The first vascular plants evolved long before dinosaurs appeared on the Earth. Although seedless, these plants flourished in the warm, moist climate, sometimes growing to heights of over a hundred feet. Today only a few ground plants remain, for the spore-producing vascular plant has been replaced by coniferous and deciduous seed plants. Still present today are the spike mosses, ferns, horsetails, club mosses, and quillworts, tiny reminders of the lush vegetation that once covered the earth.
Ferns (Phylum Pterophyta )
Ferns are a common plant today, often found growing on the shady forest floor, especially along small watercourses. They are the one type of seedless vascular plant that has actually developed a leaf-like structure, commonly referred to by botanists as a frond. The ferns reproduce from spore sacs that form on the underside of the frond and are considered to be the most advanced of the seedless vascular plants.
Horsetails (Phylum Sphenophyta)
Horsetails, also called Equiseteum, are short, narrow plants that somewhat resemble asparagus. They do, however, have a small head, which is scientifically referred to as a strobilus. It is here that you will find many small leaves growing together. These leaves provide the energy and food for the plant to grow to a maximum height of one or two feet.
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Club Mosses, Quillworts, and Spike Mosses ( Phylum Lycophyta)
Today, this phylum contains three plant families, the club mosses, quillworts, and spike mosses. Club mosses and quillworts grow close to the ground, possessing modified tiny leaf structures that form small heads, called a strobilus. The spike mosses are also small, low plants, but their leaves spread out in fan-like structures resembling lichens. All these plants reproduce by spores.
Whisk Ferns ( Phylum Psilotophyta)
Lacking a root system, whisk ferns may be the oldest of the seedless vascular plants. Resembling small green twigs, the whisk ferns prefer warm, moist climates, where they often live non-parasitically in the crotch of trees and along swampy ground.