Hernandez-Castillo, Genaro , Stockey, Ruth A. , Rothwell, Gar W. .
Mesarch solenostelic ferns from the early Cretaceous Apple Bay locality, British Columbia, Canada.
Three types of solenostelic rhizomes have been identified in the early Cretaceous Apple Bay flora from Vancouver Island, British Columbia.Rhizomes are found in calcareous concretions that were studied using the cellulose acetate peel technique.One rhizome, 2-3 mm in diameter, has a parenchymatous pith with scattered sclerenchyma, and a cortex divided into three zones.The amphiphloic solenostele has inner and outer endodermis, pericycle, phloem and xylem and a single C-shaped, Gleichenia-type leaf trace. The outer endodermis is continuous with the endodermis of the leaf trace.Xylem maturation is mesarch, and the metaxylem is one to five cells thick.The inner cortex is sclerotic and the outer cortex varies from thick-walled parenchyma to sclerenchyma externally.These rhizomes resemble those of extant Anemia (Schizaeaceae).The second rhizome is larger, 4 mm X 8 mm in diameter, metaxylem 1-3 cellsthick, with a parenchymatous pith and cortex.Cells with dark contents and secretory structures occur in the cortex.This stem, that is associated with a dennstaedtioid stipe trace, may be a sporeling, and is likely a member of the tree fern clade.The third type of rhizome, 10 mm X 6 mm in diameter, has a completely sclerotic pith and cortex, with a core of thicker-walled cells in the center of the pith.This rhizome is also solenostelic and produces a single leaf trace that arises asymmetrically and is also very sclerotic.Xylem is mesarch, with metaxylem that is 1-4 cells thickExternally this rhizome shows evidence of a ramentum. This rhizome is associated with fertile dipterid foliar remains.These remains contribute to the rapidly expanding knowledge of diversity of ferns in the early Cretaceous.
1 - Ohio University, Department of Environmental and Plant Biology, Porter Hall, Richland Avenue, Athens, Ohio, 45701-2979, USA
2 - 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: 1:30 PM