| California Black Oak |
| I’ve decided this winter to start tackling oak trees… Tackling, you say? Well, I can identify an oak tree as an oak tree, but what species of oak is it? We have several species in our area and I don’t really know how to tell the difference between them all. So I’ve decided to study up. First things first - what makes an oak tree an oak tree? Oak trees are in the family Fagaceae which is derived from the Latin word Fagus which means, “to eat.” Trees in the family Fagaceae indeed have edible fruits called acorns. They are also monoecious trees which means you can find both male and female flowers on the same tree. The flowers are small and inconspicuous because they have no petals. The male flowers have between 4 and 40 stamens and are usually grouped in clusters called catkins. The female flowers have a single pistil and are surrounded by a bract which becomes the acorn at full maturity. The female flowers can be solitary or in small clusters often near the base of the male flowers. The leaves are simple and pinnately veined with margins that are often lobed. Leaves drop in the fall, thus the tree is deciduous. Oak trees are in the genus Quercus, which is a Latin word that is thought to have been derived from the Celtic quer “fine” and cuez “tree.” The oak tree I decided to learn about first is Quercus kelloggii, or the California Black Oak. John Newberry named this oak tree in 1857 in honor of Albert Kellogg, a pioneer California botanist and physician. They have a very dark-colored blackish bark, hence their common name. I decided to start with the California Black Oak because there are more of them and they grow over a wider range in California than any other oak species. California Black Oaks grow from west-central Oregon south to Baja, California. They are common in the coastal ranges and the western foothills of the Sierra Nevada. They grow where the summers are hot and dry but the winters are cool and moist. Here in the southern Sierra Nevada they grow from about 4,000’ to 7,800’ in elevation amongst Ponderosa Pine, Incense Cedar, White Fir, and Giant Sequoia Trees. California Black Oaks attain their largest size in the Sierra Nevada. They can get up to about 130’ in height and 5 feet in diameter. They can also live to be about 500 years old! Most California Black Oaks get their start not by seed but by sprouting from fire damaged or cut parent stumps. The reasons for this are many. These oak trees typically don’t produce many acorns until they are at least 80-100 years old. Then, for unknown reasons, acorn yields vary from year to year. When acorns are produced, insects destroy many of them in their developmental stage. After they fall they are often damaged by blue-gray mold. If they escape the insects and mold, well then most are eaten by at least 14 species of song and game birds, many small mammals, bears, and mule deer. In the fall acorns are the primary food source for many of these animals. Domestic cattle and sheep and non-native wild pigs eat the acorns as well. If an acorn does survive fall they usually lie dormant underneath leaves on the forest floor in the winter then germinate in the spring when the weather warms. If the seedling gets enough water and survives insect and mold infestation, as well as pocket gophers, it can get up to 6 inches high and send roots down as far as 30 inches in its first growing season. Because acorns have a low rate of germination and seedlings a low rate of survivability, most oak trees in California originate from sprouts. How long they live is determined by a variety of factors. A California Black Oak’s worst enemy is fire. Both ground and crown fires are often fatal. And if a fire doesn’t kill them outright, a fire scar can be the entry point for fungi. The tree is especially susceptible to fungi, including heart rot. So how can you tell apart a California Black Oak from other oaks in this area? You can start with where the tree is growing… Is it growing from 4,000’-7,800’ in elevation? Yes? Then examine the tree. Is it a deciduous tree (does it drop its leaves in the fall?) That would distinguish it from live oaks which keep their leaves year-round. Are the leaves 4-10 inches long and pinnately lobed, usually with 7 lobes? Are the lobes 3-toothed and bristle-tipped? If they’re bristle-tipped, that would distinguish it from White and Blue Oaks whose leaves do not have bristles. Now look for an acorn… Are they from 1 to 2.5 inches long? Are they reddish brown and do the caps cover about half the acorn? In other oak species the caps cover less than ½ the acorn. So, if the tree you’re examining has these features, then you’re looking at a California Black Oak! If you’re exploring a black oak stand that is near a creek you may also take the time to see if you can find mortar holes. Native American families harvested acorns in the summertime and pounded them into meal in mortars they had worn into granite bedrock. This meal was then leached with water in order to remove bitter tannic acid then it was cooked and eaten as soup, mush, bread, or patties. Today, acorns are still gathered by people of many different tribes in California and southern Oregon. Back to Trees Back to Tarol's Homepage |
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