Howdy, Park goers! Welcome to the Tree of the Month series by Forestry Supervisor, Joseph Hart. Each month, our forestry team will spotlight a different species from Tower Grove Park’s arboretum.

For September’s feature, we’re highlighting one of Missouri’s forest giants—the Black Walnut (Juglans nigra).

Native to Missouri and much of eastern North America, the black walnut thrives in rich woodlands, stream valleys, and open upland woods. Known for its impressive size, this tree can reach 75–100 feet tall with a wide-spreading canopy. Its pinnately compound leaves—ranging from 13–23 leaflets—emerge late in spring and drop early in fall, turning a pleasant yellow before dormancy. When crushed, the leaves release a strong, distinctive aroma.

🌰 Why It’s Special

Nuts: Black walnuts are prized for their rich, robust flavor—popular in baked goods, confections, and even specialty beers brewed right here in Missouri.
Timber: Highly valued for strength, beauty, and workability, black walnut wood is one of the most sought-after in woodworking.
Dyes: Historically, the nuts, husks, and bark were used to create a deep brown dye.

Additionally, black walnut is known to produce allelopathic chemicals called juglones, which can be very toxic to certain other plants, including azaleas, rhododendrons, peonies, and solanaceous crops like tomatoes, peppers, and potatoes.

Next time you’re exploring Tower Grove Park, keep an eye out—black walnut trees can be found throughout our arboretum, often showcasing striking shapes and silhouettes.

Be sure to check it out on our interactive map using the ‘Tree Walk’ feature!

Visit Interactive Map