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Oak Initiative


An Oak is a tree or shrub in the genus Quercus of the Beech family. There are approximately 500 extant species of Oak found throughout the world.

This grove was planted in 2023 to introduce native and non-native Oaks to Yellowstone County. It was planted in coordination with the Montana Department of Natural Resources and Conservation, ZooMontana, Yellowstone Arboretum and the Global Conservation Consortium for Oak. Many of the trees will be observed for yearly growth and seasonal change and reported to a national database to monitor for climate change.

Keystone Species

The Oak is a "Keystone Species" which in definition is an organism that helps define an entire ecosystem. Without its keystone species our ecosystem would be dramatically different or even cease to exist.

Up to 2300 other species are known to be associated with the Oak tree including birds, fungi, invertebrates and mammals. Here in Montana it's important to plant oak trees so we can increase the Oak population and create a healthy ecosystem for all species that call Yellowstone County home !


Oaks in Montana

Only one species of Oak is considered native to Montana. Bur Oak, Quercus macrocarpa, is found in extreme southeastern Montana. It is known as the "Alzada Oak". The largest stand of Bur Oaks here in the arboretum can be found on the hill opposite the amphitheater.

Over the decades the arboretum has planted many other Oaks not native to Montana including the Swamp White Oak, Gambel Oak, Scrub Oak and Mongolian Oak. These species have survived because they originate in climates somewhat similar to ours and enjoy ZooMontana's unique microclimate and protection from the other trees.

Some Interesting Facts

* All species of Oaks are just divided into two groups, White Oaks and Red Oaks.

* Oaks can live up to 1,000 years.

* The fruit of an Oak is the acorn. An Oak tree must be 20-30 years old before it produces acorns.


* Every 2-5 years acorns from Oak trees will all fall at the same time. This is called a "mast". Scientists are uncertain why this happens. 

* Not all Oak leaves are the same. Take a close look at these trees and see the many different shapes.

* Depending on the species, some oaks can grow up to 100 feet tall.

A Symbol of Strength

Hosted by the Arbor Day Foundation, the Oak was voted as our national tree in 2004 and for very good reason, they form the most important and abundant group of hardwood trees in North America. Oak trees are very symbolic of the United States. They represent longevity, stability, endurance, fertility, power, justice and honesty.


The oak tree is considered a medicine tree by many Native American peoples. It is associated with strength and protection. 

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