An Illustrated Guide to ARIZONA WEEDS
The University of Arizona Press
LARGE CRABGRASS, hairy crabgrass
LARGE CRABGRASS-Digitaria sanguinalis (L.) Scop.
DESCRIPTION-A weak branched summer annual which reproduces by seeds, and by stems spreading at the base and rooting at the lower joints. The flat leaf blades, 1/4 to 1/3 inch broad, and the sheaths have long stiff hairs. The flowering part is made up of 3 to 11 slender, fingerlike branches, 2 to 6 inches long, which may all arise from the same point at the stem tip (as in Bermudagrass), but usually several branches in addition arise a short distance below the tip. The small spikelets, 1/8 to 3/16 inch long, lie very close to the branch stems and come from only one side of the axis. The light yellow oval grain is about 1/12 inch long.
DISTRIBUTION-Large crabgrass, introduced from Europe, is a weed of moist soil. It is particularly obnoxious in lawns, where it forms coarse basal rosettes of leaves, but also is very common in cultivated fields, along streams, ditch banks, roadsides, and washes in southern and central Arizona, uncommon northward except in certain local areas; 100 to 6,000 feet elevation; flowering June to October.
SMOOTH CRABGRASS,small crabgrass-Digitaria ischaemum(Schreb.) Muhl.
DESCRIPTION-Similar to crabgrass, but smaller and not hairy. The bract enclosing the grain is blackish brown rather than pale yellow. A "recent" arrival in the Bermuda lawns of southern Arizona, and spreading rapidly. On the University of Arizona campus, smooth crabgrass was found in nearly pure stands occupying areas up to 30 feet or more in diameter.
Copyright (c) 1972 The Arizona Board of Regents