Mistletoe is an alien, an outsider in the plant world and a visitor, as it were, from an earlier earth development. It never touches the ground, growing on the branches of certain trees. It makes no effort to develop form and color in its floral organs, and its growth cycle is slow and reverse the normal cycle, with fruit ripening in mid-winter. Higher plants take their first step into life on earth by developing a root, which penetrates deep into the soil with vigor. Mistletoe also penetrates into its "soil," the branch of the host tree, to begin with; but as soon as the bark has been passed and the delicate, living cambium is reached, the process no longer moves toward the center. From, then on the joining lets the wood of the host form a wall around it and grows out toward the periphery as the branch thickens.