Unknown gall.
Quercus chrysolepis
Leaf galls, integral
Conical, red, 2-10 mm long, surface above it depressed. Fig 170. The terminal cluster of similar galls in Fig 126 may be the same thing.
Fig. 126. Q. chrysolepis. This is thought to be a cluster on an aborted leaf. A single one on a leaf is shown in Fig. 170.
Fig 170. Conical, red, on under side of leaf of Q. chrysolepis; above it the leaf surface is depressed. Single or in a cluster on aborted leaves so that it looks like a stem gall (Fig.126). Full-grown in June. Those collected in September to December have been empty.
”- LH Weld: (1957) Cynipid Galls of the Pacific Slope©
Reference: https://babel.hathitrust.org/cgi/pt?id=coo.31924018313555&view=1up&seq=85