Acorns

Acorns

Acorns are all around us.  We see them on oak trees, on the ground, and on driveways and sidewalks.  You may have even noticed more acorns in Texas in 2023.  If you’ve wanted to learn more about acorns, read on.

What are Acorns?

Acorns are nuts.  They are like hazelnuts, pecans, chestnuts, and others.  They are fruit of oak trees, and contain a seed that, if planted under the right conditions, can grow into a new oak tree.

What do Acorns Look Like?

Acorns have a seed (sometimes two) that is surrounded by a shell.  They are generally around 0.4 to 2.4 inches long and 0.3 to 1.6 inches thick.  They have a cap called a cupule and a stem.  Acorns generally grow in clusters of two to five.

Although the acorns of different oak species have the same general overall appearance, they also have differences that can help to distinguish which species of oak tree they came from.

For example, acorns from white oaks have a cap that is smaller than that of other types of acorns.  Acorns from chestnut oaks have caps that are bumpy and that cover around half the acorn.  Acorns of post oaks are larger than most and have a flat cap.

Are Acorns a Food Source for Wildlife?

Acorns are a food source for many types of wildlife.  We’ve mentioned before that acorns are an important food for jays.  They are also important for bears, squirrels, other birds, deer, and other animals.

Although many animals eat acorns, acorns have something in them called tannins.  Tannins give acorns a bitter taste and can cause problems if consumed by certain animals or in large quantities by them or others.  In some cases, when animals store acorns in the ground (cache them), groundwater can leach some of the tannins out of them.  In other cases, certain animals can process the tannins differently than others such that they have less of an effect on them.

How are Acorns Dispersed?

Acorns are generally too heavy to be dispersed by the wind.  Instead, animals such as birds and squirrels disperse acorns.  Animals disperse acorns when they move them from one place to another without eating them, or when they cache them and don’t consume them later.  When an animal buries an acorn and doesn’t eat it, it basically has planted the acorn, and that can be the start of a new oak tree.

What is Masting and What Does it Have to Do with Acorns?

Masting is when trees produce a large amount of fruit (or nuts) at one time.  You may have seen this in Texas in 2023 when oak trees produced a large amount of acorns.  The reason for masting isn’t fully understood, but in Texas, oak trees mast every twenty four to sixty months.

Generally, oak trees don’t produce the same amount of acorns each year.  In some years, they produce relatively few, and in other years they produce a lot.  The years when they produce a lot, are the years when they mast.

One effect of masting has to do with animals that eat acorns.  The general idea is that when oak trees mast, they produce more nuts than the animals around them can eat.  This can help ensure that at least some of the acorns survive to germinate into new oak trees.  The cycle of masting is thought to have an effect on animal populations.  In years with light acorn production, animals that consume acorns might decrease in numbers.  As a result of mast years, animal populations might increase.  Part of the idea is that since a decrease in population could occur before a mast year, there could be fewer animals to eat the acorns in the mast year (though their number could increase after it because of the increased food supply) and this could have the effect of having less of the acorns being eaten and could increase the chances that some acorns will survive to produce new oak trees.

You can learn more about masting in a recent radio interview.

When do Oak Trees Start Producing Acorns?

Oak trees start producing acorns after about twenty years.  They can produce acorns in larger numbers until they are around eighty years old, producing the most acorns between fifty and eighty years of age.

Acorns take between a half a year to two years to reach maturity, though acorn crops can fail due to things like drought, freezes, or high temperatures.  Acorns that are ready in the fall (which they generally are in Texas), are the result of flowers that bloomed the previous spring and there can be many things that affect them.

If you liked learning about acorns, check out our other posts on our TrueTreeTalk blog.  We have posts about a number of different topics you might be interested in.  To keep up with our posts, follow us on Facebook, and be sure to tell your friends about us.