chestnut(Any north temperate fagaceous tree of the genus Castanea, such as Castanea sativa, which produce flowers in long catkins and nuts in a prickly bur)
catalyst(A substance whose presence alters the rate at which a chemical reaction proceeds, but whose own composition remains unchanged by the reaction. Catalysts are usually employed to accelerate reactions(positive catalyst), but retarding (negative) catalysts are also used)