Section B. General Characters and Character States:
IX. Patterns

A. Symmetry

Actinomorphic or Radial. With floral parts radiate from center like spokes on wheel.

Asymmetric. Without regularity in any dimension.

Dorsiventral. Planate and having distinct dorsal and ventral surfaces, the two usually different.

Equilateral. With halves or sides equal in shape and size.

Inequilateral. With halves or sides unequal in shape and size.

Irregular. With floral parts within a whorl dissimilar in shape and/ or size.

Regular. With floral parts within a whorl similar in shape and size.

Spherical. With multi-dimensional radial symmetry.

Zygomorphic or Bilateral. With floral parts in two symmetrical halves.

B. Arrangement Systems
(Based on Leppik [1961])

Anthotaxis. Arrangement of sporophylls, primarily reproductive in function.

Carpotaxis. Arrangement of fruits, reproductive in function.

Phyllotaxis. Arrangement of leaves, primarily photosynthetic in function.

Rhizotaxis. Arrangement of roots.

Semataxis. Arrangement of semaphylls (petals, sepals, tepals), primarily advertising (pollinator attracting) in function.

Fibonacci Phyllotaxis. A fundamental type of leaf arrangement expressed as a fraction in which each succeeding fraction is the sum of the two previous numerators and the sum of the two previous denominators, i.e., 1/2, 1/3, 2/5, 3/8, 5/13, 8/21, etc. The numerator represents the number of turns or spirals around a stem before one leaf is directly above another and the denominator represents the number of leaves in the turns or spirals before one is directly above the other. 2/5 phyllotaxy would mean two twists and five leaves before one leaf is directly above the other or an angle of divergence of 144 between succeeding leaves in the stem (2/5 of 360 ). According to Leppik anthotaxis and semataxis do not necessarily follow the same pattern, with anthotaxis in Michelia cited as being in 2/7, 3/7, 3/8, and 4/10 systems of arrangement.

C. Branching Patterns (Figure 6-17-1)
(Adapted from Halle [1971])

Dichotomous. Branching into two equal parts.

Flabellate. Fan-shaped branching.

Monopodial. Branching with a main axis and reduced or missing laterals; excurrent.

1. Without lateral branches. Main axis ending in a cluster of large leaves; e.g., Carica papaya.
2. With continuous lateral branches. Main axis beset with laterals; e.g., Trema lamarckiana.
3. With continuous but self-pruning lateral branches (excurrent). Main axis with upper laterals present and lower having fallen off; e.g., Pinus.
4. With short-lived laterals. Main axis beset with phyllomorphic branches, appearing as compound leaves that may be deciduous; e.g., some tropical Rubiaceae, Pycnanthus.
5. With spiral or whorled main laterals on main axis and distichous branches; e.g., Pycnanthus.
6. With spiral or whorled main laterals and dichotomous branches; e.g., Phyllanthus.
7. With tiered or clustered lateral branches. Main axis with periodic lateral branch production; e.g., Bombax.

Sympodial. Branching without a main axis but with many, more or less, equal laterals.

1. Leader displacement. Successive laterals take over leader growth producing umbrella-shaped trees; e.g., Acacia, Melia.; deliquescent.
2. Leader displacement by two equal laterals (dichotomous substitution). Production of a forked branching system; e.g., Manihot.
3. Leader displacement as a short-shoot (apposition). Usually a single lateral becomes dominant; e.g., Terminalia.

Note: Other types of stem growth and branching patterns occur, particularly in tropical woody plants but no adequate classification has been devised.