Solanum nigrescens
Solanum rostratum
divine nightshade
buffalo berry, buffalo-bur, buffalobur nightshade, horned nightshade, spiny nightshade
petiolate;
petiole 0.5–2 cm;
blade simple, ovate to ovate-elliptic, 4–10.5 × 2–5 cm, margins entire or shallowly sinuate-dentate, base decurrent.
petiolate;
petiole 2–10 cm;
blade simple to twice-compound, ovate to elliptic, (2–)4–16 × 3–12 cm, margins lobed to 1–2 times divided with 2–4 main leaflets per side, leaflets with deep, rounded lobes, base truncate to subcordate.
extra-axillary or leaf-opposed, unbranched, umbel-like to racemelike, (2–)5–10-flowered, 1–3.5 cm.
extra-axillary, unbranched, 5–12-flowered, 4–11 cm.
spreading and 0.5–1 cm in flower, spreading and 1–1.5 cm in fruit.
0.5–1.5 cm in flower, erect and 0.5–1.5 cm in fruit.
radially symmetric;
calyx not accrescent, unarmed, 1–2 mm, sparsely pubescent, lobes deltate;
corolla white, rarely purplish, often with green or purplish central star, stellate, 1–1.5 cm diam., with sparse interpetalar tissue;
stamens equal;
anthers ellipsoidal, 2–3 mm, dehiscent by terminal pores that open into longitudinal slits;
ovary glabrous.
bilaterally symmetric;
calyx accrescent and tightly covering fruit, densely prickly or bristly, 7.5–12.5 mm, densely stellate-pubescent, lobes linear to lanceolate;
corolla yellow, rotate-pentagonal, 1.5–3.5 cm diam., with abundant interpetalar tissue;
stamens unequal, lowermost much longer and curved;
anthers narrow and tapered, dehiscent by terminal pores, short anthers 4, yellow, 6–8 mm, longer anther reddish or purplish, 10–14 mm;
ovary glabrous.
dull green or purplish, globose, 0.5–0.8 cm diam., glabrous, with (4–)5–6(–13) sclerotic granules.
brown, globose, 1–1.2 cm diam., glabrous, dry, without sclerotic granules.
tan, flattened, 1.2–1.5 × 1–1.1 mm, finely pitted.
dark brown, flattened, 2–3 × 1.8–2 mm, minutely pitted and irregularly ridged.
= 24.
= 24.
Solanum nigrescens
Solanum rostratum
Solanum nigrescens is widespread in Central and northern South America and the Caribbean and extends northward into the southeastern United States along the Gulf Coast and slightly inland. Where sympatric with S. americanum, it can be distinguished by its longer anthers and dull green or purplish berries with appressed to spreading calyx lobes. Plants collected as weeds in rice and sugarcane fields of Louisiana and provisionally identified as the Chinese species S. merrillianum T. N. Liou are somewhat intermediate between S. americanum and S. nigrescens and could represent recent hybrid populations (S. Knapp et al. 2019). Solanum nigrescens differs from S. douglasii in its shorter anthers and longer filaments relative to anther length; moreover, S. douglasii is usually found west of the Rocky Mountains, whereas S. nigrescens occurs in the southeastern United States. The ranges of S. nigrescens and S. interius overlap (for example, in Texas). Solanum nigrescens may be distinguished from S. interius by its usually acute calyx lobes, smaller seeds, and more numerous sclerotic granules in the fruits. Solanum nigrescens differs from S. nigrum in its more slender peduncles and pedicels, smaller seeds, and fruits with sclerotic granules.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Solanum rostratum is widespread in the central Mexican highlands from Chihuahua and Coahuila to Puebla and Oaxaca, and its native range likely extends from Mexico City north to the United States Great Plains. It is widely introduced outside this presumed area of origin.
Solanum rostratum is considered a noxious weed in several states. It is often invasive in gardens, pastures, and disturbed areas. The plants are extremely spiny, and there are reports of pigs being poisoned by eating the berries and roots. This species is thought to be the original host of the Colorado potato beetle (Leptinotarsa decemlineata) before potatoes were widely cultivated in the western and central United States. The beetle then adopted potatoes as its primary host and rapidly spread eastward.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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