Equisetaceae, sometimes called the horsetail family, is the only surviving family of Equisetales, a group with many fossils of large tree-like plants that possessed ribbed stems similar to modern horsetails. All living horsetails are placed in the genus Equisetum. Leaves are greatly reduced, arranged in whorls fused into nodal sheaths. Stems are jointed and ridged. Horsetails reproduce by spores borne in cone-like structures at the tips of some of the stems.