Link to discussion of the reason for this. It contains 121,024 base pairs encoding 128 genes. The short lines indicate a few of the tRNA genes, some of which are labeled. But in all other vascular plants , this region is inverted and the order of the genes is precisely reversed. This provides further evidence that the other vascular plants we shall examine below, the sphenopsids ferns gymnosperms and angiosperms belong to a separate clade .
Horsetails often grow in sandy places and incorporate silica in their stems.
However, many other, much larger, species were dominant features of the Carboniferous and, like the early lycopsids, contributed to the formation of coal. Approximately 9500 species of ferns live on earth today. The ferns of temperate regions are smaller. They are usually found in damp, shady locations. Their leaves, called fronds , grow up from the rhizome each spring.