Solanum americanum
Solanum perplexum
American black nightshade, American black or common or West Indian nightshade, glossy nightshade, little white nightshade, small-flower nightshade, white 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 1–6 cm;
blade simple, broadly ovate, 7–22 × 8–18 cm, margins shallowly to deeply lobed with 2–5 lobes per side, lobe margins entire to coarsely lobed, base truncate to cuneate and often oblique.
extra-axillary or leaf-opposed, unbranched, usually umbel-like, 3–10-flowered, 0.5–3 cm.
extra-axillary, forked to several times branched, to 15-flowered, 7–15 cm.
erect or spreading, 0.3–1 cm in flower, to 1.5 cm in fruit.
1–2 cm in flower, curved downward and to ca. 2.4 cm 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 or sparsely prickled, 7–13 mm, densely stellate-pubescent, lobes ovate-lanceolate;
corolla lavender, stellate to stellate-pentagonal or rotate-stellate, 2–4.4 cm diam., with sparse to moderate interpetalar tissue at margins and base of lobes;
stamens equal;
anthers narrow and tapered, 4–10 mm, dehiscent by terminal pores;
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.
yellow, subglobose, 1.8–3.5 × 2–4 cm, glabrous, without sclerotic granules.
pale yellow to brown, 1–1.5 × 0.5–1.5 mm, minutely pitted.
yellow, flattened, ca. 2 × 2.5 mm, minutely pitted.
= 24.
= ca. 72.
Solanum americanum
Solanum perplexum
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 perplexum is similar to S. dimidiatum and was placed in synonymy with S. dimidiatum by W. G. D’Arcy (1974). The two species can be distinguished by their indumentum [golden stellate hairs with six to eight (rarely as few as four) lateral rays with the central ray one- or two-celled and longer than lateral rays in S. perplexum versus whitish stellate hairs with six to ten (rarely as few as four) lateral rays with the central ray one-celled and equal to or shorter than lateral rays in S. dimidiatum], the larger prickles on the stems and leaves (up to 15 mm in S. perplexum versus up to 6.5 mm in S. dimidiatum), and the larger leaves (up to 22 × 18 cm in S. perplexum versus up to 16 × 10 cm in S. dimidiatum).
Solanum perplexum occurs mainly in the region where the borders of Alabama, Florida, and Georgia meet, with a single outlying population known from western Mississippi.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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