Upchurch, Garland , Vikulin, S.V. .
Improved Techniques for the Preparation of Leaves From Extant and Organically Preserved Fossil Seed Plants.
Anatomical details of the leaf cuticle have played an important role in paleobotanical research for over a century. Yet preparation methods have diverged relatively little from the protocol proposed by Schulze in the mid-1800s, in which carbonized leaf material is treated with nitric acid and potassium chlorate, followed by a dilute base, typically KOH or NaOH. In this talk we describe alternative methods for the maceration of leaf cuticles from extant and fossil seed plants and for the clearing of organically preserved fossil leaves to reveal venation. For leaves of extant seed plants, we propose a two-step method of cuticle maceration that overcomes problems inherent with Schulze’s method and later techniques published by Stace and others. For the leaves of organically preserved fossils, we propose five methods, with the optimum method depending on: 1) whether partial clearing or total maceration is desired, 2) the extent to which the original organic material has been altered by thermal maturation and chemical changes, and 3) whether or not lignified structures are to be studied. For material with little thermal maturation, chloral hydrate can be used either by itself or in combination hydrogen peroxide and other chemicals to clear whole leaves for morphology and to macerate their cuticles for light microscopy and SEM. For thermally altered material, modifications of the Schulze’s method provide quality macerations of cuticle and can be used to clear leaves for venation. Side by side comparison of our methods with other methods, such as Schulze’s method and household bleach, indicates that our alternative methods can significantly decrease fragmentation of the cuticle and increase the recovery of epiphyllous fungi and resin bodies. Our methods also facilitate the sorting of lignitic plant debris and the observation of significant structures because they can render leaves transparent without making them fragile.
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1 - Texas State University, Department of Biology, 601 University Drive, San Marcos, Texas, 78666, USA
2 - V.L. Komarov Botanical Institute, Laboratory of Paleobotany, Russian Academy of Sciences, 2 Prof. Popov St., St. Petersburg, 197376, Russia
Presentation Type: Oral Paper:Papers for Sections
Location: Williford A/Hilton
Date: Wednesday, July 11th, 2007
Time: 11:15 AM