axil of petiole in both simple and compound leaves, but not in the axil of leaflets of the compound leaf. The compound leaves may be of two types (Figure . ). In a pinnately compound leaf a Figure .
Structure of a leaf : (a) Parts of a leaf (b) Reticulate venation (c) Parallel venation (b) Silk Cotton Lamina Petiole Stipule Leaf base Axillary bud (a) Neem Figure . Compound leaves : (a) pinnately compound leaf (b) palmately compound leaf Rachis number of leaflets are present on a common axis, the rachis , which represents the midrib of the leaf as in neem. In palmately compound leaves, the leaflets are attached at a common point, i.e., at the tip of petiole, as in silk cotton. .
. Phyllotaxy Phyllotaxy is the pattern of arrangement of leaves on the stem or branch . This is usually of three types – alternate, opposite and whorled (Figure . ).
In alternate type of phyllotaxy , a single leaf arises at each node in alternate manner, as in china rose, mustard and sun flower plants. In opposite type, a pair of leaves arise at each node and lie opposite to each other as in Calotropis and guava plants. If more than two leaves arise at a node and form a whorl, it is called whorled, as in Alstonia.