Phyllotaxy

The pattern of arrangement of leaves on the stem is called phyllotaxy. There are three main types of phyllotaxy.

Alternate or Spiral

In this type, a single leaf arises at each node. The consecutive leaves are produced in a spiral manner around the stem. e.g. Polyalthia, Hibiscus, etc.

Opposite

In this type, the leaves are arranged in pairs at each node.

When the opposite leaves arise in the same plane at successive nodes, it is said to be opposite superposed phyllotaxy. e.g., Quisqualis.

When each opposite pair of leaves are at right angles to each other, phyllotaxy is said to be opposite decussate. e.g., Calotropis Ixora

Whorled Phyllotaxy

If more than two leaves occur at a node, the phyllotaxy is said to be whorled. e.g., Nerium.

fig. 27.37 - Types of Phyllotaxy