An Illustrated Guide to ARIZONA WEEDS
The University of Arizona Press
FIELD SANDBUR-Cenchrus pauciflorus Benth.
DESCRIPTION-Field sandbur is a restricted noxious-weed in Arizona. It is an erect or spreading annual, or sometimes a short-lived perennial, which reproduces by seeds, and by prostrate stems rooting at the lower nodes. It sometimes forms mats, then ascends, 4 inches to 3 feet long, with a shallow root system. The leaf blades are usually flat, twisted or folded, and 2 to 5 inches long. The flowering spikes are 1 1/2 to 4 inches long, often partially enclosed by the upper leaf sheath, and are composed mostly of 3 to 15 burs, loosely arranged, but may have 20 to 30 burs, and be very tightly congested.
The spiny, hairy yellowish burs are about 1/2 inch long, and mostly longer than broad. The numerous flattened spreading rigid spines, 1/8 to 1/4 inch long, often have a few curved bristles at the base. Each bur usually contains 2 seeds. There may be as many as 1,000 seeds produced by a single plant.
DISTRIBUTION-Field sandbur is a native American weed, and is very trouble- some when the burs mature. These injure clothing as well as skin. This weed is found mostly in dry sandy soil in cultivated fields, roadsides, lawns, washes, and waste places throughout the state, 100 to 6,000 feet elevation; flowering May to October, or until fall frosts.
SOUTHERN SANDBUR-Cenchrus echinatus L.
DESCRIPTION-Southern sandbur closely resembles field sandbur, but the burs are reddish, mostly broader than long, and are broadest at the base. (Those of field sandbur are broadest near the center.) These have a definite ring of many short, straight bristles at the base. Each bur usually contains 4 seeds.
DISTRIBUTION-Southern sandbur is an introduction from tropical America. It is not as widespread throughout the state as field sandbur, but it is a very trouble-some weed in the late summer crops, orchards, and alfalfa fields in the Yuma, Salt River, and Santa Cruz valleys, 100 to 4,000 feet elevation; flowering May to October, or until fall frosts.
Copyright (c) 1972 The Arizona Board of Regents