your oak
Bonhe
Nice tree. Usualy cork oaks are pretty straight, so when you get one with movement, it's a keeper.
The fissures on the trunk are where growth is happening. When the tree grows and puts out new corking, you get this fissuring. In a few months it will turn grey and blend in with the rest of the bark.
The swelling or wart like ball growing is a gall. It means that probably a tiny wasp has laid an egg, and the tree has grown tissue around it to isolate it in case of a disease or irritation. Similar to a pearl in an oyster from a grain of sand. It can happen to many kinds of trees, but its very common in oaks.
Your tree is either growing under or near a big native oak or was in the recent past. Ted Matson sold me a nice live oak that was full of galls from the big live oak in his yard. I cut the galls off, and since I have no native oaks growing near me, it has not returned.
Please relax, its perfectly harmless. Sometimes they even give an oak a wild character. It will not harm your tree or any others in your yard. If it bugs you, just cut it off.
Is the the person you got the tree from Richard Ota, who currently lives in Riverside Ca?
He is know for cork oaks and pomagranites.
I have a huge cork oak that Richard planted as an acorn along with a few others in the mid 50's. It's gonna be one of the best around when I get the foilage developed again. This tree was being showed in the 70's and 80's, but then had some problem and most branches died back. I am in the process of re-developing it. It's got super old looking corking. The other oaks Richard planted at that time have not survived, and it makes this one very special and I'm very lucky to have it.
Please take care of yours well. Someday it will be a piece of Bonsai history in the USA and California especialy.