04 Fakultät Energie-, Verfahrens- und Biotechnik
Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/5
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Item Open Access Konstruktion, Leichtbau und Ökonomie bei Pflanzen(1989) Kull, Ulrich; Herbig, AstridDie Festigkeitseigenschaften von Achsen aus Pflanzenarten unterschiedlicher Stellung werden mit Hilfe der BIO-Methode (nach F. Otto) beschrieben und zu Energiegrößen in Beziehung gesetzt. Damit lassen sich Aufwandswerte K (dirnensionslos) berechnen, die dann auf die Lebensdauer der Achsen bezogen werden. Konstruktiv gute Wirtschaftlichkeit zeigen Achsen vom Bautypus der Gräser, Blattstiele von Farnen und Achsen vom Hopfen (Liane). Der K-Wert ausdauernder Achsen liegt höher, K/Lebensdauer ist aber ähnlich wie bei einjährigen. Kurzlebige Blüten- und Fruchtstiele haben einen hohen Aufwand je Zeit. Die Größe K/Lebensdauer wird in Verbindung mit der Selektion gebracht. Vergleiche mit menschlichen Konstruktionen schließen sich an.Item Open Access Leaves and ramification(1992) Herbig, Astrid; Kull, UlrichLeaf veins have two main functions: they constitute the mechanical reinforcement system and the transport system. To analyse the vein pattern it is necessary to have a - as far as possible - quantitative description of the vein system of real leaves. Quantities used in modern plant anatomy have to be completed by measurements of the fractality of the ramification system (as grid dimension and as exponent of scaling) and by a measure for the partition of the leaf area and the complexity of the patch pattern which we call the supply coefficient. The leaf venation pattern is a result of the evolutionary process. To find out criteria of a relative optimization during this process, we used simple models of the ramification of leaves. By computer methods such models were tested regarding their quality as a reinforcement system. In real leaves. there must be compromises between reinforcement and transport functions. The quantities used to describe the leaf vein systems can be applied to other reticulate sytems. We selected street nets of towns , and some comparisons between the ramification systems of leaves and of towns show similarities and differences which are discussed.Item Open Access Leaf venation patterns and principles of evolution(1994) Kull, Ulrich; Herbig, AstridLeaf venation patterns (of dicots and for comparison of ferns) are analyzed according to form and function. From topological investigations of the gross vein system and the patterns of small veins forming areolae (vertices and adjacents, geometry of gross veins, scaling exponents) and from results of physiological anatomy and ecophysiology we deduce a major contribution of selforganization processes in the development of the angiosperm leaf vein system. The resulting plasiticity of the construction of small veins, allowing function under a variety of circumstances, is a prerequisite for the adaptation of angiosperms to very different environmental conditions. In the ontogenetic selforganization process of the small veins the phloem initiation probably acts as a pace-maker. Methods of morphodynamics and functional morphology are used to discuss, when, why and how this key invention for the angiosperm leaf arose during the evolutionary process.