An Illustrated Guide to ARIZONA WEEDS

The University of Arizona Press



PEA FAMILY-Leguminosae

SILKY SOPHORA-Sophora nuttalliana B. L. Turner (S. sericea Nutt.)

DESCRIPTION-A low, silky hairy, silver perennial which reproduces by seeds and deep horizontal roots and rhizomes. The weak stems are often woody, and branch at the base with some spreading and others erect, 2 to 12 inches long. The alternate leaves are 1 to 2 inches long, and divided once into 4 to 12 pairs of small leaflets, 1/4 to nearly 1/2 inch long, with fine silky hairs pressed close to the surface.

The white or yellowish flowers are pealike, 1/2 to 3/4 inch long, and occur on short flower branches 2 to 5 inches long at the end of the stems. The pods are somewhat woody, 1/2 to 1 1/2 inches long, contain 1 to 4 seeds, and are tipped by a sharp pointed beak. The pods are constricted between the seeds, so each seed is clearly outlined. The seeds are kidneyshaped, tan colored with the surface smooth, and 1/8 to 1/4 inch long.

DISTRIBUTION-Silky sophora is a native plant, growing in colonies in sandy or heavy disturbed soil, as where floodwaters collect. It is abundant locally, often covering extensive areas, and becoming a weed in cultivated fields, roadsides, and on the open ranges on sandy creek bands, in swales, and bottomlands. Found in northern Arizona from Apache to Mohave and Yavapai counties, also in Cochise and Pima counties; 3,500 to 7,000 feet elevation; flowering April to June. Silky sophora is hard to eradicate because of its underground stems, and should not be allowed to become established.

POISONOUS PROPERTIES-Silky sophora is reported to cause livestock poisoning if eaten in large amounts, and the seeds are known to contain a poisonous alkaloid. Animals seldom eat this plant, and no livestock poisoning due to silky sophora in Arizona is known definitely.

Copyright (c) 1972 The Arizona Board of Regents

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