This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol2", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
E. hypericifolia var. hirsuta Torr. Fl. N. & Mid. St. 331. 1826. Not E. hirsuta Schur, 1853.
Euphorbia hirsuta Wiegand, Bot. Gaz. 24: 51. 1897.
Annual, more or less hirsute. Stems branched at the base, the branches prostrate or decumbent, 2'-10' long, dichotomous, zigzag; leaves ovate-oblong, 4"-8" long, acutish. serrulate nearly to the oblique base, pale beneath; petioles about 1 long; stipules lacerate; peduncles surpassing the petioles; involucres funnel-form, 1/2" high, glabrous, bearing 4 stalked saucer-shaped dark-brown glands, each subtended by white crenate appendages; capsule about 1" in diameter, broader than long, glabrous, refuse at the apex, its angles obtuse; seed slightly more than i" long, 4-angled, black with a white coating, its faces even or slightly wrinkled.
Annual, glabrous or sparingly pubescent. Stem branched, at least above, ascending or erect, 7'-2° high, the branches mostly spreading, often recurved at the ends; leaves opposite, oblong, or linear-oblong, varying to ovate or obovate, often falcate, oblique, 3-nerved, unequally serrate, often with a red blotch and red margins, short-petioled; stipules triangular, slightly lacerate; involucres narrowly obovoid, 1/2" long, one-half or one-third as long as the peduncles, bearing 4 glands subtended by orbicular or reniform entire white or red appendages; capsule glabrous, 1" in diameter; seeds oblong-ovoid, 3/4" long, 4-angled, with broken transverse ridges.