An Illustrated Guide to ARIZONA WEEDS
The University of Arizona Press
GREEN FOXTAIL, green bristlegrass, bottlegrass
GREEN FOXTAIL-Setaria viridis (L.) Beauv.
DESCRIPTION-Weak annuals forming spreading clumps, ]/2 to 1 3/4 or 3 feet high, reproducing only by seeds. The flattened leaf blades are usually less than 6 inches long, and l/4 to 3/8 inch broad. The flowering part is a bristly cylindrical spike at the end of a stem 3/4 to 3 inches long. The spikelets, about 1/12 to 1/8 inch long, are densely crowded on the spike. At the base of each, there arises 1 to 3 (sometimes 4) tawny or purplish bristles, mostly 3 to 4 times longer than the spikelets. The nearly oval grains are about 1/16 inch long, greenish to dark brown and faintly wrinkled, flattened on one side and rounded on the other.
DISTRIBUTION-Green foxtail, native of Europe, is a common weed in moist soil throughout Arizona, and is a nuisance in cultivated fields in irrigated valleys. It is also found in lawns, ditches, along roadsides, streams, and in barren spots in pine forest openings; 100 to 8,200 feet elevation; flowering June to November.
YELLOW FOXTAIL, YELLOW BRISTLEGRASS-Setaria glauca (L.) Beauv. (S. lutescens [Weigel] Hubbard)
DESCRIPTION-An annual, closely resembling green foxtail. The leaves are longer, 4 to 12 inches long, and the flowering spikes may be 4 inches long. It differs principally in that there are at least 5, and usually more (5 to 20), bristles at the base of each spikelet. The grains are about 1/12 inch long, and thick pointed at the tip.
DISTRIBUTION-Yellow foxtail, also introduced from Europe, is found in the same type of places with the same general distribution as green bristlegrass, but is infrequent; 100 to 7,500 feet elevation; flowering July to October.
Copyright (c) 1972 The Arizona Board of Regents