Equisetaceae: Horsetail Family
Although they do not bear much resemblance to other ferns, horsetails and scouring rushes are in fact true ferns. This is because of of the way they reproduce, rather than their appearance. Their family is one of the oldest plant families, and the forebears of these modest plants reached heights of 30 m, dominating the Paleozoic forests some 540–250 million years ago. The stems of horsetails and scouring-rushes are essentially identical, except that horsetails have many branches in whorls at regular intervals up the stem.