Solanum triquetrum Cav., texas nightshade, hierba mora. Perennial herb, rhizomatous with upright, belowground axes to 100 mm long, clump–forming, fibrous–rooted, not rosetted, ascending to erect, in range to 115 cm tall, to 300 cm across; shoots with only cauline leaves, axes and foliage essentially glabrous.
Stems initially ± 3–angled, to 3 mm diameter, with 2 ridges descending from each leaf, green with minutely dotted (stomates), woody basal stems with tannish periderm having longitudinal splits
Leaves helically alternate, simple, petiolate, without stipules; petiole ± hemicylindric, to 8 mm long, indistinct from blade; blade deltate to triangular or narrowly triangular, to 30 × 15 mm, truncate, cordate, or tapered at base, if present basal lobes rounded, entire, acute to rounded (notched) at tip, pinnately veined with principal veins somewhat raised on both surfaces, sparsely short–hairy and with minute glandular hairs.
Inflorescence cyme, forking with vegetative shoot, 4—6–flowered, often with 2 flowers at each fork, glabrous; peduncle at anthesis to 15 mm long; bractlet absent; pedicel with conspicuous, cup–shaped swelling at base and purplish to green, cylindric above swelling, at anthesis 7—8 mm long and becoming wider approaching flower, glabrous with scattered, minute glandular hairs, abscising above swelling.
Flower bisexual, radial, 11—15 mm across; calyx 5–lobed, outer surface with scattered, minute glandular hairs; tube funnel–shaped, 2—2.5 mm long, green or aging with purple at sinuses and tips in fruit often purple, somewhat membranous at sinuses by stretching; lobes ascending, triangular or fingerlike above midpoint, 1.5—2 mm long increasing in fruit, green often with purple, acute to obtuse at tips, upper surface and margins minutely puberulent; corolla 5–lobed, white, in bud white and green including pale green veins; tube wide funnel–shaped, 7—8 × 3—3.3 mm, 3—3.5 mm wide at orifice, lower portion green, above pale green star pattern into lobes, pleated at sinuses; lobes spreading, acute–ovate, in range white, papillate–hairy mostly close to margins and tips; stamens 5, fused to corolla at base in ring ca. 0.7 mm long; filaments 1—1.5 mm long, white; anthers touching, basifixed, dithecal, 3—4 mm long, bright yellow but paler on inner sides, dehiscent by 2 terminal pores and orange around pores, sacs subequal or 1 shorter; pollen white; nectary disc absent; pistil 1, 7.5—8 mm long; ovary conic–ovoid, ca. 1.5 × 1 mm, light green, glabrous, 2–chambered, each chamber with many ovules attached to center; style straight, whitish to greenish, unbranched; stigma exserted 2—3 mm above anthers, oblique at tip, green, papillate.
Fruit berry, many–seeded, spheroid, 7—10.5 mm, black to dark red, glabrous; pulp thin.
Seed ± kidney–shaped compressed side–to–side, 2.7—3.2 × 2—2.2 mm, yellowish.
A. C. Gibson