Solanum douglasii
Solanum rostratum
Douglas' nightshade, greenspot nightshade
buffalo berry, buffalo-bur, buffalobur nightshade, horned nightshade, spiny nightshade
petiolate;
petiole 0.5–3(–7) cm;
blade simple, ovate, 1–5(–9) × 0.5–3(–6) cm, margins entire to coarsely and irregularly toothed, base truncate to acute and 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, racemelike, 2–7(–14)-flowered, 2–4 cm.
extra-axillary, unbranched, 5–12-flowered, 4–11 cm.
0.5–1 cm in flower and fruit, nodding or deflexed downward in fruit.
0.5–1.5 cm in flower, erect and 0.5–1.5 cm in fruit.
radially symmetric;
calyx not accrescent, unarmed, 2–3 mm, sparsely pubescent, lobes deltate;
corolla white with yellow-green to brownish central star, stellate, 1–2 cm diam., without interpetalar tissue;
stamens equal;
anthers ellipsoidal and slightly tapered towards the tips, (2.5–)3–4.5 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 purplish black, globose, 0.5–1 cm diam., glabrous, with (2–)6–8 sclerotic granules per fruit.
brown, globose, 1–1.2 cm diam., glabrous, dry, without sclerotic granules.
pale yellow to tan, flattened, 1.5–2 × 1–1.5 mm, finely reticulate.
dark brown, flattened, 2–3 × 1.8–2 mm, minutely pitted and irregularly ridged.
= 24.
= 24.
Solanum douglasii
Solanum rostratum
Solanum douglasii is most commonly found west of the Rocky Mountains. It can be difficult to distinguish from S. nigrescens, but its longer, slightly tapered anthers on very short (relative to anther length) filaments is a good distinguishing character for plants in flower. The buds of S. douglasii are more pointed than those of S. nigrescens.
(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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