Cool-Climate Plants and Ice-Age Survivors
Some of the plant species found in Kushiro spread to Hokkaido from Eurasia during the glacial periods of the last ice age. Many of these are normally found in alpine environments, but have survived in the Kushiro Wetlands because of its cool climate and the frequent fog that blankets the area in summer.
Flowers of the wetlands
During summer, the wetlands are dotted with the delicate purple flowers of the Kushiro hanashinobu (Polemoniaceae), a variety of phlox. This is a variation of a subspecies that grows on the island of Sakhalin to the north, and likely spread to Hokkaido during the ice age.
Cuckooflower (Cardamine pratensis) flourishes in the wetlands of eastern Hokkaido. It is also found in parts of the Eurasian continent and North America, suggesting that it, too, arrived in Hokkaido during the last ice age.
Mysterious marimo
Marimo are rare spherical growth forms of a species of freshwater algae (Aegagropila linnaei). Water motion can cause these filamentous algae to grow in spheres, attaining a size of up to 30 centimeters in diameter. The algae filaments grow in Lake Shirarutoro and Lake Toro on the outskirts of the Kushiro Wetlands, but the spherical marimo are only found in northern Kushiro’s Lake Akan.