Blattgröße

Blattgröße (German for "leaf size") refers to the dimensions or surface area of a plant leaf and, in other contexts, the size of a sheet in printing and papermaking. In botany the term is used to describe individual leaf area, length and width, and overall form; in industry it denotes standard sheet formats and dimensions.

In plant science, Blattgröße is measured as leaf area (commonly in cm² or mm²) using tools such as planimeters, flatbed scanners with image analysis software, or leaf area meters. Measurements can be linear (length, width) or two-dimensional (projected area) and are often reported for fully expanded leaves at a defined developmental stage. Standardized sampling protocols help compare material across species, populations and environments.

Leaf size influences and reflects ecological and physiological processes including light capture, transpiration, boundary-layer heat exchange and water use. Large leaves are common in shaded, humid habitats where light capture is prioritized; small leaves are frequent in arid, cold or windy environments where heat and water loss must be limited. Blattgröße is affected by genetics, ontogeny, nutrient and water availability, temperature and light.

Applications include taxonomy, functional ecology, paleobotany (leaf physiognomy as a climate proxy) and forestry. In printing and papermaking Blattgröße refers to sheet dimensions and links to standardized formats (for example international A-series sizes) used in production and layout.