Oak tree in California with "shaggy" leaves growing from trunk
Living in the San Gabriel Valley, I'm used to seeing a wide variety of oaks, including so many varieties of California Live Oak species that I've never quite tried to learn all of them, but this particular tree looked so strange I couldn't help wondering if the growth habit was natural or a sign of disease/insect infestation (in which case, since it's planted in a public park with many other oak specimens, should I bring it to the attention of the parks department before the problem spreads?)
As you can see from the following photo, it's an old, well established tree (I'll post another separately that gives a closeup of one of the bark along with some of the green shoots visible at eye level). Its bark seemed almost corrugated, it was so rough and ridged, and quite grey as many California oaks are, but it was really the shaggy green growth along the bark that surprised and somewhat worried me. Can someone confirm whether or not this is normal for any oak species (and if so, just out of curiosity, which one?) or is it a sign of disease?