Calamites
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Calamites is a genus of extinct arborescent horsetails to which the modern horsetails are closely related. Unlike their herbaceous modern cousins, these plants were medium-sized trees, growing to heig
Calamites stems
The foliage (Annularia) of Calamites
A diagram of a pith cast of Calamites
Calamites sp., Estonian Museum of Natural History
Archaeopteris
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Archaeopteris is an extinct genus of progymnosperm tree with fern-like leaves. A useful index fossil, this tree is found in strata dating from the Upper Devonian to Lower Carboniferous, the oldest fos
Calamites
…extinct in the early Permian, a time which also saw the origin and diversification of the herbaceous genus Equisetum, the only living sphenophyte genus. Archaeopteris How large are the giant horsetails…
Archaeopteris hibernica 2
A reconstruction of Archaeopteris macilenta from the Late Devonian, Walton Formation of Hancock, New York
A polished round of permineralised wood of Callixylon whiteanum from the Late Devonian Woodford Shale of Ada, Oklahoma
A. halliana