This Glossary sometimes refers to the main text, but the reader is encouraged to consult the indexes in order to locate text references to the terms defined here.

Accessory sequence: Any one of the sequences of normal phyllotaxis with t > 2, such as the Lucas sequence where t = 3. The term “accessory”is relative to the main sequence, which is the Fibonacci sequence where t = 2.

Acropetal: Toward the apex.

Angiosperms: Seed plants in which the seed is enclosed in a fruit. In the gymnosperms (conifers) the seeds are naked (gymno) on scales, which are arranged on cones.

Angle of intersection γ (of a parastichy pair): The angle made by two parastichies in a parastichy pair.

Anomalous phyllotaxis: A system shows anomalous phyllotaxis when the visible opposed parastichy pairs of the system are made with consecutive terms of the sequence of anomalous phyllotaxis (obtained from the model of Chapter 6), that is the sequence 〈2, 2t + l, 2t + 3, 4t + 4, …〉, where t ≥ 2 is an integer. Putting t = 2, 3, 4,… gives respectively the first lateral sequence 〈2, 5, 7, 12, 19, …〉, the second lateral sequence 〈2, 7, 9, 16, 25, …〉, the third lateral sequence 〈2, 9, 11, 20, 31, …〉, ….

Apex (shoot apex): The center of a bud where leaf or reproductive primordial are formed. The center of morphogenesis in vascular plants, giving rise to stem, leaves, and flowers. Leaves originate as leaf primordial on the flanks of the shoot apex.