axil

An axil is the angle between a leaf (or its petiole) and the stem at the point where the leaf joins the stem. In plant morphology, the term describes the location on the axis where structures such as axillary buds, branches, inflorescences, or thorns commonly develop.

An axillary bud resides in the axil and represents a potential shoot meristem. These buds may remain dormant for periods of time or activate to form a lateral shoot or a flower cluster, depending on species and environmental conditions. The activity of axillary buds contributes to the branching pattern and overall architecture of a plant. Hormonal signals, particularly those involving auxins from the apical meristem, influence whether an axillary bud remains suppressed or grows (a phenomenon known as apical dominance).

In horticulture and pruning, understanding axils helps explain how pruning or damage to the main stem can stimulate new growth from axillary buds, shaping plant form and productivity. Some inflorescences or thorns also arise from the axil, depending on the species.

Etymology and usage: The term derives from the Latin axilla, meaning armpit, reflecting the metaphor of a corner or junction where a leaf attaches to the stem. The word axil is widely used across flowering plants, shrubs, and trees to denote this specific anatomical position.