The Cal State Fullerton Arboretum and Botanical Garden has 38 subcollections containing a wide variety of different plants, trees and flowers. One of these is the Thorn Forest, which is located in the area around the Acacia Gate leading to the student residence.

Thorny forests are a collection of plants that grow in subtropical or warm temperate areas with little seasonal rainfall. However, they can change into savanna woodlands as rainfall increases, or deserts in drier climates. Thorny forests are typically found in Africa and Central/South America, although they also occur in other parts of the world.

These plants mostly consist of small, thorny trees and have adapted to shed their leaves during dry periods to prevent water loss. They have a photosynthetic bark and small, leathery leaves. They also have long roots that allow them access to groundwater. Cacti and milkweed are common.

“The trees and shrubs in this collection are well adapted to heat, so they usually look good all summer long,” said Greg Pongetti, curator of living collections. “There are many types of salvia and other perennials planted under the trees, and you can usually find something flowering all summer long.”

Thorny forests are important for several reasons. They can protect endangered plants, attract pollinators, and have culinary and medicinal uses. For example, the silky hairs of the fruit of the white silk tree from western South America are used as stuffing for pillows, mattresses, and upholstery, and repel fleas, bed bugs, and moths. The oil from these seeds can also be used in cooking and to make soap.

Plants in the thorn forest of the Arboretum and Botanical Garden include the espinillo (Vachellia caven), the boat thorn acacia (Vachellia campeachiana) and the anaboom wattle (Faidherbia albida).

Learn more about the Cal State Fullerton Arboretum and Botanical Garden.