From central–peripheral to adaxial–abaxial

Higher plants are constructed of three organs – the stem, the root and the leaf. The stem and the root have two axes, apical–basal and central–peripheral, which cross orthogonally. Leaves develop from the shoot apical meristem as lateral organs that have three different axes, apical–basal, adaxial–abaxial and right–left. Recent data point to the possibility that the adaxial–abaxial axis in the leaf is formed from the central–peripheral axis in the stem.