Solanum viarum
Solanum nigrescens
tropical soda apple
divine nightshade
petiolate;
petiole 3–6 cm;
blade simple, ovate to suborbiculate, 7–10(–20) × 6–8(–15) cm, margins coarsely lobed with 3–5 lobes per side, lobe margins entire to coarsely toothed, base truncate to cordate.
petiolate;
petiole 0.5–2 cm;
blade simple, ovate to ovate-elliptic, 4–10.5 × 2–5 cm, margins entire or shallowly sinuate-dentate, base decurrent.
extra-axillary, sessile or nearly so, unbranched, 3–5-flowered.
extra-axillary or leaf-opposed, unbranched, umbel-like to racemelike, (2–)5–10-flowered, 1–3.5 cm.
0.7–1.1 cm in flower, 1–2 cm in fruit.
spreading and 0.5–1 cm in flower, spreading and 1–1.5 cm in fruit.
radially symmetric;
calyx somewhat accrescent, unarmed or sparsely prickly, 3–4 mm, densely pubescent, lobes triangular;
corolla greenish or whitish, stellate, 1.5–2.5 cm diam., without interpetalar tissue;
stamens equal;
anthers narrow and tapered, 5.5–7(–10) mm, dehiscent by terminal pores;
ovary densely pubescent, hairs glandular and eglandular.
radially symmetric;
calyx not accrescent, unarmed, 1–2 mm, sparsely pubescent, lobes deltate;
corolla white, rarely purplish, often with green or purplish central star, stellate, 1–1.5 cm diam., with sparse interpetalar tissue;
stamens equal;
anthers ellipsoidal, 2–3 mm, dehiscent by terminal pores that open into longitudinal slits;
ovary glabrous.
light green mottled with dark green when young, yellow when ripe, globose, (1.5–)2–3 cm diam., glabrous, without sclerotic granules.
dull green or purplish, globose, 0.5–0.8 cm diam., glabrous, with (4–)5–6(–13) sclerotic granules.
reddish brown, flattened, 2–3 × 2–2.5 mm, minutely pitted.
tan, flattened, 1.2–1.5 × 1–1.1 mm, finely pitted.
= 24.
= 24.
Solanum viarum
Solanum nigrescens
In the United States, Solanum viarum was first collected in Florida in 1988 and has subsequently become an aggressive and invasive species in the Southeast. It is on the Federal Noxious Weeds List and is classified as a noxious weed or plant pest in many states. Cattle and other animals eat the fruits and spread the seeds through their feces, and the seeds are coated with a sticky substance that makes them adhere to farm equipment when the plants are mowed. It can form large patches that are difficult to eradicate due to their extensive root systems and sharp prickles. It is a major agricultural pest and a threat to native ecosystems.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Solanum nigrescens is widespread in Central and northern South America and the Caribbean and extends northward into the southeastern United States along the Gulf Coast and slightly inland. Where sympatric with S. americanum, it can be distinguished by its longer anthers and dull green or purplish berries with appressed to spreading calyx lobes. Plants collected as weeds in rice and sugarcane fields of Louisiana and provisionally identified as the Chinese species S. merrillianum T. N. Liou are somewhat intermediate between S. americanum and S. nigrescens and could represent recent hybrid populations (S. Knapp et al. 2019). Solanum nigrescens differs from S. douglasii in its shorter anthers and longer filaments relative to anther length; moreover, S. douglasii is usually found west of the Rocky Mountains, whereas S. nigrescens occurs in the southeastern United States. The ranges of S. nigrescens and S. interius overlap (for example, in Texas). Solanum nigrescens may be distinguished from S. interius by its usually acute calyx lobes, smaller seeds, and more numerous sclerotic granules in the fruits. Solanum nigrescens differs from S. nigrum in its more slender peduncles and pedicels, smaller seeds, and fruits with sclerotic granules.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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