Epicuticular wax ultrastructure and classification of Ranunculiflorae
Epidermal surfaces of about 199 species from 66 genera of ranunculiflorous families are examined by scanning electron microscopy. The micromorphology of their epicuticular wax crystals is presented and discussed under taxonomic aspects. All families of th
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Epicuticular wax ultrastructure and classification of Ranunculijlorae WILHELM BARTHLOTT and INGE THEISEN Received November 11, 1994
Key words: Angiosperms, Ranunculiflorae. -Cuticle, wax, seanning electron microscopy, wax ultrastructure, systematics, taxonomy. Abstract: Epidermal surfaces of about 199 species from 66 genera of ranunculiflorous families are examined by seanning electron microscopy. The micromorphology of their epicuticular wax crystal s is presented and discussed under taxonomic aspects. All families of the Ranunculiflorae s. str. (Ranunculales, Papaverales) prove to be highly uniform: apart from a few exceptions they are characterized by the presence of clustered wax tubules (Berberis type), chemically dominated by the secondary aIcohol nonacosan-10-01 in the species analysed. This is in marked contrast to the M agnoliidae s. str. (Aristolochiales, Laurales s.l., Magnoliales), which are almost uniformly defined by transversely ridged crystals of the Aristolochia type, chemically characterized by the presence of palmitone and the absence of nonacosan-10-01. However, the Canellaceae, Nelurnbonaceae, and Winteraceae produce the Berberis type tubules similar to Ranunculiflorae. This suggests a reconsideration of the position of these families and in particular for N elurnbo a close relation to the Ranunculiflorae also based on other chemical data. Within the polyphyletic Harnarnelididae the "lower" families Cercidiphyllaceae, Daphniphyllaceae, and certain genera of Harnarnelidaceae are also characterized by Berberis type waxes.
Over the last decades systematically relevant information on structure and composition of the plant cutide based on SEM studies have been published (reviews in BEHNKE & BARTHLOTT 1983, JEFFREE 1986, BARTHLOTT 1990). The cutides of the majority of higher plants are covered with epicuticular wax secretions. Epicuticular "waxes" occur throughout bryophytes, pteridophytes, gymno- and angiosperms. They are chemically diverse mixtures oflipophilic substances like long-chain fatty acid s (true waxes), alkanes, ketones, esters, and cydic compounds like pentacydic triterpenes, phytosterols, and fiavonoids. These substances occur usually as local projeetions of crystalline nature (JEFFREE & al. 1975) exhibiting surprisingly a high ultrastructural diversity. The micromorphology of epicuticular wax crystals revealed by SEM has provided valuable new criteria for the dassification of angiosperms (BARTHLOTT 1993, DITSCH & BARTHLOTT 1994, FRÖLICH & BARTHLOTT 1988, HENNIG & al. 1994, THEISEN & BARTHLOTT 1994). U. Jensen et al. (eds.), Systematics and Evolution of the Ranunculiflorae © Springer-Verlag Wien 1995
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The monocots are characterized by the presence of two wax types: paralleI oriented platelets (Convallaria type) within most hhiflorous families ineluding Triuridales. The subelasses Commelinidae, Zingiberidae, and Arecidae are characterized by aggregated rodIets with longitudinal striations (Strelitzia type). The core group of Magnoliidae (Aristolochia
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