The genus has been described as having an unusual—and unusually complex—
morphology, superficially
palm-like. Specimens are between As the xylem bundles grew in diameter, they would split apart from one another near the apex of the trunk, thus limiting the overall height. The trunk apex was domed rather than tapered, and like the trunk base, wider than the midsection. Some trunks may have forked. As the trunk grew, the lower branches would be shed; a mature tree might in the course of its growth shed as many as 700 to 800 branches, creating a thick carpet of decaying twigs on the ground below, with few
understory plants observed. Where other cladoxylopsids shed their branches smoothly,
Calamophyton left small stubs behind on the trunk. The
root system consisted of several hundred to more than a thousand strap-like roots of in diameter and, for the larger trunks, in excess of in length. The roots were approximately straight, undivided, and extended almost directly downward into the soil. The fossil record indicates that in spite of their small diameter, they were stiff and hardy.
Calamophyton reproduced not by seeds, but via
spores, one of several characteristics suggesting a relationship with the
Pteridophyta. == Earliest-known forest ==