Snowflake
雪華 sekka

Snow crystals drawn after Doi Toshitsura's Sekka Zusetsu (1832) became an Edo fashion; like snow in general they promise a rich harvest.
1832, Koga domain (Ibaraki); Edo fashion in the 1830s–40s
Doi Toshitsura, daimyō of Koga, spent years observing snow crystals through an imported Dutch microscope and published 86 drawings as Sekka Zusetsu in 1832, with a sequel in 1840. Though made for his own circle, the drawings were soon copied onto textiles and other goods, and snowflake (sekka) patterns became popular among ordinary people in Edo.
Sekka is a winter motif but, like yukiwa, its cool look also appears on summer yukata.