By Sarah Dutton

Oct 9 2020

Oak trees are a familiar sight to people all around the world, but you might be surprised at how different their leaves can be!

There are hundreds of species of oaks (genus Quercus). They are native across the northern hemisphere and even as far south as Indonesia. Oaks can be shrubs or trees, and occupy habitats as varied as temperate forests, tropical forests, alpine zones, swamps, deserts and savannahs. Some oaks are called “live oaks” because they are evergreen, many oaks are resistant to fire, and most can live for hundreds of years. In fact, oak trees usually grow for at least 20 years before producing acorns. The highest concentrations of oak species diversity occur in Central America and Southeast Asia, and oak trees have been used by indigenous peoples around the world for thousands of years. For example, oaks are an important source of wood, food, and medicine for many Native American tribes. Because many oaks are resistant to fire, some Native American tribes manage oak forests to suit their needs using controlled burning.

Oak leaves really put Quercus diversity on display. One reason for this diversity is that different Quercus species can hybridize with each other, resulting in highly variable offspring. Leaf sizes and shapes can give plants advantages under different environmental conditions. For example, broad leaves can collect more light in dim conditions, and narrow leaves help prevent water loss.

Please enjoy this brief tour of oak leaves from the herbarium.