nexine
/ˈnɛksɪn/ /ˈnɛksʌɪn/ /ˈnɛksiːn/Botany
noun
In the wall of a pollen grain or spore: the inner layer of the exine, lacking the sculpturing characteristic of the outermost layer (the sexine).
Origin
1940s. From n- (in non-sculptured) + exine: see quot. 1948.