The study of cryptogamic plants (especially fungi, slime molds, and fresh-water algae) was one of the life-long researches of Kumagusu. From childhood, he soaked up knowledge about plants from books and in the fields. At the age of 17, he knew of the existence of the collection of 6,000 specimens of fungi in the U.S.A., and was determined to collect more than that in Japan.

Kumagusu began collecting plants seriously while staying in the United States, and when he returned to Japan, he put his research efforts into cryptogams and other plants. Minakatella longfilia, a slime mold which he discovered in his own garden, was described as a new species.

He continued to increase his collection of specimens through his life. However, he was not able to publish his collection of Japanese fungi within his lifetime.

<strong>Kumagusu’s Plant Specimens</strong><br> In addition to slime molds and fungi, Kumagusu was interested in many different plants and collected them as well.<br> He left behind nearly 6,600 slime mold specimens, 7,600 fungi specimens, 5,000 fresh-water algae specimens (including those prepared on glass slides), 1,570 moss specimens, 700 lichen specimens, and 7,800 spermatophyte (flowering) plant specimens.
Kumagusu’s Plant Specimens

<strong>A specimen of dune stinkhorn (Phallus hadriani) </strong><br> Kumagusu had never seen this kind of mushroom before, and was interested in its unique smell and peculiar shape.
A specimen of dune stinkhorn (Phallus hadriani)

<strong>Prepared Fresh-Water Algae Specimens</strong><br> Algae, and in particular fresh-water algae, made up a major portion of Kumagusu’s biological research besides fungi and slime molds.<br> This group had been relatively less studied in Japan by that day, as many species of fresh-water algae are of microscopic sacle.<br> Kumagusu spent many hours collecting and preparing specimens; he prepared roughly 4,000 slides. He also made dried specimens.
Prepared Fresh-Water Algae Specimens

<strong>A specimen of Uga, a kind of barnacle stuck on a sea snake’s tail</strong><br> This is the specimen that Kumagusu explained first when he gave a lecture to Emperor Shōwa in June 1929.
A specimen of Uga, a kind of barnacle stuck on a sea snake’s tail