The mode of arrangement of leaves on the stem and its branches is called phyllotaxy (phyllon-leaf; taxis-arrangement). They are arranged most systematically, regularly and mathematically, so as to get proper sunlight and avoid overcrowding.
Phyllotaxy in leaves is offollowiny three types
(i) Alternate A single leaf arises at a node, e.y., China rose, mango, mustard, sunflower, etc.
(ii) Opposite Two leaves arise at a node, opposite to each other, e.y., Guava, Calotropis tulsi, etc.
(iii) Whorled More than two leaves arise at each node forming a circle or whorl,
e.y., Alstonia Scholaris, etc.