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Vegetative Growth of Decodon allenbyensis (Lythraceae) from the Middle Eocene Princeton Chert with Anatomical Comparisons to Decodon verticillatus.
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Large numbers of roots and stems of aquatic Lythraceae have been found in association with fruits and seeds of Decodon allenbyensis Cevallos-Ferriz et Stockey in the Princeton chert, British Columbia, Canada. The permineralized fossils come from layer 43 in the chert, part of the Middle Eocene, Allenby Formation. Vegetative remains were studied using the cellulose acetate peel technique in an attempt to reconstruct the whole plant of D. allenbyensis. Reconstruction is based on close anatomical comparisons of tissues in the fossil organs to those of extant Decodon verticillatus (L.) Ell. and on attachment of organs and tissue systems. A detailed description of both root and stem wood anatomy is provided for the fossil species. Stem anatomy is revised for extant D. verticillatus, and detailed root anatomy is described for the first time using paraffin sectioning techniques and scanning electron microscopy. Fossil roots and stems show diffuse porous wood with vessels that are solitary or in radial multiples of two to five with numerous tyloses. Heterocellular rays vary from one to at least five cells wide. Secondary phloem with clusters of thick-walled fibers is preserved in some axes. Most roots and some stems show distinctive concentric layers of thin-walled lacunate phellem, characteristic of submerged aquatics. This tissue has been described in extant Decodon J.F. Gmelin and other Lythraceae. Anatomy of D. allenbyensis indicates that these plants were growing under submerged conditions with stable water levels at the edge of a quiet body of fresh water.
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- Date created
- 2003
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- Article (Published)
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- Copyright 2003 by The University of Chicago