Progymnospermophyta
Quick Summary
The extinct division Progymnospermophyta is considered ancestral to seed plants. The most well-known progymnosperm is Archaeopteris, a Devonian plant that was once thought to be a fern. It possessed wood similar to conifers and was likely heterosporous, meaning it produced two types of spores. Archaeopteris exhibited characteristics anticipated in a seed-plant ancestor and is believed to have given rise to multiple gymnosperm groups. The earliest recognized seed plants were the extinct pteridosperms, or seed ferns, which emerged in the Devonian Period and were common by the Carboniferous Period.12
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