Botany · Ch 3 — Vegetative Morphology
Phyllotaxy
Phyllotaxy
Phyllotaxy (Greek phyllon = leaf, taxis = arrangement) is the pattern in which leaves are arranged on the stem, and it functions to avoid overcrowding while exposing the maximum leaf area to sunlight for photosynthesis. There are four main types. In alternate phyllotaxy each node bears a single leaf, with successive leaves alternating up the stem; if the leaves spiral around the stem it is alternate spiral (Hibiscus, Ficus), and if they lie in just two rows on opposite sides of the stem it is alternate distichous/bifarious (Monoon longifolium, syn. Polyalthia longifolia). In opposite phyllotaxy each node bears two leaves facing each other; if successive opposite pairs lie in the same plane, directly above one another, it is opposite superposed (Psidium/guava, Eugenia jambolana, Quisqualis), and if each pair is set at right angles to the pair above and below it, it is opposite decussate (Calotropis, Zinnia, Ocimum). In ternate phyllotaxy three leaves a …
What this figure shows. Five phyllotaxy patterns on stem diagrams: Alternate phyllotaxy in Polyalthia - a single leaf per node, arranged spirally up the stem; Opposite superposed phyllotaxy in Guava - pairs of opposite leaves at successive nodes lying directly above one another; Opposite decussate phyllotaxy in Calotropis - each pair of opposite leaves set at right angles to the pair above/below it; Ternate phyllotaxy in Nerium - three leaves arranged at every node; Whorled phyllotaxy in Allamand …