AP BIOLOGY

Detailed explanation-1: -Equisetopsida-Horsetails. The Equisetopsida [Equisetales], commonly called the equisetophytes, sphenophytes, or sphenopsids, are a monophyletic group that diverged early in the evolution of vascular plants.

Detailed explanation-2: -horsetail, (genus Equisetum), also called scouring rush, fifteen species of rushlike conspicuously jointed perennial herbs, the only living genus of plants in the order Equisetales and the class Equisetopsida.

Detailed explanation-3: -Horsetail has several distinguishing characteristics. One such characteristic is horsetail’s hollow stems (Figures 1 and 3). Its stems also are jointed, can easily be separated into sections, and have siliceous ridges that make it rough to the touch.

Detailed explanation-4: -Ferns, club mosses, horsetails, and whisk ferns are seedless vascular plants that reproduce with spores and are found in moist environments.

Detailed explanation-5: -Horsetails are very primitive plants belonging to the genus Equisetum, vascular plants that reproduce by spores in a similar fashion to ferns. The plant consists of long, hollow, narrow stem segments with minisule, non-photosynthetic leaves.