Aesculus parviflora aka Bottlebrush Buckeye

Bottlebrush buckeye, Aesculus parviflora, is a deciduous shrub in the soapberry family, Sapindaceae. It grows wild in rich, moist woods and ravines of the southeastern United States. Its core native range covers Georgia, Alabama, South Carolina and northern Florida. Gardeners value it as one of the few shrubs that flower well in summer shade.

This is a broad, mounded shrub with many stems. It spreads by suckers and slowly forms large colonies. Most garden plants reach 8 to 12 feet (2.5 to 3.7 metres) tall. They grow wider than tall, often 8 to 15 feet (2.5 to 4.6 metres) across. Some sources give heights up to 15 or even 20 feet (4.6 to 6 metres). The upright branches carry gray stems with whitish buds, and the bark is smooth and gray.

The leaves sit in opposite pairs and are palmately compound. Each has five to seven toothed leaflets, up to about 8 inches long. They open bronze, turn dark green, and are grayish and slightly hairy beneath. Autumn color ranges from clear yellow to yellow-green. In mid-summer, usually July, upright cylindrical panicles 8 to 12 inches long appear above the foliage. Each holds many small, tubular white flowers. Long stamens with reddish anthers stick out well past the petals and give the bottlebrush look. Bees, butterflies and hummingbirds visit the blooms. Smooth, pear-shaped husks follow, each holding a glossy brown nut with a pale scar. Fruit ripens in autumn but rarely sets in cooler northern gardens with short seasons.

The shrub does best in rich, moist, well-drained soil with plenty of organic matter. Slightly acid soil suits it, though the RHS lists it for chalk, clay, loam and sand. It thrives in part shade and tolerates deep shade. Some sources report it grows and flowers well in full sun too. Young plants dislike drought, but established shrubs cope with brief dry spells. It is slow to establish. It is hardy in USDA zones 4 or 5 to 8 or 9 and rated H5 in the UK.

Use it as a specimen, a shady hedge or screen, or massed in a woodland border. It suits pond and stream banks and helps hold soil on slopes. Deer and rabbits tend to leave it alone. Give it plenty of room, because suckers can spread beyond a small bed. Routine pruning is rarely needed. Heavy pruning can renew an old, overgrown plant.

It suffers fewer pest and disease problems than most buckeyes. The RHS notes possible horse chestnut scale and leaf-mining moth. It also lists coral spot, canker, leaf spot and honey fungus as risks. All parts can harm people and pets if eaten. The nuts contain bitter saponins and are not safe raw. Historically, people roasted and leached the seed before eating it, and crushed seed served as a soap substitute.