Found in all temperate parts of the world, the oak tree has a history with humankind. Many old oaks, especially in the Old World, grew to impressive size, well-deserving of the term mighty. It was revered in the ancient British Isles as a sacred tree and was worshipped by the Druids. It has long been prized as a food source by indigenous peoples of North America for its acorns, which were ground into meal and used, after soaking to remove tannins, to make mush or bread, to thicken stews or to brew into a drink. Early settlers in this country used its fine hardwood to make furniture and other household items.
Here, in the Mogollon Highlands of central Arizona, the oak is not so large, but its importance is undiminished. Although acorns are no longer used as a primary food source by Native Americans, they remain an important food source for wildlife. Bears, squirrels, jays, and Acorn Woodpeckers all depend on acorns for their winter food supply. The bears feast on acorns, among other foods, to provide a layer of fat to help them through their winter hibernation. Jays and squirrels bury acorn stashes in the ground to eat later. So many are cached that a lot of acorns are forgotten or not needed, so they are left where they were buried, and as a result, a new oak tree sprouts. 2020 has been a very poor acorn crop year, due to the lack of monsoon rain.
The Central Highlands is home to four species of oak trees: the gambel oak (Quercus gambelii) (image left) which is deciduous, the Emory oak (Quercus emoryi), the Arizona white oak (Quericus arizonica) and the scrub oak (Quercus turbinella), which are all evergreen, losing their old leaves and growing new leaves at roughly the same time in early Spring. All our oak trees are diecious, though male
and female flowers mature at different times, and all are pollinated by wind. Their flowers are very tiny, best seen with a hand lens. These oaks hybridize readily, so it may be difficult to identify which species you may be observing. The gambel oak is the most easily recognized by its large, lobed leaves, brownish bark and growth patterns, usually growing in clumps. The scrub oak also may grow as a shrub or smallish tree. Both the Emory and Arizona white oaks grow into quite tall trees with grey bark.
Oak trees are subject to the parasitic oak mistletoe (Phorodendron serotinum), which is more accurately described as a hemiparasite. It has its own leaves, so it photosynthesizes, but obtains water, minerals, and some nutrients from its oak host. The oak mistletoe generally does not kill the host tree, but does, in its turn, provide berries as food for some species of birds, and small mammals.
Oak trees are still valued by humans for their wood, shade and beauty, but are needed by our animal, bird, and insect neighbors for food and shelter. Another example of interdependence. Another reason to appreciate the mighty oak.
Contributed by HCNH Naturalist Sandy Stoecker