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Aesculus glabra Willd.
Ohio Buckeye
Federal Protection: No US federal protection
State Protection: No Georgia state protection
Global Rank: G5
State Rank: S2
Element Locations Tracked in Biotics: Yes
SWAP 2015 Species of Greatest Conservation Need (SGCN): Yes
SWAP 2025 Species of Greatest Conservation Need (SGCN): No
2025 SGCN Priority Tier: None
Element Occurrences (EOs) in Georgia: 11
Habitat Summary for element in Georgia: Mesic forests in mafic soil
Deciduous tree up to 60 - 70 feet (18 - 22 m) tall, although usually not exceeding 30 feet (9 m) tall. Bark on the trunk is gray, scaly, and warty; bark on branches and twigs is smooth and gray. The branches curve down then up at the tips. The leaves are opposite with 5 - 7 leaflets and leaf stalks that are 3 - 6 inches (8 - 15 cm) long. Individual leaflets are 2.75 - 6 inches (7 - 15 cm) long and 1.6 - 2 inches (4 - 5 cm) wide and have no (or very short) stalks; they are elliptic to lance-shaped with long-pointed tips and tapering bases, and are mostly hairless and have toothed margins. Flower clusters are 4 - 8 inches (10 - 20 cm) long and held upright at the tips of small branches. Flowers are 0.75 - 1.2 inch (2 - 3 cm) long, with 4 greenish-yellow petals (often with a reddish-orange patch near the base of the upper petal), 7 strongly exserted stamens, and a yellowish-green tubular calyx with 5 rounded lobes. Fruits are light brown, round capsules 1.2 - 2 inches (3 - 5 cm) in diameter, with a spiny, leathery husk. When ripe, the husk splits into three parts to release 1 - 4 shiny, dark brown seeds, each with a lighter colored “eye” patch. The seeds are deadly toxic to humans and other mammals. The leaves and twigs give off a foul, skunky odor when crushed.
In Georgia, Ohio Buckeye grows near Yellow Buckeye trees (Aesculus flava), Red Buckeye (Aesculus pavia, a shrub or small tree), and Painted Buckeye (a shrub, Aesculus sylvatica). In flower, Ohio Buckeye can be distinguished from these by its long, exserted stamens about twice as long as the petals. In fruit, it is the only one of these species to have spiny husks. Throughout the growing season, it can be distinguished by the foul, skunky smell given off by the leaves and twigs when crushed.
Aesculus parviflora (Bottlebrush Buckeye, Georgia Special Concern) occurs in moist bluff and ravine forests in west Georgia from Harris County south to Early County. For more information, see: https://en.wikipedia.org/wiki/Aesculus_parviflora
Moist forests with nutrient-rich soils derived from limestone or mafic bedrock, especially in bottomlands.
Aesculus glabra is a deciduous, shade-tolerant tree with soft, light wood and a moderate growth rate, reaching its maximum height at 60 - 80 years and usually found in the subcanopy. It begins flowering and fruiting at 8 years. Buckeye species (Aesculus spp.) are the earliest trees and shrubs to leaf out in north Georgia and the earliest to drop their leaves, usually in late summer. Flowers emerge each spring soon after the leaves develop but well before the canopy closes. Flowering lasts for 2 - 3 weeks. Within the flower cluster, the lower flowers are perfect, i.e. have both female and male parts, while the uppermost flowers are usually staminate (male). Only the former produce fruits and, in any particular flower cluster, only a few flowers will produce fruits. The flowers are pollinated by Ruby-throated Hummingbirds and various long-tongued bees. Bees collect both nectar and pollen from the flowers. Because they are toxic, the seeds are rarely eaten by animals and are primarily dispersed by gravity and water. The seeds overwinter on the ground and begin germination in the spring, quickly producing a strong taproot in the first year.
Aesculus glabra interacts in a number of ways with other plants in plant communities where it is a dominant species. Its early leaf-out reduces light availability and soil temperatures on the forest floor and hence the number and density of spring ephemeral species. Its leaves have a higher phosphorus content than 98% of the other trees in the northeastern US, which raises soil phosphorus levels. Its early leaf-fall reduces the amount of water removed from the soil in late summer and fall.
Aesculus glabra may be identified year-round by its opposite branching pattern and by crushing a twig, which will release a fetid smell. Flowers and fruits available in spring and summer will also provide definite identification.
Throughout most of central and eastern North America, reaching its southernmost extent in south-central Alabama. In Georgia, Ohio Buckeye is known mostly from the northwest corner of the state in the Appalachian Plateau and Ridge & Valley ecoregions.
Logging, conversion of habitat to pine plantations and residential and commercial developments, impoundment of small streams, and limerock mining.
Aesculus glabra is ranked S2 by the Georgia Department of Natural Resources, indicating that it is imperiled in Georgia. Ohio Buckeye has been observed in nine locations in Georgia, but only four of these observations have been confirmed since 1995. Two of these populations occur on state Wildlife Management Areas, and two occur on private lands.
Georgia’s Aesculus glabra plants are on the southeastern periphery of the range of this species. Plants occurring at the periphery of a species’ range are thought to be of special conservation importance. Peripheral populations are usually smaller and less genetically diverse within the population, but genetically divergent from centrally located populations. These genetic differences may confer special survival traits that plants in other portions of the species’ range lack, such as the ability to survive changes in the climate or the arrival of a new pathogen. Peripheral populations may be in the process of evolving into a new species. They are especially deserving of conservation action.
Protect known populations from logging, mining, and other forms of habitat destruction and fragmentation.
Augsperger, C.K. 2004. Developmental versus environmental control of early leaf phenology in juvenile Ohio buckeye (Aesculus glabra). Canadian Journal of Botany 82(1): 31-36. https://www.nrcresearchpress.com/doi/abs/10.1139/b03-121
GADNR. 2019. Element occurrence records for Aesculus glabra. Georgia Department of Natural Resources, Wildlife Resources Division. Social Circle, Georgia.
Hicks, D.J. and M.S. Taylor. 2015. Effects of Aesculus glabra canopy on understory community structure and environment in a temperate deciduous forest. Castanea 80(1): 8-19. https://bioone.org/journals/Castanea/volume-80/issue-1/14-024R3/Effects-of-Aesculus-glabra-Canopy-on-Understory-Community-Structure-and/10.2179/14-024R3.full
Hilty, J. 2019. Species account for Ohio Buckeye, Aesculus glabra. Illinois Wildflowers. Accessed 25 June 2019. https://www.illinoiswildflowers.info/trees/plants/oh_buckeye.htm
NatureServe. 2019. Species account for Aesculus glabra. NatureServe Explorer: an online encyclopedia of life, Version 7.1. NatureServe, Arlington, Virginia. Accessed 25 June 2019. http://explorer.natureserve.org/servlet/NatureServe?searchName=Aesculus+glabra
Weakley, A.S. 2015. Flora of the southern and mid-Atlantic States. University of North Carolina Herbarium, University of North Carolina, Chapel Hill.
Williams, R.D. 1990. Aesculus glabra Willd., Ohio Buckeye. In, Silvics of North America, Volume 2, Hardwoods. Agriculture Handbook 654. U.S. Department of Agriculture, Forest Service. Accessed 25 June 2019. https://www.srs.fs.usda.gov/pubs/misc/ag_654/volume_2/aesculus/glabra.htm
Linda G. Chafin
25 June 2019
