Wednesday, January 16, 2013

Quercus lobata- Manna of California



On our way back north through the Central Valley, I kept my eye out for Valley Oak (Quercus lobata) and was lucky enough to find a few trees only a short distance from the highway near Cottonwood California.

This fine grove has been pruned of their lower limbs
Valley Oaks are the largest of our North American Oaks often reaching 100 feet tall and more than 5 feet in diameter. Open-grown trees have widely spreading, gnarled branches and rounded crowns, giving the tree a silhouette that is often wider than it is tall. The branches on older trees have a noticeable drooping quality near the tips. The bark is light to dark grey with long braided fissures (more widely spaced than those on Blue Oak bark) that break up into a smaller mud crack or alligator skin pattern (like Garry Oak bark) in large specimens. Leaves are deciduous and are typically 2 to 4 inches long with deep rounded lobes. Both surfaces are densely covered with soft fuzz; the top is green and the bottom is much paler. Their range is limited to the Central Valley and Coastal California below about 2000 feet in elevation where they thrive in deep alluvial soil in places with access to year round moisture.

A few remaining leaves in early winter
Acorns typically arise singly but occasionally grow in pairs, and are 1.5-2.5 inches long and ½-1 inch wide, making them among the largest acorns in North America. Caps are warty and cover the top ¼ inch of the acorn. The cap scar is typically ¼ inch wide, from which point the acorn tapers out abruptly, reaching its widest point in the upper ¼-⅓ of the acorn, and then tapering gradually to a long point. The acorns lack symmetry on a longitudinal axis. Those acorns which are not consumed will sprout during winter rainstorms. Shells are thin and crack the length of the acorn as the hypogeal growth pushes through the shell and roots deeply into the ground, and it is not unusual to find a few acorns shells that have pealed completely off of the nutmeat. Valley Oak acorn nutmeat is a light buttery yellow color with a surface that is frequently stained pink, red, or purple where it has been exposed to the air. The nutmeat around the sprouting tip may also be stained green or brown.

Moderately sized Valley Oak acorns (scale in cm)

Valley Oak acorns are a traditional food used extensively by California Native Americans. The large acorns are collected in the fall and stored for use throughout the rest of the year to make bread, soup, and mush. As with all acorns, the tannins must be leached from the nuts before they can be eaten and the California Native Americans did this by grinding them into flour using a mortar and pestle, and then leaching them with cold water.

Victor Chestnut (1902) documented the traditional use of Acorns by the Native Americans living in the Mendocino County area. He observed that Valley Oaks were among the most prized of the many acorn-bearing species in the area, due to the high fat content, large  acorns, and the shared preference by both human and nut to grow deep roots in the fertile valley bottoms.

Chestnut alluded (pg 334) to the use of leaching pits in which whole acorns are buried in a sandy place with grass, charcoal, and ashes, and then flushed with water from time to time to remove the bitter tannins from the acorns. However, most of his account detailed the process of pounding the acorns into a very fine flower, spreading the flour on a bowl-shaped bed of compacted sand, and gently deluging the reservoir with water, which upon percolating through the acorn flour over the course of a few hours, removes the tannins.

A Hupa woman leaching acorns by a similar method. Photo from Goddard 1903, plate 15.

Evidently, any sand that may mix with the acorn flour is not an issue when the flour is used to make soup, as the heavy sand settles to the bottom of the cooking basket where it can be avoided. When bread is being made, a layer of leaves or more recently, cloth, is sometimes spread over the sand before the flour is laid out. Acorn bread is made by mixing in roughly 5 percent clay by mass. With moderate success, Chestnuts investigated the effect of iron oxide rich clay on the remaining tannin in the bread, and also suggested that the clay absorbs oils that would otherwise be lost, gives the bread an agreeable color, and adds beneficial minerals to the diet.

Terminology related to Valley Oak acorns
Pä’·önsh (Yuki): Bread made from Valley Oak
Sē-pä’ (Litle Lake): Valley Oak acorn
Skin’chön (Wailaki): Valley Oak acorn
Kī-yäm’ (Yuki): Valley Oak acorn
Lō-ē’ (Concow): Valley Oak acorn

Acorns comprised a large part of the traditional diet of California Native Americans. Chestnut observed that a single family would collect about 500 lbs of acorns for the year. In 1986, DA Bainbridge reported that a single Valley Oak trees is capable of producing as much as 2,000 lbs of acorns in a year (see “Use of Acorns for Food in California: Past, Present, and Future”).


In less than five minutes I was able to collect about a quart of moderately sized Valley Oak acorns to use for my own culinary experiments. Back home they are now drying on a large baking sheet in my small apartment. They constantly remind me of the life-sustaining promise that has been endowed upon the many landscapes throughout the Pacific Northwest. Not only is each nut edible, but each holds the potential to produce hundreds of tons of food.

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4 comments:

  1. I am really enjoying reading about your trip. Thanks for sharing. -Corina

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  2. I think we had a beautiful grove growing at the Herb Pharm's Farmstead in Southern Oregon. They were huge, tall like your picture, and I seem to remember the long acorns. would have needed to have been planted there or could the range extend into Oregon?

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  3. The native range of Valley Oak doesn't extend into Oregon, but it certainly is possible that it was planted at Herb Pharm.

    The large oaks that are native to the Southern Oregon include Garry Oak (Quercus garryana), Black Oak (Quercus kelloggii), Canyon Live Oak(Quercus chrysolepis), and Oracle Oak (Quercus morehus). Of these, only Canyon Live Oak (and perhaps rarely Oracle Oak) has elongated acorns.

    The most likely candidate is English Oak (Quercus robur) which grows very tall, and usually has elongated acorns. English Oak is commonly planted as an ornamental.

    Ha! I just did an internet search for "Herb Pharm Oak" and I see that they sell "White Oak (Quercus alba)" extract. They show a picture of their oak, and it is clearly not Quercus alba, but rather Quercus robur (English Oak). You can tell because it has stalked acorns and leaves with small "mouse ear" lobes at the base. Mystery solved! Somebody should tell them that they are mislabeling their product (or representing it with the wrong photograph). It wouldn't be so bad if they only labeled it "white oak," because English Oak is in the white oak group, but they include the scientific name Quercus alba, which is incorrect.

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