The World Flora Online

Open and often disturbed sites, versatile in soil tolerance, a noxious weed of roadsides and overgrazed pasturelands. The native range probably extends from Mexico City N across Mexico and the Great Plains of the United States. Outside this area , Solanum rostratum is a widely introduces weed in disturbed habittats (e.g. Russia and Australia).

Spreadingly branched, prickly, taprooted, annual herbs, stellate-pubescent throughout; stems to 1 cm in dam., armed with subulate or somewhat broad-based, yellow prickles 38 mm long; cauline stellae partly long-stalked, to 1 mm long, or all essentially sessile.
Sympodial units difoliate, usually almost geminate.
Leaves ovate to broadly ovate, once to twice pinnatifid, often pinnatisect near the base, with rounded or obtuse ultimate lobes; blades 7-16 cm long, prickly along the main veins, stellate-pubescent on both surfaces; petioles armed, 1/3-2/3 as long as the blades.
Inflorescences internodal, 4-11 cm long; 7-12-flowered.
Calyx at anthesis divided nearly to the base into linear lobes 6-10 mm long, tube campanulate, 1.5-2.5 mm long, densely stellate-pubescent or bristly, sometimes prickly. Corolla pentagonal, with ample, plicate, interpetalar tissue, 2.3-3.5 cm across, yellow, stellate-tomentose externally. Stamens with the long anther 1.0-1.4 cm long, arcuate, often suffused with red or purple, short anthers 6-8 mm long, yellow. Ovary glabrous, tightly invested in the developing calyx tube. Style 1-1.4 cm, slender, often purplish. Stigma unexpanded.
Fruit a spherical berry, 9-12 mm in diam. on slightly ascending pedicels 8-13 mm long, dry and splitting at maturity, accrescent calyx tube bearing numerous strait, yellow prickles often exceeding those of the stem in length;
Seeds 40-80 per berry, flattened-ovoid, 2.0-2.6 mm long, minutely foveolate, the lateral faces flat or undulate.

Coarse branching annual 3–10 dm, stellate-hairy throughout, the stems, cals, and to a lesser extent the lvs also beset with yellow spines 3–12 mm; lvs ovate or oblong in outline, deeply pinnately lobed, or the segments again lobed in larger lvs; racemes short-pedunculate, 3–15- fld, condensed at first, elongating to as much as 15 cm; fls light yellow, 2–3 cm wide; 4 anthers alike, yellow, the fifth much longer, curved, often purplish; cal accrescent and enclosing the berry; 2n=24. Dry prairies and plains; native to the Great Plains, now occasionally intr. throughout much of our range, especially westward.

Much-branched, stout, very prickly annuals up to 60 cm high with woody tap roots. Stems greenish; shortly stellate pubescent, densely armed with patent glabrous, yellow prickles up to 1 cm long. Leaves alternate, deeply lobed or pinnate, up to 10 cm long, 7 cm broad, on prickly petioles up to 5 cm long, lobes obtuse with broad sinuses, both surfaces yellowish green, sparsely to densely stellate pubescent, beset with yellow prickles especially on mid-rib and veins. Flowers in lateral racemes about 10 cm long, with prickly peduncles and pedicels, young calyx densely stellate pubescent, with small yellow prickles, corolla densely stellate pubescent outside, glabrous within, spreading to 1 cm in diameter, yellow. Fruits enclosed in enlarged, very prickly calyces, prickles yellow, up to 1-5 cm long, berries about 1 cm diameter, black, many-seeded. Seeds greyish-brown, compressed, 3 mm long, testas rugose and finely pitted. Annual herb, up to 1.5 m high; densely spiny. Spines curved. Leaves with blade pinnatifid. Flowers: inflorescence lateral; calyx spiny, accrescent, enclosing berry; corolla 20-35 mm in diameter, yellow; Dec.-Mar. Fruit a black berry, 10-15 mm in diameter, densely spinescent. Annual herb, up to 1.5 m high; densely spiny. Spines curved. Leaves with blade pinnatifid. Flowers: inflorescence lateral; calyx spiny, accrescent, enclosing berry; corolla 20-35 mm in diameter, yellow; Dec.-Mar. Fruit a black berry, 10-15 mm in diameter, densely spinescent.

Inflorescences to 10 cm long, many-flowered. Corolla yellow. Calyx enlarged in fruit, with dense, sharp, long, yellow prickles. Berries black.

Dry Grassland. Grassland, disturbed places; a tumble weed. Uncommon weed in disturbed areas. Uncommon weed in disturbed areas.

Native to the United States, northern and central Mexico. Originally from Mexico and the southern USA, but now a semi-cosmopolitan weed. In South Africa in Gauteng, Free State and Eastern Cape. Originally from Mexico and the southern USA, but now a semi-cosmopolitan weed. In South Africa in Gauteng, Free State and Eastern Cape.