Tree Blog

((Q. macrocarpa x robur) x lobata) x lobata | Valley Springs

Calaveras Nursery is located in existing oak woodland, including both Q. lobata, Q. douglasii, and the hybrids between them, often referred to as Q. x jolonensis. In their midst grew the large oak pictured on the previous page, meaning any acorns on the the large oak could easily be hybridized with the native oaks. When hybridized with Q. lobata, which some of the seedlings clearly appear to be, they are considered back-crossed, F2 hybrids. If the previous characterization of the origin of the large oak is correct, then the full name of these seedling tree is ((Q. macrocarpa x robur) x lobata) x lobata. The bristles, or burs, present on the acorn cups pictured show clear Q. macrocarpa parentage. The length and pointedness of the acorns themselves is quite reminiscent of Q. lobata, but their size is clearly derived from Q. macrocarpa. Although not visible in this photo, the acorn cups do have short peduncles, the one visible hint of its Q. robur parentage.


Dave Muffly