1. About the species of Japanese Digitaria-plants were studied from physiological and ecological standpoint. 2. The writer found three special different types of specimens which were respectively estimated as Digitaria adscendens Henr. by authoritative taxonomists. But they had many characteristics different from the plants which the writer took up the typical form, or commonly seen normal type, of D. adscendens Henr. so that he named them (a) Glabrous type, (b) Slender type and (c) Intermediate type.