Page:Popular Science Monthly Volume 82.djvu/344

340 As one of the first experimenters stated, "a sickness takes hold of the vines and they die." The agent causing the sickness is the phylloxera, a tiny plant louse, undiscovered until the last half of the nineteenth century, which works on the leaves and roots of the European grapes, but which does comparatively little harm to American species. Undoubtedly, the resistance of native grapes to the phylloxera is due to natural selection in the contest that has been going on for untold ages between host and parasite. Three other pests, black-rot, downy mildew and powdery mildew, are destructive to European grapes in America. The climate, too, in eastern North America alternates between hot and cold, wet and dry, and the Old World grapes grow well only in equable temperatures and conditions of humidity. The leaves of the Old World grape are thin and soft and the roots fleshy; the leaves of the American species are thick and leathery and the roots hard and fibrous. These differences in the structure of the species of Vitis explain their adaptations to the two climates.

That American viticulture must depend upon the native species for its varieties began to be recognized at the beginning of the nineteenth century, when several large companies engaged in growing foreign grapes failed, and a meritorious native grape made its appearance. The vine of promise was a variety known as the Alexander. Thomas Jefferson, ever alert for the agricultural welfare of the nation, writing in 1809 to John Adlum, one of the first experimenters with an American species, voiced the sentiment of grape experimenters, in speaking of the Alexander:

The Alexander is an offshoot of the common fox grape, Vitis Idbrusca, found in the woods on the Atlantic coast from Maine to Georgia and occasionally in the Mississippi Valley. The history of the variety dates back to just before the Revolutionary War, when, according to William Bartram, the Quaker botanist, it was found growing in the vicinity of Philadelphia, by John Alexander, gardener to Governor Penn of Pennsylvania. Curiously enough, it came into general cultivation through the deception of a nurseryman. Peter Legaux, mentioned before, in 1801 sold the Kentucky Vineyard Society fifteen hundred grape cuttings, which he said had been taken from an European grape, introduced from the Cape of Good Hope, therefore, called the "Cape" grape. Legaux's grape turned out to be the old Alexander. In the new home the spurious "Cape" grew wonderfully well and as the knowledge of its fruit fulness in Kentucky, Ohio and Indiana spread, demand for it increased and with remarkable rapidity, considering the time, it came into general cultivation in the parts of the United States then settled.

Of the several species of American grapes now under cultivation,