Hippocastanoideae

{{Short description|Subfamily of flowering plants}}

{{Automatic taxobox

| image = Gammel Holtegaard tree.jpg

| image_caption = Aesculus hippocastanum

| taxon = Hippocastanoideae

| authority = Dumortier

| subdivision_ranks = Genera

| subdivision =

• Acer
• Aesculus
• Billia
• Dipteronia
• Handeliodendron

}}

Hippocastanoideae is a subfamily of flowering plants in the soapberry family Sapindaceae.{{cite web |url=http://www.ars-grin.gov/cgi-bin/npgs/html/gnlist.pl?2226 |title=Genera of Sapindaceae subfam. Hippocastanoideae |work=Germplasm Resources Information Network |publisher=United States Department of Agriculture |access-date=2009-04-11 |url-status=dead |archive-url=https://web.archive.org/web/20150924052505/http://www.ars-grin.gov/cgi-bin/npgs/html/gnlist.pl?2226 |archive-date=2015-09-24 }} The group was formerly treated as the separate families Aceraceae and Hippocastanaceae. Molecular phylogenetic research by Harrington et al. (2005)Harrington, M. G., Edwards, K. J., Johnson, S. A., Chase, M. W., & Gadek, P. A. (2005). Phylogenetic inference in Sapindaceae sensu lato using plastid matK and rbcL DNA sequences. Systematic Botany 30: 366-382. [http://www.ingentaconnect.com/content/aspt/sb/2005/00000030/00000002/art00012 Abstract]. has shown that while both the Aceraceae and Hippocastanaceae are monophyletic in themselves, their removal from the Sapindaceae sensu lato would leave Sapindaceae sensu stricto as a paraphyletic group, particularly with reference to the genus Xanthoceras.

The most widespread genera are Acer (the maples) and Aesculus (the horse chestnuts and buckeyes). A feature of the subfamily is the palmate compound leaves.[http://delta-intkey.com/angio/www/hippocas.htm Hippocastanaceae] {{Webarchive|url=https://web.archive.org/web/20060318022212/http://delta-intkey.com/angio/www/hippocas.htm |date=2006-03-18 }} in L.Watson and M.J.Dallwitz. 1992 onwards. The families of flowering plants.