Oat Plant Leaf Stages

Bud Development

• The first stage of leaf development is the formation of the bud. Buds begin to form at the base of the leaf petiole, or stem, during the summer months. The buds are surrounded by tough scales to protect the developing leaves inside. They continue to develop over the fall months and into the winter.

Bud Break

• Bud break occurs in the spring when the buds begin to swell on the tree branches and burst through the protective scales. This is often considered the official start of the leaf's growing cycle. The timing of bud break varies each year, depending on how long the cold weather lasts in the winter. During this time, the oak tree is coming out of dormancy and directing all of its energy and resources to growing new leaves and flowers. This means that oak trees are particularly vulnerable to insect attacks and other threats during this time.

Uncurling

• Oak leaves slowly uncurl and grow during the spring months. By the middle of summer, they are fully open, depending on the tree and locale. Some oak trees have leaves that open as early as late May, while others open much later, in early July. Once open, they begin to produce food.

Leaf Drop

• Oak leaves remain green until fall, when they change color. This is due to the slowing and stopping of chlorophyll production. In effect, the leaves stop making food and die, which is why the green color fades and the browns appear. Oak trees are not as colorful in the fall as other deciduous trees. Their leaves contain a lot of tannin, which makes them turn brown rather than vibrant orange, yellow or red. Some species of oak trees hang onto their leaves through the winter -- a process called marcescence. The leaves finally drop in the spring, displaced by the uncurling of the new leaves.