White Oaks
The White Oaks
When you're identifying oak trees, consider as many characteristics as possible, from leaves to location.
More than 30 percent of Missouri's land is forested, and oaks are among out most important and abundant trees. Oaks provide food for wild animals in the form of acorns, especially for deer, wild turkeys and squirrels. Oaks belong to the so-called hardwood trees, in contrast to the conebearing needle trees, and are a most important source for lumber. The lumber we cut from oak trees is important to Missouri's economy; it is used for making barrels, furniture, cabinets and flooring.
Oaks also shape the landscape of much of Missouri, provide shade to homes and streets and serve as historical markers.
The oaks form a large group (genus) of worldwide distribution. Most are trees but some are shrubs. One estimate calls for 450 species in the world; another, more modest, calls for 275. In North America, north of Mexico, there are about 54 species, of which 21 are growing wild in Missouri.
This abundance of American oak species compares with just three to five in all of Europe. When the glaciers covered much of the northern hemisphere during the last 2 million years, our oak species found favorable conditions further south; they were trapped by mountain ranges lying east to west, blocking their growth to the south.
Problems of Identification
To begin with, oaks hybridize readily. While one speaks commonly of "hybrid sterility," our oaks have viable hybrids—hybrids with seeds that produce trees.
The amazing variability in the leaf shapes of certain species is confusing. This forces us to accept certain basic leaf shapes for identification, though we know full well that differing shapes are common.
The leaves of young trees often vary totally from the mature shape. They can be huge, an assist by nature to form an enlarged chlorophyll factory, but not conducive to identification.
No wonder Julian Steyermark, author of Flora of Missouri, said that in identifying oaks, it must be kept in mind that as many characteristics as possible—leaves, twigs, winter buds, range, bark, site—must be taken into consideration.
Oak Characteristics
Oaks have separate male and female flowers on the same tree. Male flowers are pollen-bearing stamens on catkins; females are rounded-to-pointed, knob-like and usually on short spikes in leaf axils. Pollination is by wind, requiring huge amounts of pollen.
The fruit, the acorn, takes one or two years to reach maturity. The combined fruits of oaks, hickories, walnuts and beeches form the "mast" of life, sustaining deer, raccoon, squirrels, chipmunks,'possum, mice and fox. Turkey and quail also eat acorns, as do waterfowl.
Acorns are attacked by a host of insects; because of that, only an occasional one will produce a new tree. Most oaks take more than 30 years before they produce acorns.
The following is an attempt to provide useful information for identifying native oaks. In no way is this a botanical text, which would have to cover a much greater area in much more detail. The native oaks are presented in two groups, the white oaks and the red oaks.
White Oaks–General Characteristics
- They produce the most valuable oak lumber, because the cells contain bubblelike structures–tyloses–making the heavy wood leakproof.
- Their acorns mature during one year.
- The cups of their acorns contain no hair inside.
- Their leaves are lobed or serrated (saw toothed without bristles).
- They produce "sweet mast," having less tannin than the red oaks.
