The acorn is a true nut, like the walnut. It is a dry fruit made up of a hard, seamless shell with a single seed within, and a cap of scales that partly and in some cases mostly covers the shell. Among the nine different oak tree and ten oak shrub species of California, acorns vary a great deal. These differences are used to help tell one oak from another. All oaks are of the same family (Fagaceae or beech), and it is the acorn that sets them apart from their relatives. One close relative is an exception, the tanoak. It is not of the same genus as the true oaks, (Quercus) but it still produces an acorn. The tanoak acorn's cap is hairy though, rather than scaly as are all oak acorns.

In fall, depending on the year, acorns are showered upon the ground in numbers that far exceed the numbers that seem to make sense for reproduction of the parent oak tree. These numbers do make sense though, when you consider the difficult time an oak has making it past a critical threshold in its first year as it grows from seed to seedling to sapling.

In addition to a tiny root and a shoot that will form into a stem and leaf, an acorn contains two relatively large "cotyledons", a rich source of food for the plant to use until it has leaves that can then make food. These cotyledons are full of a nutritious blend of carbohydrates, fats, and proteins. They are an excellent food source and for this reason the acorn is among the most sought after fruits in the native landscape.

Of the many hundreds of acorns an oak might produce in a good year, most are consumed by birds, insects and mammals. At least 30 species of birds and 37 species of mammals eat them. As much as half of an acorn crop may contain insect larvae, and several reptiles and amphibians make their living off of animals associated with acorns. Some mammals especially depend on the acorn's rich nut meat to gain reserves they need to make it through the winter, and some even to be successful at reproduction the next year. In the trade that nature often makes though, birds and mammals transport acorns well beyond the tree, and in the process some get dropped, lost and left buried where the chances for an acorn's survival are greater. For example, acorn woodpeckers form an extended family unit that claim a few trees and carefully tend "granaries", a storage area for acorns, typically a dead tree drilled with thousands of holes. In acorn season all these holes may filled. They move the acorns from larger to smaller holes as the acorns dry and shrink. In the process they are able to keep some acorns preserved through to the next summer. Other animals bury acorns, including those stolen from the woodpeckers, and these in particular are helpful to propagate new trees.

Acorns have also been part of the human diet here for thousands of years. The abundance of Native Americans in California, almost a third of all the people living north of the Rio Grande for many centuries, is largely due to the acorn. Once the acorn became part of the diet here, it created an agricultural base that supported numbers of people far beyond what the game animals and other foods had been able to support. Breck Parkman, District Archeologist for State Parks in our region feels that for people in our area in particular, life was very good, to a large degree because of the acorn and its abundance along with other foods here. Acorn mash was a part of almost every meal and dry acorn bread was also frequently consumed and could last for a long time. John Muir felt acorn bread was the most compact and strength giving food available, and no doubt used it as such in his explorations of California. It is still an important ceremonial food for many of the native groups in California.

Whether someday as a pasta, or a natural sports food, or more likely because it ties so much together in our diverse valley and state, acorns are a very important feature of our lives here, and something we should relish.