Solanum americanum
Solanum chenopodioides
American black nightshade, American black or common or West Indian nightshade, glossy nightshade, little white nightshade, small-flower nightshade, white nightshade
velvety nightshade, whitetip 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 1–3 cm;
blade simple, narrowly ovate to elliptic, 1.5–5(–7) × 0.5–3.5 cm, margins entire or sinuate, base cuneate to decurrent.
extra-axillary or leaf-opposed, unbranched, usually umbel-like, 3–10-flowered, 0.5–3 cm.
extra-axillary or leaf-opposed, unbranched or rarely forked, umbel-like, 3–7(–10)-flowered, 1–3(–4) cm, fruiting peduncles sharply reflexed from base.
erect or spreading, 0.3–1 cm in flower, to 1.5 cm in fruit.
0.5–1 cm in flower and fruit, reflexed downward in 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, 2–3.5 mm, sparsely pubescent, lobes deltate, appressed in fruit;
corolla white or purplish, with greenish, yellowish, or brown central star, stellate, 0.8–1.5 cm diam., with sparse interpetalar tissue;
stamens equal;
anthers ellipsoidal, 2–3 mm, dehiscent by terminal pores that open into longitudinal slits;
ovary glabrous.
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 purplish black, globose, 0.5–1 cm diam., glabrous, without sclerotic granules.
pale yellow to brown, 1–1.5 × 0.5–1.5 mm, minutely pitted.
pale yellow, flattened, 1–1.5 × 1–1.5 mm, minutely pitted.
= 24.
= 24.
Solanum americanum
Solanum chenopodioides
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 chenopodioides has been introduced sporadically and is occasionally adventive in North America. It is distinctive in having the fruiting peduncles strongly reflexed downward, but is otherwise difficult to distinguish from S. pseudogracile, with which it may be conspecific.
The illegitimate superfluous name Solanum gracile Dunal has often been used for S. chenopodioides (for example, J. K. Small 1913; A. E. Radford et al. 1968). W. G. D’Arcy (1974) included S. gracile (and its replacement name S. ottonis) in the synonymy of S. nigrescens but the taxa are distinct.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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