Have you every looked closely at tree leaves in spring? Our eyes are drawn to showy flowers and flitting birds, but a close look at emerging leaves shows some astonishing beauty. The most interesting thing about spring leaves is the intricate folding. Leaves are often folded in half (as in redbud and hickory) or have complicated, compact folding schemes (as in oak and ash). Watching leaves emerge from their tight folding in buds to become full-grown leaves is fascinating.
Next time you are outside, have a look at some growing leaves. Visit the same plants over a few days and you will be amazed at the rapid changes you see.
Here are a few pictures of spring leaves in development (I will add more later). Click on the pictures to see a high-resolution version.
bitternut hickory, Carya cordiformis. Leaflets are folded in half as the rachis (leaf stem) grows.
Yellow buckeye, Aesculus flava. Leaves emerge with the flowers. Leaflets are tightly rolled.
Eastern redbud, Cercis canadensis. Leaves are folded in half as they emerge, quickly unfolding.
northern red oak, Quercus rubra. Bright red leaves are compactly folded along sinuses. The leaves transition from red to green as they unfold.
Two pictures of green ash, Fraxinus pennsylvanica. Leaflets are folded in half and folded against the rachis, spreading and unfolding as they develop.
