An Illustrated Guide to ARIZONA WEEDS

The University of Arizona Press



PIGWEED FAMILY-Amaranthaceae

WOOLLY TIDESTROMIA-Tidestromia lanuginosa (Nutt.) Standl.

DESCRIPTION-A brittle stemmed summer annual, reproducing by seeds. The whitish stems often are bright scarlet in the fall. They are erect, prostrate, or drooping on the ground, and many-branched. Usually radiating from the root, they are 3 inches to 1 1/2 feet high or long, and may spread to 5 feet in diameter either on the ground or above. The densely hairy leaves are opposite, football or oval shaped, 1/3 to 2 inches long, and 1/4 to 1 inch broad. The 2 opposite leaves are usually of different sizes.

The small yellowish flowers, about 1/8 inch long, are borne in a few flowered clusters on the leaf axils. They have 5 stiff papery flower parts and 5 stamens. The small seeds (fruits) are almost globeshaped.

DISTRIBUTION-Woolly tidestromia grows on rocky or sandy soil. It is widespread in Arizona, and is conspicuous after the start of the summer rains, forming whitish mats on mesas, sandy plains, desert slopes, and juniper flats. In southern Arizona, this native plant has invaded the newly irrigated lands, and has become a pest in cotton fields, as in Avra Valley and Pima County, and in other cultivated crops and irrigation ditches; 100 to 6,000 (mostly lower) feet elevation; flowering July to October. It is also one of the hosts of the beet leafhopper.

Copyright (c) 1972 The Arizona Board of Regents

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