Silverleaf nightshade, white horsenettle, trompillo

Herbs or shrubs, perennial, erect, rhizomatous, sparsely to densely armed, to 1 m, prickles orange to brown, straight, to 5 mm, densely silvery-pubescent, hairs sessile or subsessile, stellate, scalelike, 10–15-rayed, central ray shorter than lateral rays, lateral rays fused at center. Leaves petiolate; petiole 1–5 cm; blade simple, lanceolate to oblong, 5–15 × 0.5–3 cm, margins undulate, subentire to sinuate or shallowly lobed, lobe margins entire, base truncate to cuneate. Inflorescences extra-axillary, unbranched, 3–5(–7)-flowered, 3–5 cm. Pedicels 1–3 cm in flower, reflexed and 1–3 cm in fruit. Flowers radi­ally symmetric; calyx not accrescent, unarmed or with sparse prickles, 5–10 mm, densely silvery-stellate-pubescent, lobes linear-lanceolate; corolla pale to deep blue or violet, rarely white, pentagonal-stellate, 2–3(–3.5) cm diam., with abundant interpetalar tissue; stamens equal; anthers narrow and tapered, 6–9 mm, dehiscent by terminal pores; ovary glabrous to densely stellate-pubescent. Berries yellow to orange, drying brown or black, globose, 0.5–1.5 cm diam., glabrous, without sclerotic granules. Seeds yellowish, flattened, 3–5 × 2–4 mm, minutely pitted. 2n = 24, 48, 72.

Flowering Mar–Nov. Dry sites, open woods, dis­turbed areas, roadsides, railroads, fields; 0–2100 m; Ala., Ariz., Ark., Calif., Colo., Fla., Ga., Idaho, Ill., Ind., Kans., Ky., La., Md., Miss., Mo., Nebr., Nev., N.Mex., N.C., Okla., Oreg., S.C., Tenn., Tex., Utah, Wash.; Mexico; West Indies; South America (Argentina, Chile, Paraguay, Uruguay); introduced elsewhere in South America (Colombia, Peru), Eurasia (Mediterranean, Middle East, India, Pakistan), Africa, Australia.

Solanum elaeagnifolium has a disjunct native dis­tribution. It occurs in arid regions of the southwestern United States and Mexico and also in Argentina, Chile, Paraguay, and Uruguay. North American plants are diploid, whereas those in Argentina are diploid, tetra­ploid, or hexaploid. It is invasive and considered a nox­ious weed in 21 states in the flora area as well as in many tropical and subtropical regions worldwide. It is toxic to livestock and can form large, rhizomatous patches that are difficult to eradicate.

A white-flowered form has been recognized as Solanum elaeagnifolium forma albiflorum Cockerell.