A hypothetical account for the emergence of a sporophyte generation during the evolution of vascular plants. It postulates that early plants were exclusively haploid gametophytes. At some point a zygote ‘germinated’ mitotically instead of meiotically, producing a rudimentary diploid sporophyte. Hence, a sporophyte generation was ‘inserted’, or interpolated, into the life cycle. The sporophyte evolved to become increasingly elaborate and the more prominent form – as in modern seed plants – while the gametophyte became progressively reduced. Compare transformation hypothesis.
Subjects: Biological Sciences.