On normal plants of my variety the quinquefoliolate leaves usually
compose the majority, when there are no weak lateral branches, or when
they are left out of consideration. Next [351] to these come the fours
and the sixes, while the trifoliolate and seven-bladed types are nearly
equal in number. But out of a lot of plants, grown from seed of the same
parent, it is often possible to choose some in which one extreme
prevails, and others with a preponderating number of leaves with the
other extreme number of leaflets. If seed from these extremes are saved
separately, one strain, that with numerous seven-bladed leaves will
remain true to the type, but the other will diverge more or less,
producing leaves with a varying number of subdivisions.
Very few generations of such opposite selection are required to reduce
the race to an utterly poor one. In three years I was able to nearly
obliterate the type of my variety. I chose the seedlings with an
undivided primary leaf, cultivated them and counted their offspring
separately after the sowing. I found some parents with only 2-3% of
seedlings with divided primary leaves. And by a repeated selection in
this retrograde direction I succeeded in getting a great number of
plants, which during the whole summer made only very few leaves with
more than three blades.
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