Dallisgrass (Paspalum dilatatum)
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Dallisgrass is a perennial grass that is cultivated for pasture in many places. However, it is less commonly used for forage in California because of its weedy character. In addition, its seed heads are susceptible to an ergot fungus, Calviceps paspali, that is toxic to livestock when ingested. Its rapid growth and profuse seed production enable it to quickly invade agricultural land, especially rice, waterway margins, and managed urban sites. Except for the Great Basin and Sonoran Desert, dallisgrass is found throughout California to an elevation of 1300 feet (about 400 m).
Gardens, turf, vineyards, orchards, irrigation and drainage ditches, canals, pond and reservoir margins, rice fields, and stream banks.
Dallisgrass plants form loose bunches that grow from 1 to 5 feet (about 1.5 m) tall. Plants grow from prostrate with erect tips to totally erect. The leaf sheath is somewhat flattened and its base is hairy, often tinged red, and usually inflated. The underground stems are fairly short and have areas that appear as concentric rings. Dallisgrass can be distinguished from tall fescue, Festuca arundinacea, which forms clumps rather than loose bunches. Also similar in appearance is knotgrass, Paspalum distichum, which does not have the flattened stems and hairless stem joints (nodes) of dallisgrass; rather, it has rounded stems and hairy nodes. In mowed sites, such as lawns and recreational fields, if may be confused with crabgrass but crabgrass leaves are soft whereas dallisgrass leaves are stiffer.
The ligule is firm and membranous. The collar margin usually has a few spreading hairs at the edges. There are no auricles.
Dallisgrass blooms from May through November. The flower head has three to six spikes that arise from different points along the stem and often droop. Although similar to the flower head of goosegrass, Eleusine indica, dallisgrass is distinguished by its longer and less stiff flower head.
Reproduces by seed.
Related or similar plants
- Crabgrass, Digitaria spp.
- Goosegrass, Eleusine indica
- Knotgrass, Paspalum distichum
- Tall fescue, Festuca arundinacea