This section is from the book "Nature's Garden", by Neltje Blanchan. Also available from Amazon: Nature's Garden; An Aid To Knowledge Of Our Wild Flowers And Their Insect Visitors.
Flowers - (Apparently) white, small, borne in forked, long-stalked umbels, subtended by green bracts; but the true flowers are minute, and situated within the white cup-shaped involucre, usually mistaken for a corolla. Staminate flowers scattered over inner surface of involucre, each composed of a single stamen on a thread-like pedicel with a rudimentary calyx or tiny bract below it. A solitary pistillate flower at bottom of involucre, consisting of 3-celled ovary; 3 styles, 2-cleft, at length forming an erect 3-lobed capsule separating into 3 2-valved carpels. Stem: 1 to 3 ft. high, often brightly spotted, simple below, umbellately 5-branched above (usually). Leaves: Linear, lance-shaped or oblong, entire; lower ones alternate, upper ones whorled.
Preferred Habitat - Dry soil, gravelly or sandy.
Flowering Season - April - October.
Distribution - From Kansas and Ontario to the Atlantic.
A very commonplace and uninteresting looking weed is this spurge, which no one but a botanist would suspect of kinship with the brilliant vermilion poinsettia, so commonly grown in American greenhouses. Examination shows that these little bright white cups of the flowering spurge, simulating a five-cleft corolla, are no more the true flowers in the one case than the large red bracts around the poinsettia's globular greenish blossom involucres are in the other. From the milky juice alone one might guess the spurge to be related to the rubber plant. Still another familiar cousin is the stately castor-oil plant; and while the common dull purplish ipecac spurge (E. Ipecacuanhae) also suggests unpleasant doses, it is really a member of quite another family that furnishes the old-fashioned emetic. The flowering spurge, having its stami-nate and pistillate flowers distinct, depends upon flies, its truest benefactors, to transfer pollen from the former to the latter.