This experience probably gives an explanation [353] why the
quinquefoliolate variety is so seldom met with in the wild state. For
even if it did occur more often, the plants would hardly find
circumstances favorable enough for the full development of their
varietal character. They must often be so poor in anomalous leaves as to
be overlooked, or to be taken for instances of the commonly occurring
quadrifoliolate leaves and therefore as not indicating the true variety.
In the beginning of my discussion I have asserted the existence of two
different races of "four-leaved" clovers, a poor one and a rich one, and
have insisted on a sharp distinction between them. This distinction
partly depends on experiments with clover, but in great part on tests
with other plants. The previously mentioned circumstance, that clover
cannot be pollinated on a sufficiently large scale otherwise than by
insects, prevents trials in more than one direction at the same time and
in the same garden. For this reason I have chosen another species of
clover to be able to give proof or disproof of the assertion quoted.
This species is the Italian, or crimson clover, which is sometimes also
called scarlet clover (_Trifolium incarnatum_). It is commonly used in
Europe as a crop on less fertile soils than are required by the red
clover.
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