United States of America. “Amer. bor.”, C.S. Rafinesque s.n. [ex Herb. Rafinesque] (neotype, designated here: W [acc. # 0009388]).

Annual herbs to subwoody perennial shrubs up to 1.0 m tall, branching at base. Stems terete to ridged, green colour, pubescent with simple, appressed, uniseriate eglandular 1–5-celled trichomes, these ca. 0.2 mm long, new growth more densely pubescent. Sympodial units difoliate, not geminate. Leaves simple, 4.5–10.5(-17.5) cm long, 2.0–6.3(-8.3) cm wide, ovate, thin membranous, slightly discolorous, green above and purplish tinged underneath, especially so in younger growth; adaxial surface glabrous to sparsely pubescent with appressed translucent, simple, uniseriate trichomes like those on stem scattered mainly along veins; abaxial surface glabrous to sparsely pubescent with trichomes like those of the upper surface on both lamina and veins; primary veins 4–6 pairs; base attenuate to acute; margins sinuate dentate, rarely entire; apex acute to acuminate; petiole 1.0–5.0 cm long, pubescent with simple uniseriate trichomes like those of the stems. Inflorescences 1.0–2.5 cm long, lateral, internodal, unbranched or occasionally forked, with (2)3–6 flowers clustered near the tips (sub-umbelliform), sparsely pubescent with appressed simple uniseriate trichomes like those on stem; peduncle 1.0–1.7 cm long, straight; pedicels 8–10 mm long, 0.4–0.5 mm in diameter at the base and 0.5–0.6 mm in diameter at the apex, straight and spreading, articulated at the base; pedicel scars spaced ca. 0–0.5 mm apart. Buds subglobose, corolla exserted from the calyx to 1/3 of its length. Flowers 5-merous, all perfect. Calyx tube 0.7–0.9 mm long, the lobes 0.8–2.2 mm long, 0.7–1.3 mm wide, ovate to elongate with obtuse apices, sparsely pubescent with appressed hairs like those on stem but shorter. Corolla 8–10 mm in diameter, stellate, white with a yellow-green central portion near the base, lobed 1/3 to the base, the lobes 3.0–4.0 mm long, 1.0–1.2 mm wide, strongly reflexed at anthesis, later spreading, densely pubescent abaxially along margins and apex with simple uniseriate trichomes like those on stem and leaves but shorter. Stamens equal; filament tube minute, pubescent with spreading uniseriate simple trichomes adaxially; free portion of the filaments 0.6–1.0 mm long, pubescent like the tube; anthers (1–)1.5–1.7 mm long, 0.4–0.5 mm wide, ellipsoid, yellow, poricidal at the tips, the pores lengthening to slits with age. Ovary globose, glabrous; style 3.5–4.5 mm long, not exceeding anthers, densely pubescent with 2–3-celled simple uniseriate trichomes along 1/3 to 1/2 from the base; stigma capitate, minutely papillate, green in live plants. Fruit a globose berry, 6–8 mm in diameter, dull purplish-black at maturity, opaque, the surface of the pericarp matte to slightly shiny; fruiting pedicels 8–10 mm long, 0.4–0.6 mm in diameter at the base, 0.7–1.0 mm in diameter at the apex, recurved to reflexed, pedicels spaced 0.5–2.5 mm apart, dropping with mature fruits; fruiting calyx somewhat accrescent, the tube less than 1 mm long, the lobes 1.0–2.2 mm long, appressed to the surface of the berry or slightly spreading in mature fruit. Seeds 20–50(–60) per berry, 1.6–1.8 mm long, 1.0–1.2 mm wide, flattened and tear-drop shaped with a subapical hilum, brown, the surfaces minutely pitted, the testal cells pentagonal in outline. Stone cells 6–9(10) per berry, ca. 0.3 mm in diameter. Chromosome number: 2n=2×=24 (Stebbins and Paddock 1949, as S.americanum; Mulligan 1961, as S.americanum; Soria and Heiser 1961, as S.americanum; Heiser et al. 1965, as S.americanum; Edmonds 1983, as S.americanum; Crompton and Bassett 1976, as S.americanum).

(Figure 17) Solanumemulans is endemic to North America and is the most common species of black nightshade in eastern North America east of the Rocky Mountains from Maine to North Carolina and into Canada. Plants collected near Vancouver (British Columbia) may have been introduced along the railways.

Common in disturbed habitats such as riverbanks, gardens, rocky outcrops between sea level and 1,120 m elevation.

Canada. Eastern black nightshade, morelle noire de l’est (Bassett and Munro 1985, as S.ptychanthum); crêve-chien; tue-chien (Québec, Marie-Victorin et al. 3942). United States of America. American black nightshade (USDA Plants 2017, as S.ptychanthum), Eastern black nightshade (Ogg et al. 1981; Uva et al. 1997, both as S.ptychanthum). The common name of “West Indian nightshade” recorded in USDA Plants (2017) for this plant certainly refers to S.americanum.

Strausbaugh and Core (1979, as S.americanum) record the use of “ripe berries cooked and eaten in pies” in West Virginia. See also introductory section on Uses.

Least Concern (LC). Solanumemulans is common and weedy in the eastern United States and Canada. For EOO see Table 6.

Solanumemulans can be distinguished from other morelloids in North America by the small anthers 1.0–1.5 mm long, relatively long filaments 0.6–1.0 mm compared to S.americanum, calyx lobes longer than S.americanum and these appressed in fruit rather than strongly reflexed like in S.americanum, pedicel thickened at the apex in fruit (unlike in S.americanum), and pedicels that drop off with mature fruits (pedicels remain on the inflorescence in S.americanum). Solanumemulans has always 4–9(10) stone cells in fruits, while S.americanum either lacks or has maximum of 4 stone cells.

Solanumemulans can be distinguished from S.interius and S.nigrescens by its shorter anthers, usually shorter calyx lobes, and usually unbranched inflorescences. When sympatric with the occasionally introduced S.nigrum, S.emulans can be easily distinguished based on anther length and the numerous stone cells in the berries, but S.emulans also generally has thinner leaves that are often purplish tinged beneath. In the Great Plains, the morphologically similar S.interius becomes more common than S.emulans, while along the southern East and Gulf coasts in the United States of America S.americanum becomes more common. Solanumemulans is not known from the Caribbean.

Although S.emulans appears to have been in cultivation in European botanical gardens since the 18^th century, it has not escaped and naturalised beyond where it has initially been introduced. The few European specimens are from areas near oil and clothing factories and have apparently not persisted (Polgár 1926).

Constantine Rafinesque cited no specific specimens in his many descriptions of new taxa, and any herbarium he kept in North America was widely dispersed after his death and is thought to have been destroyed (Pennell 1944; Warren 2004). A specimen in the Vienna herbarium (W acc. #0009388) corresponding to the description of S.emulans and labelled “Solanum Virginicum/Amer. Bor. Rafinesque” and the date 1828 may be original material for this name. We have here selected this as a neotype, since there is no evidence in the protologue that this (or any other) specimen was used by Rafinesque to describe S.emulans.

The name S.ptychanthum has been used for this species in North America (e.g., Schilling 1981; Voss et al. 1993; Jones 2005), but the type of that name corresponds to a plant of S.americanum (see S.americanum description). Solanumemulans was long ignored, but in the protologue Rafinesque clearly refers to a taxon from “New England and Kentucky” that people were calling “S.virginicum” – probably the Linnaean S.nigrumvar.virginicum, not S.virginicum L. (an illegitimate name and orthographic variant of the spiny solanum from India S.virginianum L., see Jarvis 2007) – and his description matches this widespread small-flowered morelloid from eastern North America. The protologue states “NE states, usually mistaken for S. Virg.[virginianum] but smooth smaller, fl. white small, berries pisiform”. Specimens corresponding to this taxon are in the Dillenian herbarium in OXF under the polynomial (Solanumnigrum vulgari simile, caulibus exasperatis Dill. elth. 368, t. 275, f. 256) and correspond to the plate that was the only element cited for Solanumnigrumvar.virginicum (Linnaeus 1753).

D’Arcy (1974a) cited “Hungary, Polgar s.n. (MPU)” as the type of Solanumadventitium, but without specifying a locality or number. We do not consider this specific enough to constitute the citation of a single unambiguous specimen and it is likely to be in conflict with the protologue; we therefore lectotypify S.adventitium here. In the protologue of S.adventitiumPolgár (1926) cited several of his own collections made at “Meller’schen Ölfabrik” and “Güterbahnhof” (both in Györ, Hungary) between 1915 and 1919, but cited neither numbers nor herbaria. He noted that the plants had disappeared from both localities by October 1919, but again cited no herbarium. His herbarium is kept at BP, and we have selected one of his many collections labelled as S.adventitium in that herbarium collected between 1916 and 1919 from the freight depot in Györ as the lectotype (BP-352743).

See Suppl. materials 1 and 3.