bright, shining, splendid
苪 centers on radiant light: something bright, shining, or splendid. The meanings all describe a vivid, luminous quality.
苪 is a rare character. It combines the plant radical 艹 with 丙, which may have contributed a sound element. The exact historical development is uncertain.
The top 艹 suggests a plant, and the bottom 丙 looks like a bright, open space. Imagine a splendid flower shining in the sunlight.
For ヘイ, picture a bright hay field under the sun: hay -> ヘイ, and the shining plants make the field splendid.