Although
achenes obtained
from interspecific hybridization
germinated,
they did not develop well and died at the hypocotyl phase,
which is the post-zygotic barrier to hybridization. Marta et al.
(2004) reported that post-zygotic barriers were observed in diploid
and octoploid crosses and their reciprocals, and the achenes from
interspecific hybridization of diploid and octoploid species showed
that the development of embryos and endosperm was poor, as
some serial microtome sections did not show these tissues. Similarly,
achenes from interspecific hybridization of octoploid and
diploid species grew abnormally, not only in terms of pollen grain
germination and tube growth, but in embryo and endosperm development
as well.