Best known from 溆浦 (Xupu), a county in Huaihua, Hunan, named after the Xu River. The poet 屈原 mentions entering 溆浦 in the verse 'Crossing the River' from the Verses of Chu.
Three-drop water radical 氵, the side form of 水. It marks 溆 as a water word — a river name and the edge of a stream — alongside other river characters like 淄 and 漳.
phonetic
敍xù
to narrate; orderly (phonetic)
The right side is the 敘/叙 element supplying the sound xù exactly. The same phonetic body gives the reading in 叙 'to narrate', so the sound link is easy to remember.