Solanum nigrescens
Solanum citrullifolium
divine nightshade
melon-leaf nightshade, watermelon 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 2–7 cm;
blade simple to compound, broadly ovate, 4–10(–15) × 3–8 cm, margins bipinnately lobed or divided with 3–4 main leaflets per side, these with obtuse or rounded lobes, base truncate.
extra-axillary or leaf-opposed, unbranched, umbel-like to racemelike, (2–)5–10-flowered, 1–3.5 cm.
extra-axillary, unbranched, 4–10-flowered, 3–11 cm.
spreading and 0.5–1 cm in flower, spreading and 1–1.5 cm in fruit.
1–2 cm in flower, 1–2 cm and erect 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, 2.5–3.8 mm, densely glandular-pubescent, lobes linear-lanceolate;
corolla violet or blue, pentagonal-stellate, 2.5–3.5 cm diam., with interpetalar tissue at margins and bases of lobes;
stamens unequal, lowermost much longer and curved;
anthers narrow and tapered, dehiscent by terminal pores, short anthers yellow, 6–10 mm, longer anther purplish, 11–16 mm;
ovary glabrous.
dull green or purplish, globose, 0.5–0.8 cm diam., glabrous, with (4–)5–6(–13) sclerotic granules.
brown, globose, 0.8–1.2 cm diam., glabrous, dry, without sclerotic granules.
tan, flattened, 1.2–1.5 × 1–1.1 mm, finely pitted.
dark brown, flattened, 2.3–3 × 2–2.5 mm, reticulately wrinkled, ridged, or undulate.
= 24.
= 24.
Solanum nigrescens
Solanum citrullifolium
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.)
North American plants identified as Solanum heterodoxum Dunal are largely misidentifications of S. citrullifolium. Solanum heterodoxum in the current sense is now restricted to Mexico.
Varieties 2 (2 in the flora).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Stems scattered-prickly with fewer than 20 prickles per cm of stem; prickles often to 1 mm diam. at base; stems densely glandular-pubescent. | var. citrullifolium |
1. Stems densely bristly with 25+ bristles per cm of stem; bristles mostly less than 0.5 mm diam. at base; stems sparsely glandular-pubescent. | var. setigerum |
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