After the explosion of the cherry blossoms, magnolias, serviceberries, catalpas, and other showy flowers, summer often feels like an aesthetic drought because most of the trees are done blooming. But there is a subtle beauty that will never leave you once you notice it. Young leaves coming through in mid to late spring, throughout the summer, with second flushes, and the fully formed leaves are a wonder to behold. Green is a deceptive color, as it often blends with its surroundings, but the shapes of leaves are just as diverse as flowers in their creativity.
Early emerging leaves, and leaves that come to trees as they go through multiple flushes of leaves (like black cherry (Prunus serotina), for example, whose early leaves are often defoliated by tent caterpillars) are little works of art. Oak leaves in large masses are impressive on the tree, but every large oak leaf starts out as an intense concentrated red (see the young white oak (Quercus alba) leaves on the right). These leaves have significant amounts of anthocyanins, natural chemicals that act as sunscreen, giving it the color. These colors dominate before the green chlorophyll, the pigments that help in converting sunlight into food, takes over.
Other leaves are fascinating for how they unfold. The cat-face-shaped Tuliptree (Liriodendron tulipifera, on the left) leaves are folded up in a tiny package, released with the early flowers, and unfolding over several weeks in spring, before starting to develop. This efficiency in packaging is unrivaled in even the most efficient engineered electronics packaging, and surpasses it in elegance.
Nature keeps it weird
Even after the young leaves unfold acrobatically, they remain their mysterious shapes and continue to astound us in their diversity. One of my favorites remains the versatile Sassafras (Sassafras albidum). A tree historically used to create flavors in root beer, as well as medicinal applications, the leaves have a variety of mitten and heart shapes. The picture on the right shows some of the red the leaves also hold onto throughout the season, and the more regular shape they hold.
One of the most recognizable leaf shapes is the non-native Ginkgo (Ginkgo biloba, on the left). This leaf shape often shows up in fashion patterns, jewelry designs, and more. While the tree is considered to be a living fossil (with no real wildlife value or typical ecological niche), it’s a great ornamental tree that is urban hardy, with fascinating leaf shapes, and an amazing fall color display. This tree is a conifer although it looks like a broadleaf tree. The conifer aspect is best displayed when it drops all of its leaves at the same time in the fall (common with deciduous conifers). Although it’s spindly branch shape, and elegant fan-shaped leaves remain throughout the year.
More on leaves.
This just highlights a handful of trees of the hundreds of trees native and planted in our area. Here are some great resources for exploring our tree diversity:
I’ve got my leaf, let’s go! – An online guide to find out what species of tree your leaf goes to
Leafsnap – A great local resource and free app for identifying leaves. The app does not always work, but the reference guide is impeccable.
Why leaves change color – learn about the colors hidden underneath the green.
Trees up close – A great book on appreciating the complexity of leaves and seeds