Here's why it's a bit confusing:
* Ferns are seedless vascular plants that reproduce using spores.
* Seed plants are a separate group that evolved later and reproduce using seeds.
The plants we call seed ferns were transitional forms, bridging the gap between the ancient, spore-bearing plants and the modern, seed-bearing plants. They were not true ferns, but they possessed features that resembled ferns.
Some of the most well-known groups of extinct plants that are often referred to as "seed ferns" include:
* Pteridospermales: These are a large and diverse group with a wide range of forms. They were dominant in the Paleozoic and early Mesozoic Eras.
* Glossopteridales: These plants were particularly common in the Southern Hemisphere during the Permian period.
* Corystospermales: These are a relatively small group, but they are important because they show some of the earliest signs of the evolution of flowering plants.
Remember: "Seed ferns" is not a formal taxonomic name but rather a general term for extinct plants with fern-like leaves but seed reproduction.
