A primitive plant that is a member of the plant division Sphenophyta of which only one genus (Equisetum) survives today. This is probably one of the oldest genus of vascular plants. Seedless with primitive leaves and ribbed stems that contain silica. The ribbed stems of the plant are jointed and can be separated at each node. Since the stems contained silica, this provided for a grit that was used to scour cooking utensils, sharpening and polishing. This plant was also consumed to a limited extent.

Horsetails are primarily organisms of the past, dating back to the Devonian Period (409-363 million yrs. ago). They thrived during the Carboniferous Period, from 363 to 290 million yrs. ago During this time the climate was favorable to these plants allowing them to become tree size. Now usually less rthan 4 feet tall. The horsetails of Carboniferous period make up vast deposits of today's coal. The living species have little economic significance.