Two points are very striking. By far the greatest part of the ordinary
garden-varieties differ from their species by a single sharp character
only. In derivative cases two, three or even more such characters may be
combined in one variety, for instance, a dwarfed variety of the larkspur
may at the same time bear white flowers, or even double white flowers,
but the individuality of the single characters is not in the least
obscured by such combinations.
The second point is the almost general occurrence of the same variety in
extended series of species. White and double flowers, variegated leaves,
dwarfs and many other instances may be cited. It is precisely this
universal repetition of the same character that strikes us as the
essential feature of a variety.
And again these two characteristics may now be considered separately.
Let us begin with the sharpness of the varietal characters. In this
respect varieties differ most obviously from elementary species. These
are distinguished from their nearest allies in almost all organs. There
is no prominent distinctive feature between the single forms of _Draba_
[125] _Verna_, _Helianthemum_ or of _Taraxacum_; all characters are
almost equally concerned. The elementary species of _Draba_ are
characterized, as we have seen, by the forms and the hairiness of the
leaves, the number and height of the flower-stalks, the breadth and
incision of the petals, the forms of the fruits, and so on.
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