The Largest Acorn Ever Found

Written by Hannah Ward
Updated: January 23, 2023
© Kasabutskaya Nataliya/
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Acorns are the nuts from oak trees, and they contain one (or occasionally two) seeds from which new oak trees grow. There are around 500 species of oak trees in the world. They are native to the Northern Hemisphere, with North America having the greatest number of species. Although the saying goes that from a little acorn the mighty oak grows, in some cases, the acorns are not particularly small. In fact, some can be pretty huge!  So join us as we discover the largest acorn ever found!

About Acorns

Acorns are produced by oak trees which are some of the largest and most stately trees in the world. Every year these massive trees produce vast quantities of acorns which can vary in size from less than one inch wide to around 4 inches, depending on the species of the tree.

Oak trees are from the genus Quercus in the Fagaceae family group, which is known as the beech family. They are divided into two groups – red oaks and white oaks. The main differences between the two are the leaf shape and the size. Red oaks are smaller and reach a maximum of 70 feet tall, and have a more pointed leaf shape. White oaks are much taller – regularly above 80 feet – and have a more rounded leaf shape. The acorns also differ between the two. Acorns from white oak trees develop much quicker than those of red oaks, with white oak acorns taking only around three months to develop.  The acorns from red oak trees take up to two years to develop and remain on the trees even when the leaves have been shed.

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Acorns develop in a cup-like structure which is known as a cupule. Cupules protect the fruit of trees in the beech family. In the case of acorns, they protect and hold them as they are developing on the tree. Although cupules often encase the entire fruit on other trees, in the case of oak trees, they do not.  Instead, the cupule only encases half of the acorn. The cupule is usually covered in scales which sometimes develop into spines. These spines are to protect it from predators such as squirrels. However, not all oak trees have cupules with sharp spines.

The Largest Acorn ever Found

The largest acorn ever found belongs to the Chicalaba oak tree
The largest acorn ever found was up to 3 inches long with a 4-inch diameter!

©Kasabutskaya Nataliya/

The largest acorn ever found is the acorns from the Quercus insignis tree – also known as the Chicalaba oak. This tree produces acorns that have a diameter of up to 4 inches and a length of between 1 and 3 inches. They are the largest acorns in the world and are a large and distinctive shape. Quercus insignis acorns are produced in a cup that wraps around the acorn and is covered with thick scales which tend to give them a bur-like appearance.

Of the tree which produces these massive acorns, Quercus insignis is a deciduous species of the white oak tree that is native to Costa Rica, Guatemala, Honduras, and Mexico. They are typically found in cloud forests at elevations between 1,640 and 6,500 feet. They are classed as endangered across much of their range, but particularly in Mexico. This is because they are threatened due to forest clearance for the growing of coffee crops. Quercus insignis are incredibly large trees and can reach a staggering 98 feet tall. Their leaves are up to 6 inches long and 3 inches wide with an elliptical shape and a leathery texture.

Why are Acorns Important?

squirrel eating acorns
Acorns make up a large part of the diet of squirrels, deer, and birds.


Acorns are incredibly important for many reasons. The obvious reason they are important is for the continued health of oak trees as a species through the growth of new needs.  However, they are also important to the health of species that live in and around forests. This is because many animals rely on acorns as they make up a large part of their diet. In fact, the quality of the acorn crop every year can be the deciding factor in whether some animals thrive or whether they struggle to survive the winter. This, in turn then impacts the animals which prey on those that rely on acorns for survival.

Acorns are rich in nutrients and contain a lot of protein, fat, and carbohydrate, which makes them a suitable foodstuff for many animals. Animals such as deer eat particularly large quantities of acorns. Acorns make up around 25% of the diet of deer during the fall and winter months, and white-tailed deer especially love acorns so much that they are one of their preferred food sources! They’re also important to animals such as bears and even pigs. In some countries, pigs are turned out in oak groves specifically so that they can feed on the acorns.

Acorns are also important to many smaller animals too. Many different species of birds rely on acorns – such as woodpeckers, jays, and pigeons. Many different rodents also rely on acorns. Squirrels especially rely on them as they often store them for the harsh winter months when food is scarce.

Problems with Acorns

Although acorns are incredibly important to a lot of different animals, they have their problems too. This is because acorns contain tannins. Tannins are plant polyphenols, and they make it difficult for animals to metabolize protein. These tannins also make acorns toxic to some animals – such as horses and cattle – when consumed in large quantities.

Not all acorns are equal though, as different acorn species contain different amounts of tannins. The acorns from white oaks – including Quercus insignis – contain fewer tannins than those of red oaks and English oaks. Many animals are inherently able to detect which acorns contain less tannins though. This often leads to them naturally selecting acorns of the white oak variety.

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The Featured Image

Background with autumn acorns and leaves closeup. Acorns macro. Acorns on the bark of a tree covered with moss.
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About the Author

I have been writing professionally for several years with a focus on animals and wildlife. I love spending time in the outdoors and when not writing I can be found on the farm surrounded by horses, dogs, sheep, and pigs.

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