Why Do Most Angiosperms Have Alternate Phyllotaxy, with Leaf Emergence

Multiple Choice

Why do most angiosperms have alternate phyllotaxy, with leaf emergence at an angle of 137.5° compared to leaves above and below?

A) to allow maximum exposure to light
B) to promote a leaf area index above 8
C) to reduce shading of lower leaves
D) to allow maximum exposure to light and to reduce shading of lower leaves