Sapindaceae

Deciduous trees or shrubs with opposite leaves and leaf scars; including Maples and Horse Chestnut. Native species widespread in temperate areas where they often are often the dominant tree species in upland forests, as well as wetlands, including floodplains. Non-native species are often planted as ornamentals and spreading, sometimes invasive.

Bark is usually smooth on young trees and often becomes shaggy, plated and or furrowed on mature trees.

Leaves may be simple and lobed or have multiple leaflets (compound). In species with compound leaves, the leaflets may project from either side of the main leaf stalk (pinnate), or may radiate outward from a common point, like the fingers on a hand (palmate). Leaves of some species unexpanded at flowering. Maples are among the most colourful forest trees when their leaves change colour in autumn. Stipules absent.

Flowers usually clustered, may be upright to drooping, and white, yellow-green or red. Plants with showy flowers are usually insect-pollinated, while those with small inconspicuous flowers are usually wind pollinated. Individual flowers may have both male and female flower parts, or only one of these. Sepals usually 4 or 5, separate or fused at the base, sometimes very reduced. Petals usually 4 or 5, separate or absent, very narrow at the base (clawed) in Horse Chestnut. Stamens usually 8 or fewer and separate, their stalks (filaments) usually hairy or covered with short projections (papillose). Carpels 2 or 3, stigmas 2 to 3. Fruit may be winged and in pairs (Maples), or may be a large prickly capsule containing a large nut-like seed that is shiny brown when ripe and has a broad pale scar (Horse Chestnut).