Effects of leaf blade narrowness and petiole length on the light capture efficiency of a shoot

Effects of the length: width ratio of a leaf blade and petiole length on shoot light capture were studied with computer simulation. Both a larger length: width ratio and longer petiole contributed to larger light capture per unit leaf area due to a reduced aggregation of leaf area around the stem. Other conditions being equal, shoots with narrow leaves and no petioles and those with wide leaves with petioles showed similar light capture as long as the mean distance of the leaf blade from the stem was the same. In shoots with a short internode and/or distichous phyllotaxis, however, narrow leaves contributed more to avoiding mutual shading than wide leaves with petioles. The predominance of light coming from a higher angular altitude also favored narrow leaves. The possible consequences of these results in the adaptive geometry of plant architecture are discussed.