Euphorbia nutans Lag.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Annual; stems to 8 dm, obliquely ascending at least in the upper half, the lower half often erect, the younger parts puberulent, often in a single longitudinal strip, with usually incurved hairs to 0.3 mm, the older parts glabrous or nearly so; lvs opposite, oblong or oblong-ovate, 1–3.5 cm, about a third as wide, serrulate, usually conspicuously inequilateral; fr 2–2.5 mm, strongly 3-lobed, glabrous; seeds gray or pale brown, 1–1.5 mm; 2n=12. Dry or moist soil; N.H. to Mich. and N.D., s. to Fla. and Tex.; abundant as a weed in lawns and gardens and intr. elsewhere in the world. June–Oct. (E. maculata, misapplied; E. preslii; Chamaesyce rafinesquii)