According to the writer's investigations of the leaves of one hundred and eighty seven Carices, the anatomical characteristics may be divided in following three types. 1. A certain characteristics appear parallel with the resemblances of the outer features. 2. The characteristics are unique in the species (so far as in the writer's observations). 3. Common characteristics appear in some species, but they have not the systematic meanings for grouping them, these cases occur most frequently. By using the characteristics on the leaves, we can constract the analytical keys to distinguish these species; the facts show us the systematic importances of the present studies, and also the usefulness for the determination of the imperfect specimens.