An Illustrated Guide to ARIZONA WEEDS

The University of Arizona Press

SILVERLEAF NIGHTSHADE, white horsenettle, trompillo



SILVERLEAF NIGHTSHADE-Solanum elaeagnifolium Cav.

DESCRIPTION-A prohibited noxious weed in Arizona, silverleaf nightshade is an upright silvery perennial, usually prickly, 1 to 3 feet high, which reproduces by seeds and by deeply penetrating or creeping rhizomes. The surface of the entire plant is covered by densely matted, tiny starlike hairs, which give its characteristic silvery color.

The stems, leaves, and flower stalks may all bear slender yellowish spines; these may be scarce or sometimes wholly lacking. The thick leaves are alternate, 1 to 4 inches long (including the stalks), 1/4 to 1 inch broad, and are darker above than underneath. They are lanceshaped to narrowly oblong, the margins smooth to deeply wavy.

The showy flowers arc deep violet or blue, 3/4 to 1 inch across, wheelshaped and 5-lobed. They are stalked, and in a few flowered clusters at the ends of the stems, or on short branches. The berrylike pods, 1/3 to 1/2 inch in diameter, are mottled green, dull yellow, or orange yellow when mature. They are hairless and smooth, pulpy, somewhat berrylike, and contain numerous seeds.

The nearly diskshaped seeds are about 1/8 inch long, yellowish brown, and the surface is shiny and finely granular.

DISTRIBUTION-Silverleaf nightshade is a native plant, growing preferably on moist sandy soil. It is an obnoxious weed throughout the state, but is especially troublesome in the irrigated valleys of southern Arizona, where it is a pest in all types of crops, especially cotton, sorghum, and alfalfa. Abundant on ditchbanks, row ends, along roadsides, waste places, sandy washes, and bottom lands; 100 to 5,500 elevation; flowering April to October. It is reported that the Pima Indians use the crushed berries in making cheese.

POISONOUS PROPERTIES-As little as 0.1% of the animal's weight of silverleaf nightshade has been found toxic to cattle. The ripe seedpods are slightly more toxic than the green ones, and the leaves were least poisonous. The leaves and seedpods of silverleaf nightshade contain the poisonous alkaloid solanine.

Copyright (c) 1972 The Arizona Board of Regents

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