Trimerophytopsida
†Trimerophytales Trimerophytopsida (or Trimeropsida) is a class of early vascular plants from the Devonian, informally called trimerophytes.Different authors have treated the group at different taxonomic ranks using the names Trimerophyta, Trimerophytophyta, Trimerophytina, Trimerophytophytina and Trimerophytales.At first most of the early land plants other than the bryophytes (i.e. the polysporangiophytes) were placed in a single class Psilophyta, established in 1917 by Kidston and Lang.[1] As additional fossils were discovered and described, it became apparent that the Psilophyta were not a homogeneous group of plants.[2][3] The subdivision is based on the type genus Trimerophyton, which might be expected to produce 'Trimerophytophytina' as the name of the subdivision, but the International Code of Nomenclature for algae, fungi, and plants allows the 'phyton' part of a genus name optionally to be omitted before '-ophyta', '-ophytina' and '-opsida'.