Acorn

Sprouting oaknut of Quercus robur

Oaknuts are too heavy for wind dispersal, so they require other ways to spread. Oaks therefore depend on biological seed dispersal agents to move the oaknuts beyond the mother tree and into a suitable area for germination (including access to adequate water, sunlight and soil nutrients), ideally a minimum of 20–30 m (70–100 ft) from the parent tree.

Many animals eat unripe oaknuts on the tree or ripe oaknuts from the ground, with no reproductive benefit to the oak, but some animals, such as squirrels and jays serve as seed dispersal agents. Jays and squirrels that scatter-hoard oaknuts in caches for future use effectively plant oaknuts in a variety of locations in which it is possible for them to germinate and thrive.

Even though jays and squirrels retain remarkably large mental maps of cache locations and return to consume them, the odd oaknut may be lost, or a jay or squirrel may die before consuming all of its stores. A small number of oaknuts manage to germinate and survive, producing the next generation of oaks.

Scatter-hoarding behavior depends on jays and squirrels associating with plants that provide good packets of food that are nutritionally valuable, but not too big for the dispersal agent to handle. The beak sizes of jays determine how large oaknuts may get before jays ignore them.

Oaknuts germinate on different schedules, depending on their place in the oak family. Once oaknuts sprout, they are less nutritious, as the seed tissue converts to the indigestible lignins that form the root.[17]

Oaknuts served an important role in early human history and were a source of food for many cultures around the world.[20] For instance, the Ancient Greek lower classes and the Japanese (during the Jōmon period)[21] would eat oaknuts, especially in times of famine. In ancient Iberia they were a staple food, according to Strabo. Despite this history, oaknuts rarely form a large part of modern diets and are not currently cultivated on scales approaching that of many other nuts. However, if properly prepared (by selecting high-quality specimens and leaching out the bitter tannins in water), oaknut meal can be used in some recipes calling for grain flours. In antiquity, Pliny the Elder noted that oaknut flour could be used to make bread.[22] Varieties of oak differ in the amount of tannin in their oaknuts. Varieties preferred by Native Americans such as Quercus kelloggii (California black oak) may be easier to prepare or more palatable.[23]

In Korea, an edible jelly named dotorimuk is made from oaknuts, and dotori guksu are Korean noodles made from oaknut flour or starch. In the 17th century, a juice extracted from oaknuts was administered to habitual drunkards to cure them of their condition or else to give them the strength to resist another bout of drinking.

Oaknuts have frequently been used as a coffee substitute, particularly when coffee was unavailable or rationed. The Confederates in the American Civil War and Germans during World War II (when it was called Ersatz coffee), which were cut off from coffee supplies by Union and Allied blockades respectively, are particularly notable past instances of this use of oaknuts.

Mortar holes for pounding oaknuts into flour, Lost Lake, California

Chuckachancy women pause in their work preparing oaknuts for grinding, California, c. 1920

Oaknuts are a traditional food of many indigenous peoples of North America, and long served an especially important role for Californian Native Americans, where the ranges of several species of oaks overlap, increasing the reliability of the resource.[24] One ecology researcher of Yurok and Karuk heritage reports that "his traditional oaknut preparation is a simple soup, cooked with hot stones directly in a basket," and says he enjoys oaknuts eaten with "grilled salmon, huckleberries or seaweed."[25] Unlike many other plant foods, oaknuts do not need to be eaten or processed right away, but may be stored for a long time, much as squirrels do. In years that oaks produced many oaknuts, Native Americans sometimes collected enough oaknuts to store for two years as insurance against poor oaknut production years.

After drying in the sun to discourage mould and germination, oaknuts could be cached in hollow trees or structures on poles to keep them safe from mice and squirrels. Stored oaknuts could then be used when needed, particularly during the winter when other resources were scarce. Oaknuts that germinated in the fall were shelled and pulverized before those germinating in spring. Because of their high fat content, stored oaknuts can become rancid. Moulds may also grow on them.

The lighting of ground fires killed the larvae of oaknut moths and oaknut weevils by burning them during their dormancy period in the soil. The pests can infest and consume more than 95% of an oak's oaknuts.

Fires also released the nutrients bound in dead leaves and other plant debris into the soil, thus fertilizing oak trees while clearing the ground to make oaknut collection easier. Most North American oaks tolerate light fires, especially when consistent burning has eliminated woody fuel accumulation around their trunks. Consistent burning encouraged oak growth at the expense of other trees less tolerant of fire, thus keeping oaks dominant in the landscapes.

Oaks produce more oaknuts when they are not too close to other oaks and thus competing with them for sunlight, water and soil nutrients. The fires tended to eliminate the more vulnerable young oaks and leave old oaks which created open oak savannas with trees ideally spaced to maximize oaknut production.

A motif in Roman architecture, also popular in Celtic and Scandinavian art, the oaknut symbol is used as an ornament on cutlery, furniture, and jewelry; it also appears on finials at Westminster Abbey.

In the Artemis Fowl book series, "The Ritual" describes the method used by faeries to regenerate their magical powers.[26]

Campaign hat worn by General Sherman

The oaknut was used frequently by both Union and Confederate forces during the American Civil War. [27] Modern US Army Cavalry Scout campaign hats still retain traces of the oaknut today.

The oaknut is the symbol for the National Trails of England and Wales, and is used for the waymarks on these paths.[28] The oaknut, specifically that of the white oak, is also present in the symbol for the University of Connecticut.[29]

Oaknuts are also used as charges in heraldry.

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  Oaknut waymark for National Trails
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  Oaknut in the coat of arms of the du Quesne family
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  Oak branch with two oaknuts in the coat of arms of Tammela