llfedicine.—Sunflower seed also has some medici nal use. When ground and mixed with other food products and fed to animals it improves their digestion and keeps them in good physical condi tion. The ground seed is said to be used exten sively as an important constituent of condition powders and stock-foods.
Paper and fiber.—Sunflower stems are used for fuel, though they would make excellent paper stuff and yield a fine fiber if industries were developed thus to utilize them.
Commercial status of the crop.
Up to this time sunflower seed has been used mainly for poultry food and in the manufacture of stock-food. For these purposes the limited amount grown has usually found a ready sale at an aver age price of about two cents per pound. Sunflow ers may be grown at about the same cost per acre as corn, but by the methods now employed the har vesting and threshing of sunflower seed is a rather slow and expensive process, and until better meth ods and improved machinery for handling the crop are secured, it is not practicable to grow sunflow ers on a large scale.
Literature. • The best publication on the sunflower which the writer has seen is Bulletin No. 60 of the Division of Chemistry, United States Department of Agri culture. This bulletin has been used in the prepa ration of this article.
Ipomeea Batatas, Poir. (Con volvus, Batatas, Linn. Batatas edulis, Choisy.) Convolvulacea. Figs. 838-847.
The sweet-potato is an edible tuberous root, much valued in this country, especially in the southern states, where it is a staple. It is used chiefly for human food as a table vegetable, for canning and for pies. It is more valuable for stock-food than the Irish potato because of its high content of fat, sugar (4-6 per cent) and starch (16-18 per cent). Hogs can be turned in the patch and will root out the sweet-potatoes for themselves. The sweet-potato is sometimes fed to cattle and horses, for which purpose it is sliced.
This plant belongs to the morning-glory family. The trailing vine closely resembles some of the wild species, especially Iportura pandurata, and it is difficult to distinguish the latter when it grows as a weed in the sweet-potato patches. The flowers, which are rarely produced in the North, resemble very closely those of the common varieties of morning-glory, but are smaller. The leaves are ovaL!-cordate, usu ally angular or lobed, petioled and exceedingly varia ble ; the peduncles equal or exceed the petioles, several flowered, the corol las one to two inches wide. The
flowers are p u r - ' plish, 3 or 4 on each peduncle or branches of th e peduncle; stamens 5 ; pistil 1, ripening into a pod with four 1-seeded cells.
The nativity of the sweet-potato is unknown, but it is probably tropical America. It was cultivated in the tropics of both hemispheres when authentic records began. DeCandolle inclines to an American origin. The species Iponura Batatas is nowhere known in a wild aboriginal state ; it has been sug gested that it may be a derivative of some other species, as I. fastigiata. Safford saw models of the sweet-potato in the pre-historic Yunta graves of Ancon, Peru, which exhibited the pentagonal form often seen in certain varieties.
Distribution.
The sweet-potato is essentially an American crop, but it is now in cultivation in many of the islands of the Pacific. Some of the varieties in cultivation in the United States have come back from China. Commercially, the northern limit of sweet -potato -culture on the Atlantic coast of America is about the middle of New Jersey. This line, extended westward, barely takes in southern Ohio and Kansas. At Muscatine island in the Missis sippi river and in certain other warm, sandy soils from there southward, a few districts compete with the southern growers. Sweet-potato-culture practi cally disappears on the Rocky mountain plateau and the arid regions of the West, except in irri gated sandy soils far to the southward, as in southern New Mexico, Arizona and in California. The crop is grown extensively in southern Cali fornia under irrigation, both in the Imperial val ley and in the Los Angeles district. It is also grown under irrigation on some sandy soils of the lower San Joaquin, especially near Merced and At water, and to a limited extent at other points in the great interior valley of California. The crop does not appear to be adapted to the cool nights and dry atmosphere of the Rocky mountain plateau, or the great basin, or even in the higher parts of Arizona and California, in spite of the fact that the total heat is more than ample and the warm sandy soils supply ideal conditions, with irrigation water to maintain the soil moisture. Sweet-potato culture, therefore, even in the warm parts of arid America is pursued .commercially only at a few points. Sweet-potatoes may be grown in the north ern states by careful attention, but neither the quality nor the quantity of the crop is satisfactory when compared with that of the South.