In July, one of the most eye-catching plants at The Morton Arboretum is bottlebrush buckeye (Aesculus parviflora), with a cloud of spectacular white blooms up to a foot long, held above a dense, green shrub that may be as large as a compact car.

With rich green leaves that turn a buttery yellow in fall, bottlebrush buckeye is a commanding presence in the woodland understory. Butterflies and other pollinating insects are attracted to the blooms in summer, and in autumn its nuts feed squirrels and other wildlife.

Bottlebrush buckeye has fruits similar to its close relative, the native Ohio buckeye tree (Aesculus glabra). A green pear-shaped husk develops over the summer and splits open in early fall to release a dark brown nut with a light patch that early settlers thought resembled the eye of a deer—hence the name “buckeye.” The nuts are toxic to humans and don’t seem to interest deer.

The “bottlebrush” part of the plant’s common name refers to the shape of the large blooms. Each of them is actually a cluster of many small flowers, earning the plant its scientific name “parviflora,” or “having small flowers.”

Bottlebrush buckeye is native to the southeastern U.S., as far south as northern Florida, but it’s fully hardy in the Chicago area, rated for USDA winter hardiness zones 5 to 8.

It can be a handsome addition to a shady area of a large garden, but it spreads aggressively, so it needs space for a thicket-forming shrub that can grow at least 8 to 12 feet high and wide, with ample elbow room. The planting site should be in part to full shade. In a sunny site, the shrub’s leaves can get scorched.

If pruning is necessary, do it within a few weeks after the shrub flowers. That will avoid removing next year’s flower buds, which form soon after blooming.

At The Morton Arboretum, you can find magnificent examples of bottlebrush buckeye in the Ground Cover Garden (parking lot P-1), along the Meadow Lake Trail (parking lot P-1), in the Buckeye Collection (parking lot P-6), and on the Arboretum’s West Side outside the Thornhill Education Center (parking lot P-21), pictured above. 

Once you learn to recognize this beautiful, expansive shrub, you’ll notice it throughout the Arboretum’s gardens and landscapes. Its large, white blooms are sure to be a delightful part of your summer visit.