Conkers come from the horse chestnut tree (Aesculus hippocastanum) . The horse chestnut tree is a tall, broad tree of woodlands, roadsides, and parks, and it is an introduced, but naturalized species. The seeds of the horse chestnut tree are similar to those of the sweet chestnut tree, but the two trees are not related. The seeds of both trees come in green shells, but horse chestnut seeds are shinier and brown, and they appear in their spiny cases in autumn. Conkers are used to play the traditional childrens game called "conkers" in Great Britain and Ireland.