Shen Collection, Upper Volume
Radical: Grass (cǎo)
Yu
Kangxi Strokes: 15
Page 1042, Entry 37
Tang Rhymes (Tangyun) and Rhyme Collection (Yunhui): Pronounced yu (rising tone).
Explaining Graphs and Analyzing Characters (Shuowen): Grass.
Also a surname.
Quick Reference (Jijiupian): Yu Duanqing.
Commentary: Yu is also the character for yu (a type of tree). Yu is the name of a tree; the surname was derived from the tree.
History of the Former Han (Qianhan): There was a Yu Zhang.
Also Rhyme Collection (Yunhui): Pronounced ju (rising tone). Meaning the same.
Also Collected Rhymes (Jiyun): Pronounced ju. That which is used to straighten a carriage wheel.
Rites of Zhou (Zhouli), Winter Officers (Dongguan), Wheel Maker (Lunren): Use yu to straighten it.
Commentary: This refers to a yulou used to rotate the top of the wheel; if the middle of the wheel has a yulou, then it will not be crooked.