All of our specimens except one are from the southern half of the state. We have, however, three reports from the northern half. It is to be noted that this species is separated with difficulty from Euphorbia supina and this similarity may result in their confusion. In the field Euphorbia humistrata is notably more glaucous than Euphorbia supina.
Much like no. 31 [Euphorbia maculata L.]; sometimes rooting at the lower nodes; lvs pale green, chiefly obovate to obovate-oblong, or narrower on the smaller branches, mostly 5-15 mm and more than half as wide, commonly widest above the middle, inconspicuously serrulate; involucre cleft on one side for fully half its length (this the most dependable distinction from no. 31); styles 0.5-0.7 mm; seeds smooth or nearly so. Moist alluvial soil; O. to Kans., s. to Ala. and Tex., and occasionally adventive farther e. Aug.-Oct. (Chamaesyce h.)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.