern Europe, the Mediterranean, the Middle East, Argentina, Chile, Colombia, the Caribbean, and the southeastern United States (Fig. 3). It has been found at latitiudes from 45°N (Japan) to 45°S (New Zealand), and from sea level to over 2,000 m elevation (Holm et al., 1977). In the United States, cogon grass occurs in Florida, Georgia, Alabama, Mississippi, Louisiana, South Carolina, and Texas (Fig. 4). It is distributed throughout Florida (Langeland and Burks, 1998) and is widely distributed in Mississippi (Patterson and McWhorter, 1983; C. Bryson, pers. comm.), and southern Alabama (Dickens, 1974). It is established at some locations in Louisiana, South Carolina (Allen et al., 1991; Bryson and Carter, 1993), southern Georgia (Byrd and Bryson, 1999; Coile, pers. comm.), and in Tyler County, Texas (USGS, 1999).

A red-tipped ornamental cultivar, Imperata cylindrica 'Rubra,' is extensively promoted as Red Baron, or Japanese Blood Grass, in many other states (Hall, 1998; C. Bryson, pers. comm.). This red-colored ornamental cultivar can revert to the green form, which is the invasive variety (Greenlee, 1992; Dozier et al., 1998; Hall, 1998; C. Bryson, pers. comm.). Plants propagated by tissue culture, rather than division, seem particularly prone to revert to the aggressively spreading green form (Greenlee, 1992).

Imperata cylindrica 'Rubra' is very cold tolerant (Shilling et al., 1997), and has persisted in Michigan for several years in an ornamental garden (C. Bryson, pers. comm.). Should this cold-tolerant cultivar be introduced into the southeast and hybridize with I. cylindrica var. major, hybrids might exhibit both invasiveness and cold tolerance, allowing for significant range extension to the north and west (Shilling et al., 1997).