WHOLE CHARACTER
须
must; to have to (必须,务须); beard; moustache — facial hair (胡须,须眉); whisker-like parts (触须,须根)
须 xū has two separate jobs: must and need (必须), and — from the old beard character — whiskers (胡须, 触须).
ZDIC: 会意,从页、从彡 — the old form 頁 pictured a head, with 彡 as hair streaks (ZDIC: 彡 表毛饰): the beard face. Source caution handled: the modern 页 as a standalone word means page — that page meaning is NOT projected back onto the old head sense; the must/need sense and the beard sense are separate sense groups (the beard sense came through the old 鬚, merged into 须).