TLDR: Axillary buds are little baby shoots that grow in the space between a leaf and a stem on a plant. They have the potential to become either branches or flowers.
Axillary buds, also known as lateral buds, are small shoots that are found in the axil of a leaf, which is the space between the leaf and the stem of a plant. Each bud has the ability to grow into a shoot, and it can specialize in producing either vegetative shoots (like stems and branches) or reproductive shoots (like flowers). Sometimes, the bud remains dormant for a while before growing, while other times it immediately forms a shoot.
Axillary buds are important because they contribute to the growth and development of a plant. However, they don't always become active shoots. This is because of a phenomenon called apical dominance, which is when the main stem of a plant grows more vigorously than the side shoots. The apical meristem, which is the growing tip of the stem, produces a hormone called auxin that inhibits the growth of axillary buds. This means that if the main stem is strong and dominant, the axillary buds won't grow. However, if the main stem is removed or if it's far enough away from the axillary bud, the bud can become activated and grow into a new shoot or flower.
Axillary buds can be affected by certain plant diseases, such as phytoplasmas, which can cause the buds to proliferate and make the plant appear bushy.
In summary, axillary buds are little shoots that grow in the space between a leaf and a stem on a plant. They have the potential to become either branches or flowers, but their growth is influenced by the main stem and the hormone auxin. Certain plant diseases can also affect the development of axillary buds.