Mindell, Randal , Stockey, Ruth A. , Rothwell, Gar W. , Beard, Graham .
Vegetative gleicheniaceous remains from the Eocene of North America.
Gleicheniaceae have an extensive fossil record dating back to the late Paleozoic. While species assigned to this fern family are known from Cretaceous North American floras, Tertiary records are not known from the New World. A permineralized rhizome and an attached stipe base with distinctive gleicheniaceous characters has been identified from the Appian Way locality (Eocene) on Vancouver Island, British Columbia, Canada. The specimens come from calcareous concretions and are studied using the cellulose acetate peel technique. The mixed protostelic rhizome is marginally mesarch with spirally thickened protoxylem elements and scalariform metaxylem tracheids that occur in clusters separated by small diameter parenchyma cells. Phloem and pericycle occur in a continuous band around the xylem but are not well preserved. Roots arise on all sides of the rhizome, with traces running obliquely through the cortex. The cortex can be divided into an inner layer of small sclerotized cells and an outer layer of relatively thin-walled, larger cells. The frond trace arises with a large patch of sclerenchyma between the trace and the protostele. Longitudinal sections through the trace show long metaxylem tracheids up to 1500 Ám long and up to 200 Ám wide with septa that may represent tyloses. Numerous associated but isolated frond segments have also been observed that show a pinched and inrolled C-shaped vascular trace that may also be gleicheniaceous. These traces have numerous protoxylem strands (six or more), and the ground tissues of these stipes can be either sclerotic or parenchymatous. Together, these remains suggest that Gleicheniaceae persisted on the western margin of the North American continent until at least the Eocene.
1 - Ohio University, Department of Environmental and Plant Biology, Porter Hall, Richland Avenue, Athens, Ohio, 45701-2979, USA
2 - Vancouver Island Paleontological Museum, 151 West Sunningdale, Qualicum Beach, British Columbia, V9K 1K7, Canada
3 - University of Alberta, Department of Biological Sciences, CW 405 Biological Sciences Building, Edmonton, Alberta, T6G 2E9, Canada
Presentation Type: Paper
Location: Maybird (Cliff Lodge)
Date: Wednesday, August 4th, 2004
Time: 1:45 PM