Aesculus hippocastanum is a large tree, growing to about 39 metres (128 ft) tall:371 with a domed crown of stout branches on old trees the outer branches are often pendulous with curled-up tips. The leaves are opposite and palmately compound, with 5–7 leaflets each leaflet is 13–30 cm long, making the whole leaf up to 60 cm across, with a 7–20 cm petiole. The leaf scars left on twigs after the leaves have fallen have a distinctive horseshoe shape, complete with seven "nails". The flowers are usually white with a yellow to pink blotch at the base of the petals they are produced in spring in erect panicles 10–30 cm tall with about 20–50 flowers on each panicle. Its pollens are not poisonous for honey bees. Usually only 1–5 fruits develop on each panicle the shell is a green, spiky capsule containing one (rarely two or three) nut-like seeds called conkers or horse-chestnuts. Each conker is 2–4 cm diameter, glossy nut-brown with a whitish scar at the base.