He has arrived at this conclusion from finding in the several varieties a perfect gradation between the most extreme characters; so perfect is this gradation that he maintains it to be impossible to classify the varieties by any natural method. M. Decaisne raised many seedlings from four distinct kinds, and has carefully recorded the variations in each. Notwithstanding this extreme degree of variability, it is now positively known that many kinds reproduce by seed the leading characters of their race. (10/99. 'Gardener's Chronicle' 1856 page 804; 1857 page 820; 1862 page 1195.)
STRAWBERRIES (Fragaria).
This fruit is remarkable on account of the number of species which have been cultivated, and from their rapid improvement within the last fifty or sixty years. Let any one compare the fruit of one of the largest varieties exhibited at our Shows with that of the wild wood strawberry, or, which will be a fairer comparison, with the somewhat larger fruit of the wild American Virginian Strawberry, and he will see what prodigies horticulture has effected. (10/100. Most of the largest cultivated strawberries are the descendants of F. grandiflora or chiloensis, and I have seen no account of these forms in their wild state. Methuen's Scarlet (Downing 'Fruits' page 527) has "immense fruit of the largest size," and belongs to the section descended from F. virginiana; and the fruit of this species, as I hear from Prof. A. Gray, is only a little larger than that of F. vesca, or our common wood-strawberry.) The number of varieties has likewise increased in a surprisingly rapid manner. Only three kinds were known in France, in 1746, where this fruit was early cultivated. In 1766 five species had been introduced, the same which are now cultivated, but only five varieties of Fragaria vesca, with some sub-varieties, had been produced. At the present day the varieties of the several species are almost innumerable. The species consist of, firstly, the wood or Alpine cultivated strawberries, descended from F. vesca, a native of Europe and of North America. There are eight wild European varieties, as ranked by Duchesne, of F. vesca, but several of these are considered species by some botanists. Secondly, the green strawberries, descended from the European F. collina, and little cultivated in England. Thirdly, the Hautbois, from the European F. elatior. Fourthly, the Scarlets, descended from F. virginiana, a native of the whole breadth of North America. Fifthly, the Chili, descended from F. chiloensis, an inhabitant of the west coast of the temperate parts both of North and South America. Lastly, the pines or Carolinas (including the old Blacks), which have been ranked by most authors under the name of F. grandiflora as a distinct species, said to inhabit Surinam; but this is a manifest error. This form is considered by the highest authority, M. Gay, to be merely a strongly marked race of F. chiloensis. (10/101. 'Le Fraisier' par le Comte L. de Lambertye 1864 page 50.) These five or six forms have been ranked by most botanists as specifically distinct; but this may be doubted, for Andrew Knight (10/102. 'Transact. Hort. Soc.' volume 3 1820 page 207.) who raised no less than 400 crossed strawberries, asserts that the F. virginiana, chiloensis and grandiflora "may be made to breed together indiscriminately," and he found, in accordance with the principle of analogous variation, "that similar varieties could be obtained from the seeds of any one of them."
Since Knight's time there is abundant and additional evidence (10/103. See an account by Prof. Decaisne, and by others in 'Gardener's Chronicle' 1862 page 335 and 1858 page 172; and Mr. Barnet's paper in 'Hort. Soc. Transact.' volume 6 1826 page 170.) of the extent to which the American forms spontaneously cross. We owe indeed to such crosses most of our choicest existing varieties. Knight did not succeed in crossing the European wood-strawberry with the American Scarlet or with the Hautbois. Mr. Williams of Pitmaston, however, succeeded; but the hybrid offspring from the Hautbois, though fruiting well, never produced seed, with the exception of a single one, which reproduced the parent hybrid form. (10/104.