蝦夷方言藻汐草

sirar is well attested for rocks, including seashore rocks, and Hirayama compares sirari in that terrain sense. The Japanese 泻 remains ambiguous: related 瀉 can concern flowing/pouring or saline ground, while 潟 concerns tidal flats or lagoons. These comparisons do not securely equate the heading with a rocky shore. The alternative sirari also has an independently attested sake-lees homonym, which does not fit this terrain context. Retain sirar provisionally without replacing the Japanese character.