Hybrid cork oak - in this case Q. suber x Q. cerris 'Luscombeana' - already exists. And is present in at least two Seattle collections. See Jacobson, Trees of Seattle - Second Edition, p. 285.

Otherwise there is Q. hypoleucoides - a feature at the Carl English Garden (government locks) in Seattle - and numerous other dry climate adapted, evergreen oak species with attractive foliage features. Along with pines oaks are the main trees of many Mediterranean climate areas - including California, to name one that is comparatively nearby.

They aren't in the same section so I'm pretty sure they will not cross; that's why the existing western European evergreen hybrid oaks are:

Quercus X turneri (white oak section, it is English X Holm oak)

and

Quercus × hispanica (cerris section; referenced by embo above)

So, these 2 hybrids are already what you are looking for; either recreate them or try to get scions from Europe. You probably can't reinvent the wheel in this case, just turn a new one... ;-) IIRC, Jacobson in NALT says Turner's oaks are ugly and gaunt in the PNW; so I'd focus on recreating the latter cross. OR see if you can get scions from the trees he mentioned. Assuming you like the look of them.

Even plain old Q. suber or Q. ilex though, should be green in most PNW winters, and plenty drought tolerant. Not sure you really need to cross them with anything else.

I myself want to cross Q. variabilis with Q. suber to create an evergreen cork oak that would be more tolerant of eastern US conditions. That of course doesn't help you since you don't have the wet summers that Q. variabilis clearly likes. It occurred to me after my prior post on this subject (which I DO NOT want to be further bumped) is that, in fact, our southern US live oak is in the white oak section along with Q. ilex - the Holm oak. So to get the extra hardy and eastern-tolerant Holm oak I'm looking for, I really ought to try to cross Q. ilex X Q. virginiana var. fusiformis; i.e, the extra-hardy ones collected in OK, or any other known hardy Q. virginiana.

" The legendary discovery of Ambrozy's wintergreen oak in an old plantation of sweet chestnuts at Horné Lefantovce near Nitra in 1909 has a similar history. According to the legend one day in February some woodcutters were seen in a tavern wearing sprigs of green oak in their hats. This alerted Jozef Misák to the existence of a special tree growing near the garden of a former monastery. The tree was probably a hybrid of an evergreen oak (Quercus suber L.) crossed with a deciduous oak (Quercus cerris L.) Although there was initial talk of an acclimatized cork oak, its hybrid origin has now been confirmed as definite. Sadly, all the trees of this kind that had subsequently been grown at Mlynany disappeared from the arboretum after it came under state control. Ambrózy had propagated it profusely and it is thought that as many as 200 of them once grew in the park. Today the arboretum has only one specimen which was reintroduced from stock held by the well-known Hillier Arboretum in England. "

http://www.arboretum.sav.sk/sk/navstevnici/general-information/history/

The picture of the leaves does look like it is a cross of Q. suber. If that is a hybrid between Q. suber and Q. cerris, and if Q. cerris can hybridize with Q. robur, then it would stand to reason that Q. robur would be capable of hybridizing with Q. suber.

Lucombe oak is believed to be a hybrid between Q. cerris and Q. suber, and is grown in many botanical gardens.

"Putative hybrids between Q. cerris and Q. robur have been recorded in Britain - currently the subject of an MSc research project" although at the bottom they write that these suspected hybrids could only be the pure species Q. cerris.

http://sppaccounts.bsbi.org/content/quercus-cerris-1.html

" crosses in progencies from three Q. ilex x Q. suber hybrid trees in mixed forests. "

https://www.google.com/url?sa=t&source=web&rct=j&url=http://www.euforgen.org/fileadmin/templates/euforgen.org/upload/Publications/Thematic_publications/Quercus_suber_OpenSourceCR_web.pdf&ved=0ahUKEwiNn4OspZHXAhUBxWMKHW1_AjIQFggtMAE&usg=AOvVaw39vkA5wJxsvGGvGKNln7HZ

Q. ilex x Q. robur hybrid:

http://onlinelibrary.wiley.com/doi/10.1111/j.1365-3040.2003.01169.x/full

The results of the experiment are strong evidence that this is indeed a hybrid between the two species.

"It turned out that the Q. ilex x Q. suber mating resulted in a seed set of 25%, while the reciprocal cross did not result in any accorn production (Table 2.1). This was attributed to inability of pollen tubules of Q. ilex to penetrate the stigmatic surface after germination." (p22)

http://www.euforgen.org/fileadmin/templates/euforgen.org/upload/Publications/Thematic_publications/Quercus_suber_OpenSourceCR_web.pdf

(they also reference Staudt 2004)

Hhhmmmm. So oaks can cross across some sections but probably not others. Good to know. Maybe, as with the subgenus crosses of Rhododendron, they are difficult to make and guaranteed sterile. The Turner and Lucombe oaks are definitely not sterile.

If the Slovak arboretum "replenished" with a plant from Hilliers, you'd surely have to wonder if it wasn't just a regular old English 'Lucombe' oak. Why would they have the ones from Nitra? Seems unlikely.

Thanks for the interesting links, btw.

Fair use quote from your second link:

Although the genus Quercus is notorious for hybridisation, it
usually occurs between more closely related species, that is within the
same taxonomic group known as sections. Q. cerris and Q. robur are in different sections of subgenus Quercus
- section Cerris and section Quercus respectively. A study invloving
DNA analysis with nuclear microsatellite markers has provided molecular
evidence suggesting these possible hybrids are in fact the pure species,
Q. cerris, with confusion seemingly having arisen due to the extreme variability in leaf shape of Q. cerris,
(McGinn 2010). This conclusion is supported by the opinions of many
botanists in disallowing older records of the putative hybrid, e.g.
Stace 2010.

So, it's pretty clear that at least Q. cerris X Q. robur hasn't been proven, and may have been disproven.

did you see this?

http://onlinelibrary.wiley.com/doi/10.1111/j.1365-3040.2003.01169.x/full

Q. ilex can hybridize with Q. robur, and Q. ilex can also hybridize with Q. suber, apparently.

(implication: maybe Q. robur can be compatible with Q. suber)

according to Wikipedia:

" Q. × turnerii Willd. (Q. ilex × Q. robur) (Turner's Oak), a semi-evergreen tree of small to medium size with a rounded crown; it was originally raised at Mr. Turner's nursery, Essex, UK, in 1783. An early specimen is at the Royal Botanic Gardens, Kew. "

from the earlier article:

" Quercus × turneri ‘Pseudoturneri’ is a hybrid between Quercus ilex L. and Quercus robur L. originally produced in England at the end of the nineteenth century. Three individuals of this hybrid are growing in the Arboretum of the BFH, Institute for Forest Genetics and Forest Tree Breeding, Großhansdorf, Germany. "

" The present study clearly demonstrates that introgressive hybridization between a monoterpene- and isoprene-emitting oak species results in a mixed isoprenoid emission pattern combining the isoprenoid chemo-type of both parental species. "

Plant, Cell & Environment, Hybridization of European Oaks (Quercus ilex x Q. robur) results in a mixed isoprenoid emitter type, J.P. Schnitzler, R. Steinbrecher, I. Zimmer, D. Steigner, M. Fladung, Volume 27, issue 5, May 2004, pages 585-593,

(implication: maybe Q. robur can be compatible with Q. suber)

Well maybe. Anyhow from skimming both articles it seems those bi-sectional oak hybrids are hard to produce, and do not actually have the anticipated hybrid vigor which is seen in the 'intrasectional' hybrids. One was said to be a dwarf. But good luck with your project, let us know how it goes.

Hybridization between different sections of oak are possible, but apparently only if Q. suber is acting as the pollen parent.

http://www.nature.com/hdy/journal/v102/n5/full/hdy20098a.html

https://link.springer.com/article/10.1007/s004970100100

https://www.ncbi.nlm.nih.gov/pubmed/11555243

Although Q. ilex is a Mediterranean evergreen oak, it is grouped together in the White Oaks section with Q. robur.

Q. suber is grouped under the section Cerris.

"The presence of fertile oak hybrids resulting from interspecific crossing between more than 500 species recognized in the genus is well-known, and has been extensively documented (Govaerts and Frodin 1998 ). The inter-sectional hybrids in Quercus L., are frequently sterile, such as Q. robur (Sect. Robur) cross to Q. suber (Sect. Cerris) ... " It goes on to say that, of the more than 300 oak hybrids that have been acknowledged, 70% of them are fertile, capable to generate viable offspring, and showing the ability to backcross.

Oaks Physiological Ecology. Exploring the Functional Diversity of Genus Quercus L. , edited by Eustaquio Gil-Pelegrín, José Javier Peguero-Pina, Domingo Sancho-Knapik, p241

Oaktopia, thanks, interesting website for sure. Bookmarked.