SAPINDACEAE - - Soapberry Family

Aesculus flava Solander — Yellow Buckeye

Yellow Buckeye (Aesculus flava) is a large tree, commonly 60 to 90 feet in height, with a trunk 2 to 3 feet in diameter; branches, somewhat pendulous, forming an oblong, round crown. The National Champion has a circumference of 296 inches, a height of 94 feet, and a crown spread of 69 feet. This is one of our largest and most important cove hardwood forest trees, along with Tuliptree Liriodendron tulipifera.

Separating Characteristics

Large tree; leaves opposite, deciduous, palmately compound with mostly 5 but occasionally 7 leaflets; flowers with 4 yellow petals, markedly unqual in size, petal margins villous; stamens about as long as the side petals, included or barely exserted beyond the corolla; fruit smooth, 5-8 cm in diameter; Calyx and pedicels stipitate-glandular.

I feel a few words concerning the buckeyes, in general, and the flower color of buckeyes would be helpful here. Evidently, there is a lot of hybridization within Aesculus in the South, especially in the "broad hybrid zone" of north Georgia. This term and a plausible theory to explain the hybridization in buckeye was published in 1989 & 1990 by Claude W. DePamphilis and Robert Wyatt. One of their theories explains that as the ruby-throated hummingbird (Archilochus colubris) migrates north from the Coastal Plain through the Piedmont in the early spring, when both A. pavia and A. sylvatica (and perhaps also A. flava) are flowering, may carry viable pollen from A. pavia north to A. sylvatica and A. flava at that time. As a result, a large percentage of the buckeyes you see in north Georgia are hybrids. This is to explain the different colors which you will see in the buckeye flower. True A. pavia has flowers that have really red petals and sepals, A. sylvatica flowers are really pale yellow to greenish, and A. flava has yellow flowers when fresh. Therefore, when you encounter shrubs / small trees, that have flowers with pinkish-red petals and greenish sepals, it may be a hybrid between A. pavia and A. sylvatica. Then if you see medium to large trees with flowers that otherwise look like A. flava but are streaked with red, then it could be a hybrid between A. flava and A. pavia X sylvatica.

Habitat

On rich soil in river bottoms and on mountain slopes, usually occurring as an occasional tree in association with other hardwoods. Moist forests, up to nearly 2000m, especially prominent in seepy cove forests, in the Piedmont only in "montane" habitats. A broad Southern Appalachian endemic. A. flava is one of the largest, most massive, and commonest trees in Southern Appalachian coves, recognizable in winter by the bark of large plate-like slabs, thick twigs, and massive form.

Habitat information from:
Weakley, Alan S., Flora of the Southern and Mid-Atlantic States, Working Draft of 21 May 2015.

Native Range

Known as a "Broad Southern Appalachian Endemic," it is found from southeastern Pennsylvania, south through eastern Tennessee to northern Georgia and Alabama; also west from Pennsylvania through Ohio, and Indiana to southern Illinois.

The native range of Aesculus flava (Yellow Buckeye)

Kartesz, J.T., The Biota of North America Program (BONAP). 2015. North American Plant Atlas. (http://bonap.net/napa). Chapel Hill, N.C. [maps generated from Kartesz, J.T. 2015. Floristic Synthesis of North America, Version 1.0. Biota of North America Program (BONAP). (in press)].

The Georgia range of Aesculus flava (Yellow Buckeye)

Zomlefer, W.B., J.R. Carter, & D.E. Giannasi. 2014 (and ongoing). The Atlas of Georgia Plants. University of Georgia Herbarium (Athens, Georgia) and Valdosta State University Herbarium (Valdosta, Georgia). Available at: http://www.georgiaherbaria.org/.