Evergreen Growth Logic

People often think of evergreen trees and shrubs as static, but they too go through seasonal transformations. An American Holly demonstrates this well. The photo shows three years worth of leaves. This spring's new leaves are olive green, last year's leaves are bright green, and the two year old leaves (yellow) are in the process of being cast overboard. The tree might look unhealthy, but the shedding of two-year-old leaves is as natural as when deciduous trees drop their one-year-old leaves in the fall.