Bud is a cluster of developing leaves surrounding a growing point of a plant. This growing point is called an apical meristem. The apical meristem within each bud contains the cells that divide and grow to form new leaves, flowers, and stems.
Buds of most woody plants are covered by overlapping modified leaves called bud scales. Bud scales preserve water and protect the delicate tissues within the bud. During the winter, the buds of many woody plants are dormant (inactive). In the spring, the leaves within buds resume their growth, and the expanding leaves on the lengthening shoot sprout from the bud. Later in the season, new leaves gradually form around each meristem’s base, forming next year’s buds.
On many plants, a terminal bud is found at the tip of each shoot. On some plants, lateral buds form along the sides of stems. These buds normally develop above the points where a leaf joins a stem. These points are called nodes, and the marks left where leaves break away from the stem are called leaf scars. Lateral buds that form elsewhere on a stem are adventitious buds. Sometimes adventitious buds develop in response to injury.
Most woody plants can be identified by the shape, size, color, and position of their buds. Buds of woody plants may contain leaves or flowers or both leaves and flowers. Leaf buds and flower buds on the same plant can be distinguished by their different shapes and sizes.
Individual flowers, before they bloom, also are called buds. The outer covering of most flower buds consists of leaflike sepals, which form the calyx (see Flower (The parts of a flower)). Some flowers, such as tulips, grow at the tips of shoots. Other flower buds form laterally on stems above regular or modified leaves called bracts.
Heads of cabbage and Brussels sprouts are enlarged leafy buds. Broccoli and cauliflower heads consist of many tiny flower buds.
