Buds and Budding

Plant buds, such as the buds of flowers, trees, and scrubs, are small, rounded, incompletely developed, dormant parts of a plant consisting of cells capable of rapid cell division when conditions are right for growth. They first appear in the spring when sap starts to flow, causing the buds to swell, which makes them more noticeable. These buds are first formed by the plant in late summer and early fall but remain small over the winter. When spring arrives, the structures for new shoot and floral growth are already formed and are tightly packaged and ready for quick growth when days lengthen and temperatures rise. The delicate, immature structures of these plant buds are covered with tough protective scales formed from modified leaves that enable the tender structures to get through winter in a dormant, resting state.

Plant buds can be classified in two ways, either according to their location on the plant, or according to the type of tiny immature structures that are contained within the bud. Buds on the tip of stems are called terminal buds, those at the sides of stems are called lateral buds, while those formed in the angle the leaf makes with the plant stem are known as axillary buds. When buds are classified according to their internal structures, those that contain only the beginning of a flower are called flower buds. Those that contain only immature leaves are called leaf buds, while those buds containing both flowers and leaves in the earliest stages of development are termed mixed buds. Flower buds on herbaceous plants and on woody plants are made up of undeveloped and tightly packed groups of cells that are the precursors of the various floral parts—petals, stamens, and pistils—with a whorl of sepals or outer leaf bracts covering and protecting the inner parts of the flower bud. Some small buds can produce a surprising amount of growth when attached to, and growing out from, a piece of the parent plant that is put into suitable soil. People familiar with growing potatoes by planting small sections of potato that contain "eyes" (sunken buds) know that the sprouts that grow from these buds will develop into whole new potato plants. Because of this remarkable ability for vegetative reproduction, these fertile pieces of potato are referred to as seed potatoes. The little sunken bud (the potato "eye") draws its nourishment to sprout from the stored starchy food contained in the piece of parent potato tuber.

The buds that woody plants such as shrubs, woody vines, and trees produce contain miniature shoots with a short stem and small, undeveloped, tightly packed leaves or immature floral structures covered with tough protective, overlapping scales. A terminal bud on a woody twig overwinters and grows out during the next spring and summer into a whole new shoot that extends the length of the twig and may also produce flowers. Apple and cherry blossoms are well known examples of this type of bud growth. Growth from a lateral bud will produce either a branch, or just a leaf on the side of the twig depending upon the nature of the precursor cells that were packaged in the bud during the previous fall.

A hydra, budding. © Biophoto Associates/Science Source/Photo Researchers, Inc.