Solanum americanum
Solanum umbelliferum
American black nightshade, American black or common or West Indian nightshade, glossy nightshade, little white nightshade, small-flower nightshade, white nightshade
blue nightshade, blue witch, blue witch or chaparral nightshade, bluewitch 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 0.2–1.5(–3) cm;
blade simple, lanceolate to ovate or obovate, (0.5–)1–4(–9) × 0.5–2(–6.5) cm, margins entire to pinnatifid with 1(–3) pairs of lobes at base, lobe margins entire to undulate, base attenuate to truncate, occasionally subcordate.
extra-axillary or leaf-opposed, unbranched, usually umbel-like, 3–10-flowered, 0.5–3 cm.
terminal or lateral, leaf-opposed or extra-axillary, simple or once-branched, 5–20-flowered, 1–8 cm.
erect or spreading, 0.3–1 cm in flower, to 1.5 cm in fruit.
inserted into small sleeve on inflorescence axis, 0.5–1.5 cm in flower, 1.2–2 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 slightly accrescent, unarmed, 2.5–5.5 mm, glabrous to densely pubescent, hairs unbranched or dendritic, lobes broadly deltate;
corolla pale to deep purple or occasionally white, with green spots edged with white at base of lobes, spots separate or confluent, rotate, (1–)1.3–2.5 cm diam., with abundant interpetalar tissue;
stamens equal;
anthers ellipsoidal, slightly tapered, 3.5–4.5 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.
green, greenish black, or black, globose, 1–2 cm diam., glabrous, without sclerotic granules.
pale yellow to brown, 1–1.5 × 0.5–1.5 mm, minutely pitted.
reddish brown, flattened, ca. 2 × 1.5 mm, minutely pitted.
= 24.
Solanum americanum
Solanum umbelliferum
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 umbelliferum is common in the western part of North America from Washington to Baja California. It is found throughout California except for Modoc Plateau, Desert Province, and Central Valley.
Past treatments have divided Solanum umbelliferum into a number of taxa based on leaf size and shape and pubescence type and density, but the most recent monograph (S. Knapp 2013) regarded it as one highly variable and widespread species in which no character discontinuities can be seen. Glabrous populations from northern California have been called S. parishii, sticky-glandular populations from central and southern California S. xanti, glabrous populations from southern California have been called var. glabrescens, and densely pubescent eglandular populations from central California have been called S. californicum Dunal. Island populations with larger leaves have been called S. clokeyi (but see 52. S. wallacei, a distinct endemic on Santa Catalina Island). A number of new varietal combinations were published by D. J. Keil (2018) to accommodate much of this regional and local variation, but the group needs thorough study using both molecular and morphological analysis across its range to assess the taxonomic validity of these segregants. Some of the variation may be environmental.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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