The growth habit of Lepidodendron serratum Felix

Abstract

The question as to whether all of the species of the paleozoic genus, Lepidodendrom, were arborescent with secondary growth or whether some of them may have been of vine or semi-herbaceous habit with only primary tissues, has been investigated by observation of over 200 specimens of Lepidodendron serratum Felix. None of the over 200 specimens (many of which reached an apparent maximum diameter of 10 cm) exhibited any form of secondary growth either vascular or periderm. In addition, one specimen showed a distinctive asymmetrical form, with the stele occupying a marginal position and all of the leaf traces leading to leaf bases localized on the side of the stem opposite the stele. This type of anatomy is directly comparable to that found in the stems of many living lianas and along with the strong evidence for lack of secondary growth seems to indicate that L. serratum was a "lax, flexuose" plant as originally postulated by Felix.