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Paleozoic Seed Ferns: Heterangium kentuckyensis sp. nov., from the Upper Carboniferous of North America.

  • Author(s) / Creator(s)
  • Heterangium kentuckeyensis sp. nov. is described from Lower/Middle Pennsylvanian sediments of eastern Kentucky, based on permineralized stems, petioles, frond members, laminar foliage, and roots, including several organs in attachment. Stems 2.2 to 5.8 mm in diameter are known in several developmental stages. The considerable variability in stelar and cortical histology within this one species emphasizes the need to reassess variability within previously described taxa. Fronds of H. kentuckyensis are at least twice pinnate and bear primary pinnae alternately at approximately right angles. Laminar pinnules have dichotomous venation, are at least 2-lobed, and comparable to foliage of the Sphenopteris-type. Stomata possess 6-7 subsidiary cells with abaxial papillae. The characters used to distinguish the subgenera of Heterangium are evaluated and found to be unreliable. Moreover, suggested phylogenetic schemes both within Heterangium and between this taxon and other lyginopterid pteridosperms based on these features are inconsistent with stratigraphic data. Until reproductive features are known, the classification of Heterangium species is best based on characters of the vegetative sporophyte, including stelar organization (particularly protoxylem architecture), cortical histology, and frond morphology.

  • Date created
    1987
  • Subjects / Keywords
  • Type of Item
    Article (Published)
  • DOI
    https://doi.org/10.7939/R37S7HV7D
  • License
    This version of this article is open access and can be downloaded and shared. The original author(s) and source must be cited.
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  • Citation for previous publication
    • Pigg, K.B., Taylor, T.N., and Stockey, R.A. (1987). Paleozoic Seed Ferns: Heterangium kentuckyensis sp. nov., from the Upper Carboniferous of North America. American Journal of Botany , Vol. 74, No. 8, 1184-1204