Shrubs or trees, 2-12 m high, unarmed. Trunks to 10 cm in diameter; bark pale to dark brown; young branches slightly sulcate, yellowish granular-tomentose, the older stems glabrescent, the hairs porrect-stellate, echinoid, and dendritic-echinoid, sessile or with thin stalks up to 0.3 mm long.
Sympodial units plurifoliate, axillary leaves present or lacking, if present lanceolate, elliptic or ovate-orbicular.
Leaves simple, the blades mostly 10-24 x 2.5-7.8 cm, ca. 3.5-4 times as long as wide, elliptic to oblong-lanceolate, relatively thin, grayish to dark green, velutinous to scabridulous adaxially, the hairs porrect-stellate, multangulate, and echinoid, touching to overlapping, sessile or with stout stalks to 0.1 mm long, pale green to gray tomentose abaxially, the hairs porrect-stellate, multangulate, and echinoid, sessile or with thin or thick stalks up to 0.4 mm long; main lateral veins 11-15 on each side of midrib; base obtuse, acute or cuneate, or if attenuate then blades decurrent only 1/2 cm or less; margin entire; apex long attenuate or acuminate; petioles 1-4.2 (-6.2) cm long, granular-tomentose, the hairs mostly multangulate, echinoid, and dendritic-echinoid, sessile or with thin stalks up to 0.5 mm long.
Inflorescences 6-16 cm long (8.5-22 cm in fruit), pseudoterminal, many times branched, with ca. 60-250 flowers, granular-tomentose, the hairs porrect-stellate, echinoid, and dendritic-echinoid, sessile or with thin stalks up to 1.9 mm long; peduncles 6.7-15 x 0.2-0.4 cm; rachis 0.7-2.1 cm; pedicels 1.3-4 mm, 3.7-7 mm in fruit, closely spaced 1.1-3.1 mm apart, articulated at the base, tomentose, becoming less so with age, the hairs porrect-stellate, multangulate, and echinoid, sessile or with thin stalks up to 0.9 mm long.
Buds 5-7.5 mm long at anthesis, orbicular; corollas tomentose, the hairs porrect-stellate and multangulate, sessile or with thin stalks up to 0.8 mm long; calyx lobe sutures usually obscured by tomentum. Flowers all apparently perfect. Calyx subcampanulate, 3.7-6.3 mm long, the tube 2-3.8 mm, lobed ca. ½-2/3 way to base, the lobes 1-2.5 x 1.4-2.6 mm in flower, the lobes acute, relatively thick, the midveins often prominent, tomentose abaxially, the hairs porrect-stellate, multangulate, echinoid, and dendritic-echinoid, sessile or with thin stalks up to 0.5 mm long, glabrous adaxially; fruiting calyx accrescent, pubescence as in flower, but the hairs of the abaxial surface with thicker stalks up to 1 mm long, the lobes 1.9-5.8 x 2.9-4.7 mm. Corolla 1.2-2 cm in diameter, 8.1-18 mm long, early exserted ca. length of calyx or its lobes at anthesis, stellate, pale violet to purple, the tube 1.9-4.2 mm, the lobes 4-13 x 2.6-5.9 mm, ovate-lanceolate, abaxially with pubescence as in bud but occasionally with echinoid hairs as well, glabrous adaxially or with hairs on upper quarter and along midveins, the hairs when present simple, 0.2-0.5 mm long on midvein and sessile porrect-stellate at the lobe tips. Stamens with filaments 0.8-1.4 mm long, inserted on corolla tube 0.9-1.2 mm above base, glabrous; anthers 3-4.9 x 0.9-1.4 mm, oblong, blunt-tipped, yellow, drying dark brown on the abaxial surface, free, poricidal at the tips, the pores directed distally and somewhat adaxially, farinose around edges, lengthening to longitudinal slits with age. Ovary subspherical, tomentose, the hairs sessile, appressed, multangulate and echinoid; style 4.8-7.6 x 0.2-0.3 mm, exserted from stamens, cylindrical, sparsely pubescent 1/2-3/4 way from base, the hairs sessile or with thin stalks up to 0.2 mm long, porrect-stellate; stigma elongate, to 1.4 mm long, the apex rounded or blunt-tipped.
Fruit a fleshy berry, 1-1.7 cm in diameter, globose, yellow to brownish when ripe, farinose or tomentose, the hairs sessile, appressed, multangulate and echinoid.
Seeds 1.7-2.8 x 1.5-2.3 mm, sublenticular to deltoid, yellow to orangish-tan, the surface reticulate-punctate.
Widespread from southern Brazil ranging westward to the Chaco region of the Paraná river in Paraguay and southward in Uruguay and eastern Argentina from sea level to 1000 m. Solanum granuloso-leprosum is occasional to common in secondary thickets of scrub forest and savannahs in warm temperate, subtropical, and tropical regions.