Quercus trojana | Davis
This photo displays a comparison of the timing of fall color between long-growing season Mediterranean Oaks, and short growing season Bur Oaks (Quercus macrocarpa) from the midwestern United States. The Bur Oaks shown here drop their leaves six weeks to two months before the purported Q. trojana shown here. The timing of the Mediterranean species is a much better fit with native California deciduous trees, which are evolved to a Mediterranean-typical growing season, with late or no frost. Bur Oak, and other more northerly species, are adapted to early frost, and, in California, typically lose their leaves on warm, summer-like days, thereby missing a great deal of the photosynthetic potential of the climate in which they have been brought.