NPSpecies

Data Source: White and Pyne 2003

Native Range: This species is cosmopolitan and believed to be native to the Mediterranean region (Agricultural Research Service USDA, 1971; Newman, 1993; Howard, 2004).; Data Source: http://plants.usda.gov, 10 August 2007 Legacy NPSpecies information may no longer be applicable, please remove if it is not applicable. In legacy NPSpecies Weedy value was Yes with comment: Roadsides, fields, waste places;common. A serious weed, difficult to eradicate. (Weakley 2007) In legacy NPSpecies Pest value was Yes with comment: Natureserve I-Rank: High/Medium. I-Rank Reasons Summary: Johnson grass has been shown to severely inhibit pioneer grass species which normally appear in abandoned fields and can persist in almost pure stands for many years. The massive size (up to 3 m tall) of this plant creates difficulties for the establishment of other plants and rapid growth of rhizomes also provides the plant with a competitive edge over other species. It is one of the most frequently listed noxious weeds in the U.S. and occurs throughout the entire southern half of the country. The plant is self-pollinated, aggressive, and wind dispersed though humans often disperse it during field cultivation. Although it can colonize undisturbed sites as a pioneer species, it is often found in old fields or previously cultivated areas. Control is difficult and costly and, although some selective herbicides have been developed, such treatment usually impacts natives.

Park Species Data Source: White and Pyne 2003