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Pen in Hand: Interior Live Oaks: The umbrella trees of the inland ranges
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Posted by editor Mon Jan 21, 2008 10:18:56 PST
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0 responses 1 comment Drive up to Tehachapi on Woodford-Tehachapi Road, the back road from Keene, and here and there you’ll see compact, well-shaped oak trees with dense canopies of deep green leaves. Resembling giant broccoli florets, these handsome oak trees are the seldom-discussed Interior Live Oaks (Quercus wislizenii).

One of the least known of Tehachapi’s oak tree species, Quercus wislizenii is also one of the most interesting and distinctive. Its common name is both appropriate and descriptive because these oaks tend to grow in the interior ranges of California, away from coastal areas that are occupied by the Coast Live Oak (Quercus agrifolia).

The term “live oak” refers to the fact that these trees are evergreen. Most people associate this quality with conifers, such as pines, firs, junipers and cedars, which shed their foliage (needles or scales) gradually over time, so they are literally “ever-green” or always foliated and never bare like deciduous trees, which lose their leaves all at once.

So Interior Live Oaks keep most of their leaves year-round, slowly shedding and replacing them while keeping most of the canopy intact. The leaves get paler and slightly yellowed this time of year with reduced sunlight and hard frosts, but longer days and warmer temperatures in spring will bring forth new chlorophyll and a rush of green to the leaves.

Typical of California’s live oaks, the leaves themselves show a wide diversity: they can be elongated and pointed, or wider and oblong, have either smooth margins or be toothed with spines or bristles — all on the same branch of a single tree.

Because they are subject to year-round browsing pressure from deer and non-natives like cattle, Interior Live Oaks build up concentrations of lignins and tannin to make their flat leaves leathery and less palatable to herbivores.

Though its wood is dense and hard, the Interior Live Oak has never really been logged for one simple reason: it tends to have many smaller trunks that branch almost at ground level instead of having one main straight trunk that could be milled into lumber.

This hasn’t protected Interior Live Oaks from removal, however, because historically they liked to grow along streams and rivers that flowed from the western slopes of the Sierra Nevada down into the San Joaquin and Sacramento Valleys.
 These fertile floodplains also attracted farmers who converted the riparian forests and woodlands into fields of cultivated crops.

Ranching has been much easier on Interior Live Oaks, and some of the best remaining stands of these hardy, picturesque trees occur on private ranchland where cattle shelter from the heat of long dry summers in the deep shade of Quercus wislizenii trees, which were named for a 19th century German botanist with the awkward name of Dr. F. A. Wislizenius.

The acorns produced by Interior Live Oaks resemble those of Black Oaks (Quercus kelloggii), to which they are related. The narrow, tapering acorns are faintly striped and nestled deep in their cups, which have overlapping scales like a shingled roof rather than being knobby and bumpy like the cups of Valley Oaks (Quercus lobata) or Canyon Oaks (Quercus chrysolepsis).

Being able to distinguish between the half dozen different species of tree oaks found in the Tehachapi Mountains simply enhances one’s enjoyment and appreciation of our surroundings. A walk, horseback ride or a drive is more interesting when the trees become like friends or neighbors whose characteristics and quirks are well-known to you.

Interior Live Oaks may not be as familiar as some of California’s other oak species, but they deserve to be, for they are remarkably tough and develop unique canopy shapes that are often as broad as they are tall. Fortunately, we have them in the Tehachapi area.

Have a good week.

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Comment From: tonyorbit

I look forward to learning something new and interesting about our beautiful Tehachapi area from Jon each week. Keep them coming!