Solanum viarum
Prodr. 13(1): 240. 1852.
Shrubs, erect, sparsely armed, 0.5–2 m, prickles white or yellowish, straight or recurved, 1–25 mm, densely pubescent, hairs unbranched, short-glandular and longer-eglandular, with sessile, stellate hairs on abaxial leaf surface, these 4(–5)-rayed, central ray shorter than lateral rays. Leaves 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. Inflorescences extra-axillary, sessile or nearly so, unbranched, 3–5-flowered. Pedicels 0.7–1.1 cm in flower, 1–2 cm in fruit. Flowers 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. Berries light green mottled with dark green when young, yellow when ripe, globose, (1.5–)2–3 cm diam., glabrous, without sclerotic granules. Seeds reddish brown, flattened, 2–3 × 2–2.5 mm, minutely pitted. 2n = 24.
Phenology: Flowering May–frost (year-round in Fla.).
Habitat: Pastures, roadsides, disturbed areas.
Elevation: 0–1000 m.
Distribution
Introduced; Ala., Fla., Ga., La., Miss., N.C., Pa., S.C., Tenn., Tex., South America (Argentina, Brazil, Paraguay, Uruguay), introduced also in Asia (India), Africa.
Discussion
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.
Selected References
None.