Only one or two exceptions could be quoted, as
for instance the _Oenothera brevistylis_, which in its crosses always
behaves as a pure retrogressive variety. Instead of giving an exhaustive
survey of hybrids, I simply cite my crosses between _lamarckiana_ and
_biennis_, as having nearly the aspect of the last named species, and
remaining true to this in the second generation without any sign of
reversion or of splitting. I have crossed another elementary species,
the _Oenothera hirtella_ with some of my new and with some older Linnean
species, and got several constant hybrid races. Among these the
offspring of a cross between _muricata_ and _hirtella_ is still in
cultivation. The cross was made in the summer of 1897 and last year
(1903) I grew the fourth generation of the hybrids. These had the
characters of the _muricata_ in their narrow leaves, but the elongated
spikes and relatively large flowers of the _hirtella_ parent, and
remained true to this type, showing only slight fluctuations and never
reverting or segregating [264] the mixed characters. Both parents bear
large capsules with an abundance of seed, but in the hybrids the
capsules remain narrow and weak, ripening not more than one-tenth the
usual quantity of seed. Both parents are easily cultivated in annual
generations and the same holds good for the hybrid.
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