A delightful but sparsely observed phenomenon is the budding of trees in spring, a process that, contrary to widely held belief, does not involve formation of buds.
When the tree was in its growth phase the previous summer, the buds developed and have been dormant on the tree since the slowing down of growth in the fall. In spring, the longer periods of sunlight stimulate the resumption of growth of the bud, followed by the unfurling of leaves and flowers.
The first sign of budding is the expansion or parting of the protective scales that cover the bud as the underlying tissue begins to grow. Each species has a particular number of scales. Willow has a single scale that gradually slides toward the end of the bud, revealing the green tissue beneath. Basswood has a pair of dark red scales, one larger than the other, which separate at the tip and show a tan substance in between. Striped maple also has two reddish scales, of the same size, and uncovers white material as they part. Sugar maples, beeches, birches, hornbeams, and oaks have multiple imbricate scales which overlap like shingles. The first sign of budding in their case is a band of pale brown above the edge of each dark brown bud scale, the bands increasing in size as the bud lengthens longitudinally. As the bud grows, the scales fall off.
Many trees flower before leafing, while others do it the other way around, but all of them flower. We seldom notice those that are greenish and not shaped like your typical flower, but seeds cannot be produced without pollen and ovaries, and most trees get started in spring. The shadbush (also known as juneberry or serviceberry) flowers early. Clumps covered with silky white hairs emerge from between the scales. The hairs insulate the new tissue against the cold. Before any trees have leafed, the floppy shadbush blossoms will be adorning the woods with occasional flashes of white.
Red maples and silver maples are also early bloomers. Both have red buds that grow fat and then explode into jazzy red and yellow fluff. The elms poke shaggy little green flowers out of their buds quite early, but you probably won't notice them until there's a rainstorm, when many elm flowers blow down and litter the ground.
Wild cherry is among the trees that leaf before flowering. Dissecting a bud can be fascinating, especially with a magnifying glass to discern the embryonic leaves, which have the same shape as the mature leaves, but in miniature. There are generally a number of leaves contained within each bud, sometimes with flowers and sometimes without. Sassafras, which has three different leaf shapes on each tree, is interesting because inspection reveals that the outer leaves in each bud are oval, the second layer of leaves is mitten-shaped, and the inner layer has three lobes.
For more on buds, see the blog entry Watching Trees Bud.
