Vegetative Growth of Eorhiza arnoldii Robison and Person from the Middle Eocene Princeton Chert Locality of British Columbia.

• Author(s) / Creator(s)

  • Pigg, K.B.
  • Stockey, R.A.

• Anatomical studies of several thousand specimens of Eorhiza arnoldii Robison and Person rhizomes and their attached organs have added significantly to our knowledge of these Middle Eocene, semiaquatic dicotyledonous plants from the Princeton chert. Anatomical structure of Eorhiza was studied through selial sections on cellulose acetate peels. In order to establish the growth habit for these plants, individual axes were mapped as to their three-dimensional positions in the chert matrix. Plants grew from an extensive sympodial rhizome system similar to many living monocots and exhibited subopposite branching. Branch- es gave rise to rhizome sympodia or to branches bearing small scale-leaves. The architecture of Eorhiza conforms to the Tomlinson Model proposed by Halle, Oldeman, and Tomlinson. Leaves are ensiform, equitant, unifacial (isobilateral), and monocot-like with a large central lacuna. Rhizomes show typical dicot stelar anatomy. The presence of an aerenchymatous cortex and the plants' association with freshwater animal remains and representatives of known aquatic plant families, such as Nymphaeaceae, support an aquatic habitat for Eorhiza. The presence of rhizomes that produce roots bearing secondary and tertiary roots indicates in situ preservation of extensive rhizome systems at least 41 cm in length. A reconstruction of the vegetative body of Eorhiza is presented and a hypothesis offered concerning the attachment of reproductive structures to these plants.

• Date created

  1994

• Subjects / Keywords

  • Acorus
  • RBCL
  • Permineralized fruits
  • Allenby Formation
  • Seeds
  • Monocotyledons
  • Plants
  • Araceae

• Type of Item

  Article (Published)

• DOI

  https://doi.org/10.7939/R39K45W2Q

• License

  Copyright 1994 by The University of Chicago