The hybrid that isn't?

In the Southeastern USA live oak (Q. virginiana) hybridizes with three other oaks, at least according to Oaks of North America:  Overcup oak (Q. lyrata), post oak (Q. stellata) and swamp white oak (Q. bicolor). 

In one respect these hybrids are not supposed to happen.  Live oak is considered, by virtue of being evergreen and using the "modern" convention (at least it was modern as of the 1985 printing of my copy of Oaks) of grouping all evergreen oaks together, to be a Red/Black oak (Erythrobalanus).  Its three dance partners listed above, of course, are firmly placed in the White oak group (Leucobalanus).

But these are clearly artificial designations.  All of these oaks have acorns that mature in one year, so it makes sense that, at least in that regard, live oak is more of a white than a red.

Now come with me to the west coast.  Coast live oak (Q. agrifolia) is the dominant (in a bonsai sort of way) tree in my area.  Go a few miles inland and you quickly begin to find California white oak - a.k.a. valley oak (Q. lobata) mixed with coast live oak on the golden hillsides.

Both have acorns that ripen in one year.  It is, to say the least, a very romantic setting.  Morning fog, sunny afternoons, ocean views, wine country.  So of course the local hillsides resound with the pitter patter of roots of little Q. agrifolia x lobata hybrids, right?

Wrong.  I can't find any mention of such a hybrid existing.  And you'd think it wouldn't be hard to notice: An evergreen oak but with the lobed leaves of a valley oak, or a decidious oak with the bristled, cupped leaves of a coast live.  But apparently you don't, or at least no one has.

So yes, the stage is set for Q. x siemsii.  I know it's out there, I just need to find it.

Then again it might not be out there.  Instead of marrying the girl next door, coast live oak apparently goes gallivanting around the interior with California black oak (Q. kelloggii), a clear Erythrobalanus whose acorns mature in two years.  This apparently frequent union results in Q. x ganderi C.B. Wolf or Q. x chasei McMinn, Curly and Moe - depending on where you are and who you talk to.  And their parents said it would never last! 

It's got me wondering about the whole red oak / white oak division and what it means.  My guess: Not much.