Plant Systematics : Pteridophytes

Horsetail (Equisetum), a type of sphenopsid.
Horsetail (Equisetum), a type of sphenopsid.

The Pteridophytes are the most primitive vascular plants, having a simple reproductive system lacking flowers and seed. Pteridophytes evolved a system of xylem and phloem to transport fluids and thus achieved greater heights than was possible for their avascular ancestors. This greater height gave them an evolutionary advantage because they were better able to disperse spores, which give rise to new plants.

Pteridophytes are comprised of Ferns and their allies:

  • "Whisk Ferns" such as Psilotum
  • Lycopods such as Lycopodium, Selaginella, and Isoetes
  • Horsetails (Equisetum)

A tropical Treefern.
A tropical Treefern.

While the true ferns are the most easily recognizable of the Pteridophytes, Lycopodium and Equisetum also can be found growing wild in our area. Horsetails are occasionally cultivated, and grow in wet soil around ponds and streams.

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