Solanum americanum
Solanum emulans
American black nightshade, American black or common or West Indian nightshade, glossy nightshade, little white nightshade, small-flower nightshade, white nightshade
eastern black nightshade, eastern 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 1–5 cm;
blade simple, ovate to elliptic, 4.5–10.5 × 2–6 cm, margins entire to sinuate-dentate, base attenuate to rounded.
extra-axillary or leaf-opposed, unbranched, usually umbel-like, 3–10-flowered, 0.5–3 cm.
extra-axillary, unbranched, umbel-like, (2–)3–6-flowered, 1–2.5 cm.
erect or spreading, 0.3–1 cm in flower, to 1.5 cm in fruit.
straight and spreading in flower and recurved to reflexed in fruit, 0.5–1 cm.
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, 2–3 mm, glabrous to sparsely pubescent, lobes appressed in fruit, deltate;
corolla white, sometimes with yellow central star, rarely purplish, stellate, 0.5–1 cm diam., without interpetalar tissue;
stamens equal;
anthers ellipsoidal, 1–1.5 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.
dull or slightly shiny purplish black, globose, 0.5–1 cm diam., glabrous, with 6–9 sclerotic granules per fruit.
pale yellow to brown, 1–1.5 × 0.5–1.5 mm, minutely pitted.
yellowish, flattened, 1.5–2 × 1–1.5 mm, finely reticulate.
= 24.
= 24.
Solanum americanum
Solanum emulans
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 emulans has often been called S. ptychanthum Dunal (with the variant spelling ptycanthum), but that name is a synonym of S. americanum.
Solanum emulans is the most common species in the black nightshade group in northeastern North America. It can be distinguished from other North American species in the black nightshade group by its unbranched inflorescences, short anthers, appressed fruiting calyx lobes, and numerous sclerotic granules in the fruits.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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