Biology / Unit 10 Bio 2181 short lesson, about 20 seconds
Homospory versus Heterospory
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The idea
A homosporous plant produces one spore type growing into a bisexual gametophyte; a heterosporous plant produces separate microspores and megaspores forming male and female gametophytes.
In practice
Most ferns are homosporous; some lycophytes are heterosporous, foreshadowing the pollen-and-ovule split seed plants later evolved.
Where people slip
Heterospory evolved independently in more than one lineage — it does not show those lineages share one ancestor.
Your place on the trail
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