An Illustrated Guide to ARIZONA WEEDS

The University of Arizona Press




BROWNTOP PANICUM-Panicum fasciculatum Sw. var. reticulatum (Torr.) Beal

DESCRIPTION-A tall annual, erect or spreading, and branching from the lower stem joints, 1 to nearly 4 feet high, reproducing by seeds. The leaves are thinly hairy or hairless, and 1/4 to 1/2 inch broad. The flowering part is short, mostly 2 to 6 inches long, with erect to slightly spreading spinelike branches, 2 to 4 inches long.

The spikelets are green when young, and yellow or bronze when ripe. They are hairless, less than 1/8 inch long, and minutely cross ridged. The grain is dull, also minutely cross ridged and 1/8 inch or less long, with a blunt tip.

DISTRIBUTION-Browntop panicum is a native weed, infrequent in Arizona in sandy washes, river bottoms, and waste places until a few years ago. It has now become common, and is often a nuisance in cultivated crops in the irrigated areas of southern Arizona, such as the Salt and Gila rivers, Santa Cruz, Avra, and Yuma valleys; 100 to 3,500 feet elevation; flowering June to October.

ARIZONA PANICUM-Panicum arizonicum Scribn. & Merr.

DESCRIPTION-Closely resembles browntop panicum, but is shorter, 1/2 to 2 feet high. The spikelets are about the same color, but are short hairy, slightly longer than 1/8 inch, and not minutely cross ridged. The grains are short pointed.

DISTRIBUTION-Arizona panicum is a native weed of mesas, sandy washes, rocky slopes, and canyons throughout southern Arizona; up to 5,000 feet. It also is a common farm weed found in the same general places, and flowering at the same time as browntop panicum.

Copyright (c) 1972 The Arizona Board of Regents

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