A floristic study of the aerial and soil algae of the Ryukyu Islands by means of crude cultures has taken.
1) Fourty-one genera and fourty-seven species including twenty-three species of Chlorophyceae, eighteen species of Cyanophyceae, two species of Xanthophyceae and four species of Bacillariophyceae are recognized.
2) The following algae are abundantly found in the Ryukyu Islands ; viz. Gloeothece rupestris (LYNGB.) BORNET, Phormidium tenue (MENEGH.) GOMONT, Calothrix elenkii KOSSINSKAJA, Westiellopsis prolifica JANET, Nitzschia obtusa W. SMITH var. scalpelliformis GRUNOW and Hantzschia amphioxys (EHRENB.) GRUNOW.
3) The soil algal community of calcareous soil region is dominated mostly by cyanophycean algae, however, the certain chlorophycean and xanthophycean species e.g. Stichococcus bacillaris NAEG. and Monodus subterraneus PETERSEN which are common algae in the acidic soil region of Honshu, Japan are restricted their distribution within the northern part of the Okinawa Island.