I think its called <span>metamorphism.</span>
The f1 generation may have genes for short plants just that the genes for long plants are dominant over the genes for short plants(recessive) so when cross pollination happen and that two f1 long plants which are homozygous cross pollinate, the recessive genes have a chance of being paired up in new offspring(F2 offspring) thus the possiblity of short plants in f2 generation
