Among many other English names given to the sun spurge we find wartweed, sunweed, turnsole, churnstaff, cat's-milk, wolf's-milk.
The sun spurge is a smooth annual plant with an erect, stout stem from eight to twelve inches high, often branched from the base. The branches, as well as the main stem, end in a more or less compound umbel which is subtended by a circle of leaflets. The leaves are scattered along the stem; they are somewhat oblong or wedge-shaped, sometimes nearly round, from one-half to four inches long, finely saw-edged, and narrowed to a short stalk. The rather inconspicuous flowers are of two kinds, the staminate and pistillate on the same plant, both included in a cup-shaped involucre resembling a calyx or corolla. The staminate flowers are numerous, lining the inside of the cup, each consisting of one single stamen in the axil of a very little bract. The pistillate flower is solitary in the centre of the cup and consists of a three-lobed, three-celled ovary which soon protrudes on a long stalk and hangs over the brim of the cup-like involucre. The seeds are reddish-brown, strongly honeycombed. The plant is in bloom from June till October.
Introduced from Europe, the sun spurge has become common in east Quebec and Ontario, and is gradually spreading in Canada.
All species of Euphorbia or spurge contain a more or less poisonous milky juice, which is very acrid, and in contact with the skin causes extreme irritation, inflammation, vesication, and in some cases gangrene. The poisonous substances have not yet been fully investigated.
In regard to the spurges, H. C. Long says: "The caper spurge (E. Lathyrus L.) contains an acrid, emetic, and highly purgative milky juice, and the fruits have commonly been employed by country folk as a purge, and also as a pickle, though they are dangerous and should not be so used. Pratt records a case in which five women ate the pickled fruits with boiled mutton, and all suffered severe pain and burning in the stomach, and showed other symptoms attendant on irritant poisoning - and though all recovered the illness was severe. Used in this manner, indeed, they have given rise to serious cases of human poisoning. Sun spurge (E. Helioscopia L.) is similarly poisonous to the preceding species. It has caused fatal poisoning to a boy who ate it. In Germany, cows were poisoned through pasturing in stubble in which the plant was growing, but there were no deaths."
White, in his "Dermatitis Venenata," states in regard to the genus: "More than one hundred species of Euphorbia, or spurge, grow in the United States, either indigenous or immigrants from Europe. Of every species Loudon says the juice is so acrid as to corrode and ulcerate the body wherever applied; and of E. resinifera, from which the official euphorbium is obtained, Pliny and Dioscorides, according to the Dispensatory, describe the method of collecting juice, so as to prevent irritation of the hands and face. This substance is used as a plaster to prolong suppuration."
Van Hasselt states that "the juice of several species is used by quacks to remove warts, freckles, as depilatory, etc.; and that the application of the juice, powder, and extract produces not only erysipelatous, pustular and phlegmonous inflammation, but even gangrene. In one case mentioned the whole abdominal wall became the seat of gangrene."
According to Cornevin the spurges have an irritating effect on the mucous membrane, especially at the back of the mouth. In from three-quarters of an hour to two hours after eating the plant, or even longer, there is painful vomiting, followed by diarrhceic evacuations, with a lowering of the temperature. If the quantity ingested has been sufficient there appear also nervous symptoms, vertigo, delirium, muscular tremors and circulatory troubles which disappear after abundant sweating if the poisoning is not fatal. If it is fatal the symptoms of superpurgation and enteritis predominate, but are accompanied by nervous symptoms and circulatory disorders.
Mueller gives in addition loss of appetite, piteous whining (in goats), groaning, colic, and tympanites; and Pott, bloating, fever, palpitation of the heart, and loss of consciousness; cows gave a reddish or sharp-tasting milk. Milk of affected goats caused diarrhoea in human beings.
Remedy and Means of Control: The advice of a physician should be requested. As sun spurge is an annual plant it may be suppressed by preventing the development of the seeds. On cultivated land it should be cut off by the hoe before or as soon as the first flowers appear. Badly infested lands should be put under cultivation, well fertilized, and resown heavily to grass or clover.