Epilogue: After urbanization and endangered Asarum tamaense Makino

 

Stachyurus praecox in Tama Hill

In 1931, Dr. Tomitaro Makino (; my post on October 27, 2023) named a species of Asarum (; my post on May 6, 2022) found in Kawasaki. It is called Asarum tamaense Makino. As it is in the genus of evergreen Asarum, it loves humid forests with leaves sprout out straight from the ground and flowers with brownish calyx stick to the soil. Asarum can move VERY slowly from the place parent plants locate. Estimated speed of its movement is about 1 or a couple of kilometers per 10 thousand years. i.e., it has time to evolve adjusting to a particular environment where the “original” established (literary) its roots. Actually, Japan has 50 known independent species of Asarum each of which is exclusive to a very limited geographical area, similar to Darwin finches in Galapagos. In 2020, a team of botanists led by Dr. Yudai Okuyama of National Museum of Nature and Science published in Annals of Botany their findings from DNA sequencing for almost all (mainly) Japanese Asarum. They theorized when Japanese archipelago was a part of Eurasian Continent 7 to 10 million years ago, the ancestors of these local Asarum moved from a part of now-China, and diversified their DNA pattern suitable for each distinctive environment where they stay for a very long run. Environments of Japanese humid forest floor can be different even between the neighboring small valleys, and hence we have many species of Japanese Asarum. Asarum contributes to a high biodiversity of Japanese nature.

Asarum tamaense Makino
 in a forest of Kanagawa Prefecture.
I won‘t tell you where I found them.

For the case of Asarum tamaense Makino, it has adjusted the climate of suburban Edo (aka Tokyo) whose soil is fluvial strata created by Tama and Tsurumi Rivers + volcanic ash from Mt. Fuji. DNA-wise it is locally very unique species spreading on the eastern edge of Fossa Magna region. Asarum tamaense was once ubiquitous in Tama Hills and little bit of Sayama Hills. Oh, by the way, it was the area where a massive housing development occurred during the 1960s and the 1970s. Please guess what happened to Asarum tamaense. Nowadays it’s a rare occasion finding Asarum tamaense in local neighbourhoods. Many survived Asarum are in college campuses where professional botanists roam, or in town where the landlords close the access to their land ... Moreover, as Asarum genus loves humid forest floor, drying ground accelerates the demise of their species. For example, if you leave ordinary forest on Tama Hills without proper management, sasa bamboos cover the floor completely. The spread of sasa roots over the surface of ground obstructs rainwater to seep in. Asarum tamaense will die for thirst. Now, Asarum tamaense Makino is nationally designated Endangered Species.

Once
people become not caring about forest floor in Tama Hills,
Sasa bamboos dominate.

The story of Asarum tamaense Makino is related to the issues surrounding Yokohama‘s Citizen Forest, don‘t you think? Normally, they flower in April, but in this boiling climate it might be earlier this year ...

Flowers of Japanese raspberry
which flower the same time as Asarum tamaense Makino.
I took the photo in Tama Hills.

If you have any questions about Yokohama’s Green Tax and Green Up Plan, please make a contact with

Strategic Planning Division, Green Environment Bureau, City of Yokohama
横浜市みどり環境局戦略企画課

Phone: 045-671-2712
FAX: 045-550-4093 

Email: mk-kikaku@city.yokohama.lg.jp