New perspective on the architecture of the Late Devonian arborescent lycopsid Leptophloeum rhombicum (Leptopiiloeaceae)

A reinvestigation of the previously described Leptophloeum rhombicum trunk front the Late Devonian (Frasnian) Huanchiateng, Formation or Hubei. China provides a new perspective on the architecture of this arborescent lycopsid. It is preserved as a flattened. silicified petrification with an unevenly permineralized primary vasculature and spirally arranged rhombic leaf cushions. which agree with the diagnosis of L. rhombicum Dawson distributed worldwide in the Late Devonian. Taxonomically. this plant Should be to its own family and within the order Isoetales sensu lato. The anatomy. from different levels of the trunk. demonstrates that the ontogeny of the plant may conform to a determinate growth pattern. Combining previous data with current architectural analysis it suggested that the L. Mombicum tree had a pseudomonopodial branching pattern rather than an iso-dichotomous branching crown IN previously proposed. New reconstruction of the general habit for this tree is given and consists of three major architectural units: a stigmarian rhizomorph, a main trunk. and lateral branches. When these results are. considered with recent cladistic work-. L rhombicum may have developed similar growth architecture to some Farnennian and Carboniferous arborescent Lycopsids. This growth represents one of the archetypal architectures found in the Isotates s.l. extending from the early Late Devonian.