Many insects, birds, and mammals metabolize tannins with fewer ill-effects than humans. Other animals buffer their acorn diet with other foods. Creatures that cache acorns, such as jays and squirrels, may wait to consume some of these acorns until sufficient groundwater has percolated through them to leach the tannins out. Animals may preferentially select acorns that contain fewer tannins. Since tannins, which are plant polyphenols, interfere with an animal's ability to metabolize protein, creatures must adapt in different ways to utilize the nutritional value that acorns contain. Total food energy in an acorn also varies by oak species, but all compare well with other wild foods and with other nuts.Īcorns also contain bitter tannins, the amount varying with the species. Percentages vary from species to species, but all acorns contain large amounts of protein, carbohydrates, and fats, as well as the minerals calcium, phosphorus, and potassium, and the vitamin niacin. The larvae of some moths and weevils also live in young acorns, consuming the kernels as they develop.Īcorns are attractive to animals because they are large and thus efficiently consumed or cached. (See Native American management of acorn resources.) In North America, acorns were a traditional food of many indigenous peoples. They harvested, peeled, and soaked acorns in natural or artificial ponds for several days to remove tannins, then processed it to make acorn cakes.

In ancient Japan, (Jōmon period), the acorn was an important food. In some human cultures, acorns once constituted a dietary staple, though they are now generally only a very minor food. In Korea, an edible jelly named dotorimuk is made from acorns. In some countries (especially Spain), acorns are used to make a flour for baking (Bender 2005). These may be eaten raw, baked, or roasted, and they also may be ground and used as a coffee substitute (Herbst 2001 Bender 2005). Some varieties of acorns are edible for humans. However, acorns are toxic to some other animals, such as horses. In some of the large oak forests in southwest Europe, traditionally called 'dehesas,' pigs are still turned loose in oak groves in the autumn, to fill and fatten themselves on acorns. Such large mammals as pigs, bears, and deer also consume large amounts of acorns: they may constitute up to 25 percent of the diet of deer in the autumn. Small mammals that feed on acorns include mice, squirrels, and several other rodents. Creatures that make acorns an important part of their diet include birds, such as jays, pigeons, some ducks, and several species of woodpeckers. Acorns take 6 to 24 months (depending on the species) to mature.Īcorns are one of the most important foods for wildlife in areas where oaks occur.

That is, it is a hard, indehiscent (not opening to discharge seeds), simple, dry fruit, whereby the plant's ovary wall becomes very hard (stony or woody) at maturity, and where the seed remains unattached or unfused with the ovary wall.Īcorns vary from one to six centimeters long and 0.8 to four centimeters broad. breviloba) leaves and acornsįrom a botanical sense, the acorn is a true nut.

Acorn tree name