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Williamsoniaceae

Summary

Williamsoniaceae is a family within the Bennettitales, an extinct group of seed plants within the Cycadophyta subdivision. Members of this family are believed to have been around two meters tall and with widely serrate leaves along a central stem. Reproductive organs of the Williamsoniaceae have varied widely in the fossil record but almost all have been found to be borne on stalks emerging from a ring of leaves.[1]

Williamsoniaceae
Temporal range: Triassic–Cretaceous
Restoration of Wielandiella
Diagram of Weltrichia, a male reproductive structure
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Order: †Bennettitales
Family: †Williamsoniaceae
(Carruthers) Nathorst, 1913
Genera
  • Zamites (leaf, in partim)
  • Anomozamites (leaf)
  • Ischnophyton
  • Kimuriella (whole plant)
  • Pterophyllum (leaf)
  • Otozamites (leaf)
  • Wielandella (whole plant)
  • Williamsonia (female reproductive structure)
  • Williamsoniella (bisexual reproductive structure)
  • Weltrichia (male reproductive structure)
  • Bucklandia (axes)
  • Bennettistemon (male pollen organ)
  • Vardekloeftia (female seed cone)
Pterophyllum fossil from Shamshak Formation, Middle Jurassic, Iran

Reproduction edit

This family is different from Cycadeoidaceae by having the presence of cones leaving the major axis and lateral branches associated with a long peduncle covered by bracts. Some of this family reproduce by sporangia and others only produce ovule or pollen sacs.[2]

References edit

  1. ^ Meyen, Sergei V. (1984). "Basic Features of Gymnosperm Systematics and Phylogeny as Evidenced by the Fossil Record". Botanical Review. 50 (1): 1–111. doi:10.1007/BF02874305. JSTOR 4354028. S2CID 38485693.
  2. ^ Paleontologia Paleovertebrados e Paleobotânica Autor : Ismar de Souza Carvalho. Editora Interciência. Archived 2016-03-04 at the Wayback Machine