adlay, plantain
苡 refers to specific plants: adlay (a grain-bearing grass) and plantain (a broad-leafed herb). The character centers on these two plant types.
苡 combines the plant radical 艹 with 以, which likely provides the sound. The character is used for plant names, but the exact historical development is uncertain.
The grass top 艹 sits above 以, like a plant growing from a base. Picture adlay stalks and plantain leaves sprouting from this shape.
For イ, imagine an eagle (イーグル) perched on the plant: eagle -> イ, and the bird rests among the adlay.
coix seed (used in traditional Chinese medicine)