Solanum americanum
Solanum interius
American black nightshade, American black or common or West Indian nightshade, glossy nightshade, little white nightshade, small-flower nightshade, white nightshade
deadly nightshade, plains black nightshade, plains black or deadly nightshade
petiolate;
petiole 1–4 cm;
blade simple, ovate to ovate-elliptic, 2–10.5 × 1–4.5 cm, margins entire or shallowly sinuate-dentate, base decurrent.
petiolate;
petiole 0.5–3.5 cm;
blade simple, ovate to ovate-lanceolate, 4.5–11 × 2.5–7 cm, margins entire to sinuate-dentate, base cuneate to rounded or slightly decurrent.
extra-axillary or leaf-opposed, unbranched, usually umbel-like, 3–10-flowered, 0.5–3 cm.
extra-axillary, unbranched, (2–)3–8-flowered, 2.5–3.5 cm.
erect or spreading, 0.3–1 cm in flower, to 1.5 cm in fruit.
spreading in flower, recurved to reflexed in fruit, 0.5–1 cm in flower and fruit.
radially symmetric;
calyx somewhat accrescent, unarmed, 1–3 mm, lobes deltate, strongly reflexed in fruit;
corolla white, sometimes with yellowish central star, stellate, 0.4–0.8 cm diam., without interpetalar tissue;
stamens equal;
anthers ellipsoidal, 0.7–1.5 mm, dehiscent by terminal pores that open into longitudinal slits;
ovary glabrous.
radially symmetric;
calyx not accrescent, unarmed, 2–5 mm, sparsely pubescent, lobes lanceolate, sometimes reflexed in fruit;
corolla white, sometimes tinged with purple, with yellowish central star, stellate, 0.5–1 cm diam., without interpetalar tissue;
stamens equal;
anthers ellipsoidal, 1.8–2.5 mm, dehiscent by terminal pores that open into longitudinal slits;
ovary glabrous.
shiny purplish black, globose, 0.5–1 cm diam., glabrous, with (0–)2–4(–6) sclerotic granules, usually 2–4 larger and 2 smaller.
shiny purplish black, globose, 1–1.5 cm diam., glabrous, with 2–4 sclerotic granules.
pale yellow to brown, 1–1.5 × 0.5–1.5 mm, minutely pitted.
yellowish to brown, flattened, 1.8–2 × 1.5–1.6 mm, finely reticulate.
= 24.
= 24.
Solanum americanum
Solanum interius
Solanum americanum is a morphologically variable and globally distributed weedy species. It has often been confused with other species in the black nightshade group such as S. emulans, S. nigrescens, S. nigrum, and S. pseudogracile and has often been referred to as S. nodiflorum in floristic treatments. It is distinguished by its very short anthers and shiny black mature fruits with strongly reflexed calyx lobes and usually two to four (rarely none or as many as six) sclerotic granules per fruit. Leaf shape and pubescence can vary considerably throughout its range, and there are some suspected cases of introgression with other species such as S. nigrescens or S. pseudogracile. The name S. nigrum has been misapplied to S. americanum (for example, A. E. Radford et al. 1968).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Solanum interius is endemic to North America and is most common in the Great Plains and eastern Rocky Mountains. Distinctive characters are the basal flower with its pedicel articulated above the base and the very large seeds. In Texas, S. interius can be very difficult to distinguish from S. nigrescens, but S. interius usually has longer calyx lobes. Records of S. interius from Saskatchewan are actually S. emulans.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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