Quercus rugosa x macrocarpa | Palo Alto
Now that we have looked at the natural range of genetic variation within the "species" Netleaf Oak (Q. rugosa), we can step into the chaos of Netleaf Oak hybrids. At the Shields Grove, Netleaf Oak grows surrounded by many reproductively-compatible oaks. A centrally-situated Netleaf Oak at Shields produces copious acorns, and the array of trees which have grown from these acorns is truly dizzying. Here we see a hybrid from the Shields Grove Netleaf Oak, growing in the hills near Palo Alto. The presence of a central sinus in the leaf is a giveaway that the paternal parent of this tree was almost certainly Bur Oak (Q. macrocarpa), or its hybrids, which are very common in the Shields Grove, and could easily provide pollen. Regardless of parentage, the leaf is aesthetically interesting, and many of they hybrid forms tested have proven robust and survivable.