Sphenophyllales

The Sphenophyllales were an order of extinct plants that existed from the end of the Devonian Period to the beginning of the Triassic Period, approximately 360 to 251 million years ago. This order is coextensive with the genus Sphenophyllum.12

Sphenophyllum plants are often reconstructed as shrubs or creeping vines. They featured a distinct node-internode structure, with branches and leaves arranged in whorls at each node. The leaves were triangular, and the plants produced spore-bearing cones similar to those of modern horsetails. Unlike horsetails, Sphenophyllum lacked a hollow central stem, as its water-conducting cells were arranged in a central triangle. These plants typically grew in floodplain swamps.1