1.)I think the topic is pretty rad
2.)It will tell you how to make acorn bread!
3.)I wrote it!
Quercus: A Civilized Tree
The Oak is one of the most common trees in the forests of Southeast Ohio. Twelve species of oak naturally occur locally in our forests. The forests we live in and around are actually defined by the name oak: the oak-hickory climax forest. The oak tree has always played an important role in human societies, providing excellent quality wood for shelter and structural building as well as a major food source for ancient peoples. Its value is somewhat underestimated by modern society. The oak has built bridges, corked wine bottles, erected walls, even let us eat those amazing truffles which have symbiotically grown with the oak. It has connected continents with ships unprecedented in their fortitude. It has won wars and been the very symbol of a forest for many people. The oak even helped Americans’ win the war of 1812 with the British in naval battles that took place right here in Ohio by building an impenetrable fleet of oaken warships. The characteristic most commonly attributed to the oak is strength or fortitude. Indeed, it is one of the oldest and largest species in our forest, but holds no titles in either category. It is seen on street corners and parks as well as in our forests. What has made the oak, or Quercus, (as the latin family name is called and will be called henceforth in this paper) such a symbolic as well as useful tree is its ability to adapt to situations. In no way is Quercus, with its many species, a niche specialist; it is one of the most flexible families of trees and thus able to colonize landscapes and habitats from Bangor, Maine to Mexico City. According to Kevin Nixon, a paleobotanist at Cornell University, this is the greatest testament to the Oak which led to its widespread dominance in North America.
Quercus is such a widespread genera, with over 600 species worldwide, that I cannot discuss the many aspects of the oaks. First, we will explore the common categorization of the oak into two different groups: the red oaks and the white oaks. These two groups can be easily distinguished by the bristles on the leaf margins. The red oaks have these bristles, or points, and the white oaks do not. Another major differentiation between these two groups is that red oak acorns take two years to mature where the white oak group flowers and fruits every year. Red oak acorns generally germinate in the autumn and are larger than white oak acorns, which germinate in the spring. This is also interesting, presenting different niches between genera to avoid competition. The acorns also vary in the amount of tannins they contain.
This difference in oaks may not seem to mean much, but produce resounding effects. Oak trees all produce a nut, known as the acorn. Acorns are a valuable food source for wildlife. Deer, birds, squirrels, mice, bear, and other animals consume acorns. Some animals stash acorns in caches when times get tough and food sources become scarce. Oaks and other trees display a strange behavior called “masting”. A “mast” year is when a tree produces an abnormally large crop, or amount of acorns, flooding the ground with its fruit. Other years, oaks will produce barely any acorns. This is in part a result of environmental cues and genetics. These seed eaters essentially are the “predators” of the oak trees. The masting of oak trees has far-reaching effects. Normal years of fruit production act as a method of predator population control. Smaller yields of acorns and limited food results in a lower population of predators such as White-tailed Deer and Field Mice. However, in masting years the amount of food available increases exponentially for these species and they are able to reproduce and flourish. The population levels of these species are dependent on the oak.
Of course the goal of the oak trees is not to feed a host of animals. The goal is to reproduce. This means of population control allows the oak to inundate the habitat with seeds every few years and produce more seed than can be eaten. This relationship between seedeaters and oak is symbiotic as well. Squirrels consume acorns but also facilitate in seed dispersal by losing track of the caches where they store acorns in the ground. Masting year effects eventually even reach humans, even if we would like to believe we are “above” nature. Mice and deer are known carriers of Lyme disease. An increased number of deer and mice results in an increase in tick populations, which results in an increase of Lyme disease in human populations. Even more interestingly, different species of oak follow different masting patterns. That is, red and white oak usually mast on different years. Amazingly, oaks follow an extremely predictable cycle of masting and non-masting over time. Oaks also display synchronous masting, which means that members of the same species will mast at the same time across a large geographic range. This creates an extremely complex system especially in ecosystems with multiple species of oak.
The oak has imbued its fruit with some defense to predation. The curiously named “acorn” comes from an old English word “æcern” meaning “fruit, berry”. Acorns contain varying amounts of tannins, a chemical that is astringent and acts as a bittering agent that encourages animals not to eat the fruit. Tannins produce a very adverse effect on the absorption of nutrition. Traditionally, tannins have been used to tan leather. In essence, tannins block the villi of the small intestines from absorbing other chemicals such as sugars and carbohydrates. So a diet high in tannins will make nutrient uptake more difficult. Some animals have digestive means to cope with this dilemma; most animals simply eat more acorns to make up for lost nutrition.
Some species depend solely on the oak for survival. One such of these is the Acorn Woodpecker (Melanerpes formicivorus). These birds drill thousands of holes into a “granary” tree, marking their territory. This allows the birds to survive over the winter on bountiful years of acorn production. On masting years, it has been observed that acorn woodpeckers breed in the fall instead of the spring. In poor years of acorn harvesting, these woodpeckers will sometimes abandon their territory altogether and make moves for better territory. When more than two species of oak are present in a woodpecker territory, the birds have been shown to do much better. Squirrels are another species that have formed an interesting relationship with the oak, living in oak trees, consuming oak fruit as well as other nuts, and acting as a seed disperser. Squirrels usually have up to a dozen “caches” where they store nuts over winter and although it has been shown they have a knack for memorizing locations, they usually forget or never get to at least one of their caches.
The amount of time the acorn spends on the oak tree directly affects the amount of tannins it contains. Red oaks contain more tannins than white oaks because tannins have longer to accumulate. Red oak acorns are also typically larger and contain more nutrition, however are considered less important for wildlife than the white oak group. Some white oak acorns can be eaten straight out of the shell as they contain little tannin. Just because red oaks contain more tannin does not necessarily mean that the acorns have a negligent effect on wildlife, both oaks are needed to provide a food source due to the alternate nature of masting years. Some species examples in our area that fall under the “white oak” category are the White Oak(Quercus alba), Chinquapin Oak(Quercus muhlenbergii), and Burr Oak(Quercus macrocarpa). Of the “red oaks” which seem to be more abundant are the Red Oak (Quercus rubra), Black Oak(Quercus velutina), and Scarlet Oak(Quercus coccinea).
Developmentally, an acorn forms from wind pollination between oaks. Oaks sometime hybridize with one another. The branch tips can contain both sexes of flowers, but does not self-fertilize due to timing differences in phenology cycles. The ovary becomes the actual acorn with the petals and sepals becoming the acorn caps. It is unknown how far oak pollen can travel. One of the ways oak acorns are distributed is simply by gravity; that is from falling off a tree and rolling down a hill. Other means of acorn transportation include movement by squirrels and other rodents, woodpeckers and other birds, and humans. Many species of oak have shifted outside their natural ranges due to human landscaping; oak is one of the more popular street and park trees. The Burr Oak is a great example of this, traditionally a northern species. Only two exist in Athens, both planted here for their appealing qualities.
This autumn season was a mast year of unprecedented status. It seems like all the species of oak simultaneously fruited heavily. This is not only very exciting news for squirrel and wildlife but also for humans. Until recently, (the past 150 years) humans depended on acorns as a food source. Many native peoples used acorns as flour or as a coffee substitute. Information gathered from Native American Ethnobotany has shown that over 30 North American tribes used acorns as a food source among many other uses medicinally. Oak was used as a headache suppressor, an intestinal regulator, for cigarette papers, to stimulate birth, eyewash, as an astringent, for dysentery, and as dye. It is good to keep in mind that every plant has some kind of use, but one can easily see what a useful genera Quercus was to native peoples. Even today people still use acorns as a food source, I had heard about it, and decided to give it a try of my own.
A nutritional analysis of acorns shows that acorns might be considered a “super food” by some. Acorns are calorically rich, high in fat and protein, and contain folate, niacin, pantothenic acid, B-vitamins, calcium, iron, magnesium, phosphorus, potassium, zinc, copper, and are especially rich in manganese. All of these are vital and necessary components to a healthy diet, and I was not surprised to learn that acorns contain absolutely no sodium or cholesterol. The only real problem with the acorns is this tannin problem, and unfortunately humans do not have the gastrointestinal tract to handle the astringent effects.
So again, I went to native people for an answer. I had hung out with some of the Shawnee Remnant Band in Bellefontaine west of Columbus. They mentioned acorns as a food source so I began doing some of my own research. I found that traditionally there are many ways to prepare acorns; the one being the easiest was to let the acorns sit in a “rock trap” in a swiftly flowing stream. The constant movement of water leached the tannins out and left the nut perfectly edible. After this the acorns could be de-shelled (either after leaching or prior to) and left to dry and later ground into flour or cooked into soup or stews. The shelf life of the flour was in years, not months. This was a way to feed people with no staple crops, as many of the natives did not have any staples besides amaranth and wild rice to sustain them through the winter months.
With the modern conveniences of technology, modern Do-It-Yourselfers can process acorns from the comfort of their own homes. It makes sense to use acorns of the white oak group considering they have much less tannin and are easier to process. I chose the Chinquapin oak after trying a taste test and realizing it was sweet enough to eat straight out of the shell. I later found that this was one of the favorite acorns of some of the Great Plains Indians of Missouri and Arkansas. The Chinquapin oak only grows in alkaline soils, so it is more or less an anomaly around Southeast Ohio where most of the soil is slightly to seriously acidic. I found all the acorns I needed with four friends at Fox Lake in a matter of hours and filled an entire paper grocery bag, being careful to leave some of this forest favorite for the wildlife. It is important to get ripe acorns, dark in color with no weevil bores in them. With people to help shell the nuts, the effort was easy. A simple tap of the hammer will do the job of cracking the shell which will easily peel exposing a yellow nut that I think gives the Chinquapin its other name of Yellow oak.
After this you have the choice of simmering the tannins out of the shelled nuts or soaking the acorns in water to remove tannin. I chose the latter, which is also a longer process. Once the water turns clear after soaking or boiling, the tannins are no longer present and the acorns are ready to be ground into flour or eaten in whatever form you desire in a tasty, nutty snack. I find the flavor to be similar to corn bread when baked into bread, both sweet and delicious. I think my class enjoyed it by the lack of bread I left the room with.
The last thing I would like to cover in this paper is the effects of parasites and fungi that affect the Quercus genera. I was amazed at the amount of acorn weevil larvae in the acorns I gathered. At least one out of five acorns contained one of these little parasites. Rates of predation as high as ninety percent have been recorded in some species of oak, especially in non-masting years. Two types of acorn weevils parasitize oak trees: short-snouted acorn weevils and long-snouted weevils. Both of these genera feed on the acorn flesh and lay their eggs inside the shell. The long-snouted weevil drill holes through the shell to deposit their eggs. The short-snouted weevil deposits eggs through cracks in shells, affecting only already damaged acorns. The larvae grow inside the acorn until large enough to eat their own way out, burrowing into the ground for at least a year to repeat the cycle.
Acorn moths are another parasite of old acorns. The female lays her eggs inside old acorns, the eggs hatch and produce acorn moth caterpillars which eat the remaining meat of the acorns, grow and metamorphose by cocoon into the acorn moth. The filbert worm is another parasite that attacks acorns when they are young and still attached to the tree. Acorn Gall Wasps are a parasite that lay eggs in the female flower of all species of oak. The gall wasp is one of the oldest parasitizer of oak. The oak builds around the eggs as a defensive measure in essence protecting the wasp eggs until they are ready to hatch. The particular species of oak I worked with, Quercus muhlenbergii has a particular relationship with the Grey Hairstreak, a butterfly that feeds on the nectar of the flowers. The oak will host the larvae, although it is unclear if they feed on the fruit or the leaves. Once the shell of the nut is breached, the nut is easily infiltrated by a number of fungi and other diseases. A few diseases like drippy nut that afflicts the California Live Oak can affect acorns once predated upon.
Such a versatile and successful family such as the Oaks deserve our respect and our protection. I know my family is nowhere near as functional. The story of the Oak is another beautiful example of things working out. It really seems like everyone is a winner: the birds, the mammals, the parasites, the humans, and most importantly the trees. I hope that this paper will inspire people all over the Northern Hemisphere of our planet to find an oak, give it a big hug, and maybe even try an acorn. This familiar tree is here to stay awhile, one of the foundations of our ecological community.
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