Please try our next iteration of the Michigan Flora Online here. Beginning on February 1, 2023, michiganflora.net will point to this new site.

The new site offers several benefits over the existing website, including real coordinate mapping, giving a clearer view of the density of documentation as well as more precision about plant distributions and their link to landforms. We will also have the ability to update species pages more regularly, both in terms of new collections and as more existing Michigan specimens are georeferenced. In addition, we have a better photo display, and offer indented keys.

A very easily recognized genus, with its opposite, palmately compound leaves and distinctive fruit. The latter is a capsule, the outside ± prickly (in our species) and only 1 or occasionally 2 (very rarely more) large seeds developing within. The seed has an unusually broad pale scar (hilum) representing the area of attachment; the rest of it is a shiny rich reddish brown when ripe.

Other species of Aesulus are cultivated for ornament, and A. parviflora Walter; a late-blooming shrub with a slender inflorescence with pure white petals and  long-exserted stamens several cm long is known to escape in adjacent Ontario and Ohio.

1. Leaflets 5, tapered ± gradually to tip; winter buds not glutinous; hilum not over 1/2 as broad as the diameter of the seed; flowers yellowish green.

A. glabra

1. Leaflets mostly 7, abruptly acuminate to a short tip; winter buds very glutinous; hilum about two-thirds or more as broad as the seed; flowers white.

A. hippocastanum