The order or arrangement of leaves on the stem; the science of the relative position of leaves.

or phyllotaxy - (Gr. Phyllo - leaf + Taxis - arrangement) The study of the arrangement of repeated units such as leaves around a stem, scales on a pine cone or on a pineapple, florets in the head of a daisy, and seeds in a sunflower. Also refers to specific arrangements (e.g.. (3,5) spiral phyllotaxis). The main different types of phyllotaxes are spiral, multijugate, distichous and whorled - the last two can be seen as special cases of the first two. Plastochrone ratio (R) - ratio of the distance of two consecutive primordia from the center of the apex Primordia - Microscopic bulges of cells initiating around the apex meristem. Primordia evolve into the different botanical elements of a plant (leaves, petals etc.). Rising phyllotaxis - spiral phyllotaxis with increasing parastichy numbers.

leaf arrangement on the stem, e.g. decussate, spiral etc.