Quercus agrifolia, wislizeni
Stem galls, bud galls or modified buds
Depressed sphere with nipple at apex and circle of white hairs at base when detached. Green while growing, not secreting honeydew. May. Fig 194.
Fig 194. Unknown. On Q agrifolia and wislizeni. A green smooth bud gall with a nipple at apex, almost hidden by bud scales. Has a circle of white hairs at base when detached. Found in northern California in mid-May. It is not Dryocosmus attractans (Kinsey) which secretes copious honeydew.
”- LH Weld: (1957) Cynipid Galls of the Pacific Slope©
Reference: https://babel.hathitrust.org/cgi/pt?id=coo.31924018313555&view=1up&seq=104