PROTEIN AND IRON COMPOSITION OF COWPEA LEAVES: AN EVALUATION OF SIX COWPEA VARIETIES GROWN . IN EASTERN AFRICA . Okonya JS* 1,2 and BL Maass 1,3 . Joshua Okonya *Corresponding author email: 1Institute of Agronomy in the Tropics, Georg August Universität, Grisebachstr. 6, 37077 Götttingen, Germany