THE HORSE CHESTNUT FAMILY (Sapindaceae)

As with the sycamores and maples, the horse chestnuts were previously grouped into a separate family called Hippocastinaceae where they will still be listed in older references, but recent phylogenetic research has resulted in its inclusion into the Soapberry family (Sapindaceae). This reorganisation however results in a family with very few visible common characters so, although now considered to be a sub-family (Hippocasinoides), I am treating the the horse chestnuts separately. (Almost all other members of the previously separate family Sapindaceae are tropical.)

The sub-family Hippocastinoides is a small group of trees and shrubs, it’s most widespread genus being the horse chestnut or buckeye (Aesculus). Shoots of the Hippocastinoides are stout with resinous, often sticky buds. Leaves are palmate and compound (sub-divided into separate leaflets) leaves arranged oppositely and often very large. Flowers are showy, insect pollinated, with four or five petals fused into a lobed corolla tube and arranged in an upright, spike-like cluster The fruit matures to a capsule, usually globose, containing one to three large seeds (often erroneously called nuts) per capsule. The point of attachment of the seed in the capsule (hilum) shows as a large circular whitish scar. The capsule epidermis has spines or prickles in some species, while other capsules are warty or smooth. At maturity, the capsule typically splits into three sections to release the seeds.

(source: Wikipedia)