New diversity among the Trochodendraceae from the Early/Middle Eocene Okanogan Highlands of British Columbia, Canada, and northeastern Washington State, United States

Kathleen B. Pigg, Richard M. Dillhoff, Melanie L. DeVore, Wesley C. Wehr

Research output: Contribution to journalArticle

27 Scopus citations

Abstract

Newly recognized fossil infructescences and leaves of the Trochodendraceae are described from the Early/ Middle Eocene McAbee and One Mile Creek sites of British Columbia, Canada, and Republic, eastern Washington State, United States. Trochodendron drachukii Pigg, Dillhoff, DeVore, & Wehr sp. nov., from McAbee, is an infructescence similar to that of extant Trochodendron aralioides Sieb. & Zucc. but strongly paniculate rather than racemose. This new species is larger and more robust than those of the Eocene flora of Republic, Washington, and has attached fruits quite similar to both extant Trochodendron Sieb. & Zucc. and Miocene fossils from Asia and western North America. Associated leaves are similar to those of extant Trochodendron except for sometimes bearing short basal auriculate extensions of the lamina. They differ from Trochodendron nastae Pigg, Wehr, & Ickert-Bond leaves from Republic that have palmate rather than pinnate venation. Tetracentron hopkinsii Pigg, Dillhoff, DeVore, & Wehr sp. nov. from One Mile Creek and Tetracentron sp. from Republic have leaves remarkably like those of extant Tetracentron Oliver, firmly establishing the presence of this genus in the Eocene. This study demonstrates that within the Trochodendraceae, a poorly understood group within the eudicot grade, both extinct forms as well as plants with quite modern-appearing fruits and leaves were present by the Eocene in northwestern North America.

Original languageEnglish (US)
Pages (from-to)521-532
Number of pages12
JournalInternational Journal of Plant Sciences
Volume168
Issue number4
DOIs
StatePublished - May 1 2007

Keywords

  • Eocene
  • Okanogan Highlands
  • Tetracentron
  • Trochodendraceae
  • Trochodendrales
  • Trochodendron

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Plant Science

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