The plant called “life everlasting” is one which grows in dry, open, sunny places. It clothes its leaves with silky hairs, and so prevents them from throwing off too quickly the small amount of water its roots are able to provide. Without this silky coat, the sun would suck its leaves quite dry of water. Sometimes a leaf has only a few of the little leaf mouths through which most of the water passes. As these mouths are wide open only in the sunlight, and as often the rest of the leaf is covered with a thick skin which prevents the water from slipping away (as a little of it nearly always does) through the cell walls, such a leaf will hold its water supply and keep fresh for a long time. Such leaves as these we find on what we call “evergreen” plants. The pines and hemlocks which light up the woods all winter have these thick-skinned, few-mouthed leaves, which throw off so little water that even when the ground is frozen hard, and gives no drinking water to the roots, they are able to keep fresh by the careful way in which each one hoards its own little supply. WOOLLY AND “DUSTY” LEAVES Curiously enough, some plants put on a hairy coat for just the opposite reason from the one which makes life everlasting clothe itself in that fashion. Life everlasting fears lest its leaves throw off their water, or perspire too quickly. Down by the stream that runs through the meadow grow great clusters of the pink-flowered steeple bush. If you look at the lower sides of the leaves of the steeple bush, you see that they are very woolly. As this wool is not between the sun and the leaf blade, it cannot be meant to protect the leaves from the heat of the sun; and indeed in this wet meadow, close to the river, never mind how quickly the leaves throw off their water, the roots can have no difficulty in finding close by more than enough to make good the loss. No, the fact is that these leaves need to throw off water very freely indeed to make room for the ever-fresh supply that is pushing up the stem, and their woolly covering is intended to help them do this very thing. Its object is to aid perspiration. In swampy places the moisture rises every night from the wet ground, and settles on the plants about. The little mouths on the under surfaces of the leaves of the steeple bush would soon be clogged with the moisture rising from below, if they were not protected in some way; and if they became so clogged, they could not throw off the water with which the whole plant is charged. Thus, by having this thick coat of hair, the water that otherwise would cling to the outer surface of the leaf blade is kept at a distance from the little mouths, and these are not interrupted in the performance of a duty so necessary to the health of the plant.