American mistletoe n 1: the traditional mistletoe of Christmas in America: grows on deciduous trees and can severely weaken the host plant [syn: {Phoradendron serotinum}, {Phoradendron flavescens}] 2: small herb with scalelike leaves on reddish-brown stems and berrylike fruits; parasitic on spruce and larch trees [syn: {Arceuthobium pusillum}]