axils

An axil, in botany, is the angle between the upper side of a leaf (or a branch) and the stem from which the leaf arises. The leaf axil is the region at the junction of the leaf and stem, and it houses the axillary bud, a meristematic tissue capable of developing into a lateral shoot or an inflorescence. The axillary bud may remain dormant for periods or grow to form a secondary shoot, depending on genetic programming and environmental cues such as light, temperature, and damage to the plant.

In many plants, the activity of axillary buds determines branching pattern and plant architecture. Vegetative shoots produced by axillary buds increase the number of stems, while axillary inflorescences contribute to flowering and fruiting. Horticultural practices frequently target axillary buds through pruning or disbudding to shape plants and control fruit load.

The term axil also applies to the general region where a leaf attaches to the stem, and the concept is used to describe the site of potential growth along all parts of the plant, including twigs and branches. Etymology: from Latin axilla, meaning armpit, reflecting the angle at the junction.