This section is from the book "A Manual Of Weeds", by Ada E. Georgia. Also available from Amazon: A Manual Of Weeds.
Native. Annual. Propagates by seeds. Time of bloom: June to October. Seed-time: July to November.
Range: Throughout the American Continent except the far North. Habitat: Gardens, fields, roadsides. Found in all crops, but most common in dry soil of low fertility.
Of all the Spurges, this one seems the most hardy and adaptable, able to grow anywhere and to endure any hardship; it often appears from the cracks of flags and paving stones in cities, and flourishes while being trodden under foot. From such a place the writer pulled the thrifty specimen from which this description is written. Every part of it, even the root, exudes a poisonous milky juice which will irritate the skin to a red rash or in a short time blister it. Apparently nothing eats the weed, even insects leaving it untouched. (Fig. 187.)
It has rather long, branching, and fibrous roots, with many fine feeding rootlets. Stem round, slender, finely hairy, prostrate, three inches to a foot or more in length, with numerous branches extended in all directions, red where exposed to the light but green underneath. Leaves opposite, oblong, from a quarter-inch to nearly an inch in length, short-petioled, very finely toothed, usually with a purplish brown spot near the center; stipules nearly linear, tipped with a fringe of bristles. Flowers on peduncles about as long as the petioles, the involucres bearing four minute, cup-shaped glands with narrow red appendages. Pods angled and hairy, with ash-gray, four-angled seeds which are a frequent impurity in the seeds of grass and clover.
In cultivated ground, persistent hoe-cutting as soon as the first flowers appear. Grasslands badly infested should be put under cultivation, the ground being fertilized well before reseeding heavily to grass or clover.