But the varieties each seem to have a
separate origin, as with apples, and the wide range of form and of taste
must have been present in the wild state, long before cultivation. Only
recently has the improvement of cherries, plums, currants and
gooseberries been undertaken with success by Mr. Burbank, and the
difference between the wild and cultivated forms has hitherto been very
small. All indications point to the existence, before the era of
cultivation, of larger or smaller numbers of elementary species.
The same holds good with many of the larger forage crops and other
plants of great industrial [80] value. Clover exhibits many varieties,
which have been cultivated indiscriminately, and often in motley
mixtures. The flower heads may be red or white, large or small,
cylindric or rounded, the leaves are broader or narrower, with or
without white spots of a curious pattern. They may be more or less hairy
and so forth. Even the seeds exhibit differences in size, shape or
color, and of late Martinet has shown, that by the simple means of
picking out seeds of the same pattern, pure strains of clover may be
obtained, which are of varying cultural value. In this way the best
subspecies or varieties may be sought out for separate cultivation. Even
the white spots on the leaflets have proved to be constant characters
corresponding with noticeable differences in yield.
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