Leaf shapes and venation patterns

• Author(s): Reis, A. Heitor
• Date: 2012
• Persistent ID: http://hdl.handle.net/10174/7620
• Origin: Repositório Científico da Universidade de Évora
• Subject(s): leaf shapes; venation patterns; water ascent; Constructal Law
• Document Type: Part of book or chapter of book
• Language: English
• Editor(s): Rocha, L. A. O.; Lorente, Sylvie; Bejan, Adrian

Description

We present an analysis of leaf shapes and venation patterns based on a new assumption of the way how water flows in plants, together with the assumption that leaf shapes and leaf venation patterns have evolved in time such as to provide easier and easier access to its internal currents (Constructal Law). Then, by minimizing the global resistance to flow we anticipate the number of veins in relation to leaf shape (slenderness and vein insertion angle) and prevalent environmental conditions (represented by the potential for leaf water intake from the atmosphere). We also anticipate that leaves in dry climates will be slender and shorter, and with more veins as compared with those of plants adapted to wet environments. We finish by showing some cases in which the theory describes the characteristic of real leaves closely.