Lower and upper branches of Coast Redwood display very different leaf shapes, here shown against bark of a fallen tree. Large, wide sprays are typical of lower branches and small, scale-like leaves are typical of canopy branches. A gradient of intermediate leaf shapes occurs with increasing height above ground. Water transport has been shown to be the causal factor, causing leaf stress in high branches. (See Koch, Sillett, et al., Nature 428:851-854, 22 Apr. 2004.)
© Gregory G. and Mary Beth Dimijian