Producing two different kinds of spores.
- ‘Therefore, improved sampling and a better understanding of the morphology of fossils with affinities to these families are necessary to understand the origin and evolution of the heterosporous fern clade.’
- ‘Isoetes helps discriminate between these explanations as it lacks vessels and has a large genome despite being heterosporous, suggesting that vascular evolution is the key factor.’
- ‘Many paleobotanists believe that the earliest seed plants evolved from heterosporous Middle Devonian plants like the progymnosperms.’
- ‘Both of these genera are heterosporous, meaning that each species produces two distinctly different types of spores: microspores and megaspores.’
- ‘Some of the large sphenophyte trees of the Paleozoic were heterosporous, producing large megaspores and small microspores, and probably retaining the megaspore in the strobilus.’