A large, stately deciduous shade tree from the Balkan mountains of southeastern Europe, long planted across cool-temperate parks, avenues, and large lawns for its dramatic spring bloom and dense summer shade. In May it covers itself in upright, candle-like panicles of white flowers blotched yellow then pink, carried above big, coarse, palmately compound leaves of five to seven leaflets. By autumn it drops spiny green husks that split to release glossy mahogany-brown seeds — the 'conkers' of British schoolyard tradition. It is grand but high-maintenance and strictly ornamental: all parts, and especially those tempting shiny seeds, are toxic to people and livestock, and the tree is plagued by leaf blotch and the horse-chestnut leaf miner that brown the foliage by late summer. Do not confuse it with the unrelated, edible sweet chestnut (Castanea sativa) — that name overlap is a genuine and dangerous source of poisonings.