Heliotropium curassavicum L.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Glabrous perennial with scattered stems from stout creeping roots, somewhat fleshy, prostrate or decumbent, 2–5 dm; lvs linear or linear- oblanceolate, 1–4 cm × 2–5 mm; spikes seldom over 5 cm, the terminal ones usually paired on a peduncle, the lateral usually solitary and sessile or nearly so; cor 2–3.5 mm wide, white with a yellow eye; mature cal spreading; fr depressed-ovoid, 1.5–2.5 mm, soon splitting into 4 nutlets; 2n=26, 28. Native of tropical Amer., established as a weed, especially in saline soil, in s. U.S. n. to Del. and occasionally as a weed farther n. May–Sept. Ours are var. curassavicum. The well marked var. obovatum A. DC. (H. spathulatum) of interior w. U.S., with broader, more oblanceolate or even oblate lvs 6–18 mm wide and with the cor 5–9 mm wide, often with a purple eye, may possibly extend to w. Minn.