Computer simulation of sphenopsid architecture. Part II. Calamites multiramis Weiss, as an example of Late Paleozoic...

A late Carboniferous arborescent sphenopsid has been modelled for the first time with the AMAP 1 system. The natural entity consisting of the three form species 'Calamites multiramis/Annularia stellata/Calamostachys tuberculata' (respectively the trunk/branches and foliage/cones) representing the aerial part of this plant is reconstructed and its architecture modelled. The different growth stages are extrapolated, generating a dynamic view that did not exist until now. The model is based on the hypothesis that the modelled part is not preformed but results from the successive production and elongation of internodes. This growth led to old ontogenetic stages of the plant in agreement with Remy and Remy's reconstruction (Remy, W., Remy, R., 1977. Die Floren des Erdaltertums. Verlag Glückauf, Essen, 468 pp.). With its verticillate sterile organs and cone-shaped fructifications similar to the extant herbaceous relative Equisetum, this calamite is distinguished from the latter taxon by having possible 'throw-away' phyllomorphic branches. We assumed the presence of a restricted zone of branches located in the apical part of the trunk. Moreover, the production of reproductive organs that succeeds the vegetative stage implies a major photosynthetic phase associated with a monocarpical form of development of the fossil plant.