How did the whorled leaves of Calamites resemble those of living horsetails?

The extinct giant horsetails known as Calamites resembled living horsetails in their leaf arrangement because both plants feature leaves that emerge in spokelike whorls at regular intervals along their jointed stems.12

While the leaves of Calamites were arranged in these characteristic whorls at the nodes, the leaves of modern Equisetum species are generally more reduced, often forming a toothed sheath that clasps and encircles the stem at each node. Both groups share the fundamental Equisetopsida architecture of jointed, ribbed stems with leaves and branches originating from these nodes.132