| Definition: |
An axis of a plant structure that is determined by the direction of apical growth, either by an apical meristem or an apical cell. Apical is toward the direction of apical growth: toward the tip of a growing shoot axis, root, thallus, or non-vascular leaf. Basal is away from the direction of apical growth: toward the root-shoot junction in the case of the primary root or stem, toward the primary root or stem for higher order roots or branches, toward the point of attachment for non-vascular leaves, and toward the original point of growth (as determined in the embryo) for thalli. |