Peanut, a leguminous plant, arachis hypo-gcea, also called ground pea and ground nut, and in some of the southern states known as pindar and gouber; by the French it is called arachide and pistache de terre. The genus arachis (a name of unknown origin) comprises seven species, six of which are natives of Brazil, and one, the peanut, is of doubtful nativity, being very generally cultivated in tropical countries; some regard it as indigenous to western Africa. The plant is a diffusely branched trailing annual, with abruptly pinnate leaves with four leaflets; the small yellow flowers are in axillary heads or spikes; calyx with one narrow lobe making a lower lip, the upper lip four-toothed, and with a long threadlike tube; keel of the corolla incurved and pointed; stamens united into a tube by their filaments, each alternate anther shorter than the others; ovary at the bottom of the long calyx tube; after the flower falls away, the forming pod is forced into the soil by the elongation of the rigid deflexed stalk to which it is attached; this stalk is not manifest at flowering time, but appears later, and curves in such a manner as to push the young pod quite below the surface; if by any accident this is prevented, the fruit ceases to grow, but when covered with earth it rapidly enlarges and forms a thick-shelled, indehiscent pod with a strongly netted surface, an inch or more long, often contracted between the seeds, of which it contains two or three; these have very thick cotyledons and an extremely short radicle.
This nut is of great commercial importance; immense quantities are produced on the W. coast of Africa to supply the European demand; it is largely cultivated in South America, and in our southern states from Virginia southward it is an important crop. For its • culture in this country good corn land is selected, which should not be of a reddish color, as that stains the shells and diminishes the price; the land is marked off in furrows 3 ft. apart, and in these two peas, deprived of their shells, are dropped at intervals of 18 in., and covered an inch and a half deep; the crop is cultivated until the pods begin to form, when it is laid by. Harvesting is done after the first frost; the vines are dug with pronged hoes, allowed to lie two days to dry, and then stacked or taken to a shed to cure; in about two weeks the peanuts are picked from the vines, rejecting the "pops," as the empty pods are called, and cleaned for market; picking is slow work, as an expert hand can pick only about three bushels a day; a machine has been used for this work with fair success.
The pods are cleaned by the use of a fanning mill, and as the price much depends upon their bright appearance, they are sometimes placed in a revolving cylinder where they are polished by mutual attrition; and the very white pods are made so by the use of the fumes of burning sulphur to bleach them. A good crop is 100 bushels to the acre, and it is regarded as more profitable than cotton or tobacco. Two varieties are recognized, the Virginia, which is the larger, and the Carolina or African. The vines when properly harvested, before there has been too much frost, are considered of equal value as food for animals with any other forage crop. Large quantities of peanuts are eaten, usually roasted; but their chief use is for making oil, the seeds containing from 42 to 50 per cent, of a nearly colorless, bland, fixed oil, resembling olive oil and used for similar purposes; the best is obtained by cold expression, but a larger quantity of inferior oil is procured by heating the seeds before pressing; it is a non-drying oil, changing but slowly by exposure to the atmosphere, and remaining fluid in a cold several degrees below 32° F. It contains, besides oleic and palmitic acids, two other oily acids, which have been called the arachic and hypogaeic, though it is doubtful if they are really distinct.
The principal consumption of the oil is in soap making. In the year 1867 there were imported into Marseilles alone, from Africa, more than 6,000,000 bushels, valued at over 25,000,000 francs. The seeds are also used in the manufacture of chocolate. The peanut may be cultivated in northern gardens by those who wish to witness its curious habit of pushing the pods under ground to ripen, though they will not come to perfection.
Peanut (Arachis hypogaea).