Morphology and anatomy of anomalous cladodes in Sciadopitys verticillata Siebold & Zucc. (Sciadopityaceae)

Abstract

The needles of Sciadopitys verticillata Siebold & Zucc. (Sciadopityaceae) are inserted in the axils of the reduced scaly leaves and are thus generally regarded as cladodes. The evolutionary pathway leading to these cladodes remained, however, dubious and conflicting interpretations are given. Intermediate morphological structures are known basically from one single paper (Carrière 1868), giving only line drawings of the morphology without any further anatomical details. Attempts to produce such intermediate cladodes in experiments failed, but amongst thousands of checked individuals by chance one was found displaying such intermediate or malformed cladodes. These were analyzed morphologically and anatomically in detail. The results gave new insights into the evolution of these cladodes and might raise new questions about the monophyletic origin of the gymnosperm leaf.