phyllotaxis
Phyllotaxy is the order in which leaves or twigs are implanted on the stem of a plant or, by extension, the arrangement of the elements of a fruit, flower, bud or capitulates. Phyllotaxy is also called the science that studies these arrangements. There are several types of phyllotaxies, which depend on: ▪ the number of leaves per knot ▪ the arrangement of these leaves along the stem. Number of sheets per node: One sheet per node The layout is called alternate. When these leaves, along the stem, are on a plane, this is called a disticular alternate phyllotaxy. When these leaves, along the stem, are arranged all around the stem, this is called an alternate phyllotaxy spiral. Two sheets per node The arrangement is said to be opposite. When these leaves, along the stem, are on a plane, this is called an opposite phyllotaxy. When these leaves, along the stem, are arranged perpendicularly from one node to the other, this is called a contrasted opposite phyllotaxy.