Compilation
Heliotropium constrictum

Erect annual or sometimes perennial herb, 15–35 cm. high; stem and branches ± angular, subterete to the base, strigose. Leaves alternate; petiole 0.5–3.0(9) mm. long, strigose; lamina 10–35(50) x 1–6(9) mm., linear-lanceolate, strigose on both surfaces, apex and base acute, margins entire usually slightly revolute. Cymes simple, often numerous, lax, 4–10(14) cm. long when wholly expanded, terminal; rhachis strigose; bracts like the leaves, the lower ones 5–11 x 1–3 mm., gradually smaller to the cyme end. Flowers with pedicels 0.3–0.5 mm. long, a little accrescent, angular, decurrent on the rhachis. Calyx 1.5–2.5 mm. long, lobes ovate-lanceolate, ciliate, strigose outside, glabrous or subglabrous inside, persisting after the nutlets are shed. Corolla 2.5–3.5(4) mm. long, infundibuliform, strigose on the upper 2/3 outside, glabrous inside except for 5 tufts of small flattened hairs at the level of anther tips, white or with orange-yellow tube; lobes 0.5–1.0 x 0.7–1.5 mm., very widely triangular-ovate, obtuse or rounded, erect. Stamens inserted near the base on the corolla tube, anthers 0.7–0.8 mm. long, ovate-lanceolate, cohering by the minutely pubescent tips; filaments 0.2–0.3 mm. long. Ovary glabrous; style 0.2–0.4(0.5) mm. long, glabrous; stigmatic ring c. 0.4 mm. in diam.; sterile appendix 0.2–0.5 mm. long, narrowly conical. Fruit up to 1.4 x 2.2 mm., depressed, shortly strigose on the upper 1/2 or 2/3, late splitting into 4 free nutlets; nutlets ovoid, dark brown to black when mature, rounded on the back, with a deep central-peripheric hollow on each of the inner surfaces.