In alluvial plains and on the banks of rivers trees are extremely useful as a check to the swift flow of the water in inundations, and the spread of the mineral material it transports; but this will be more appropriately considered in the chapter on the Waters; and another most important use of the woods, that of confining the loose sands of dunes and plains, will be treated of in the chapter on the Sands. Small Forest Plants, and Vitality of Seed. Another function of the woods, to which I have barely alluded, deserves a fuller notice than can be bestowed upon it in a treatise the scope of which is purely economical. The forest is the native habitat of a large number of humbler plants, to the growth and perpetuation of which its shade, its humidity, and its vegetable mould appear to be indispensable necessities. [Footnote: "A hundred and fifty paces from my house is a hill of drift-sand, on which stood a few scattered pines (Pinus sylvestris). Sempervivum tectorum in abundance, Statice armeria, Ammone vernalis, Dianthus carthusianorum, with other sand-plants, were growing there. I planted the hill with a few birches, and all the plants I have mentioned completely disappeared, though there were many naked spots of sand between the trees. It should be added, however, that the hillock is more thickly wooded than before. . . . It seems then that Sempervivum tectorum, etc., will not bear the neighborhood of the birch, though growing well near the Pinus sylvestris. I have found the large red variety of Agaricus deliciosus only among the roots of the pine; the greenish-blue Agaricus deliciosus among alder roots, but not near any other tree. Birds have their partialities among trees and shrubs. The Silvioe prefer the Pinus Larix to other trees. In my garden this Pinus is never without them, but I never saw a bird perch on Thuja occidentalis or Juniperus sabina, although the thick foliage of these latter trees affords birds a better shelter than the loose leafage of other trees. Not even a wren ever finds its way to one of them. Perhaps the scent of the Thuja and the Juniperus is offensive to them. I have spoiled one of my meadows by cutting away the bushes. It formerly bore grass four feet high, because many umbelliferous plants, such as Heracleum spondylium, Spiraea ulmaria, Laserpitium latifolia, etc., grew in it. Under the shelter of the bushes these plants ripened and bore seed, but they gradually disappeared as the shrubs wore extirpated, and the grass now does not grow to the height of more than two feet, because it is no longer obliged to keep pace with the umbellifera which flourished among it." See a paper by J.G. Buttner, of Kurland, in Berghaus s Geographicsches Jahrbuch, 1852, No. 4, pp. 14, 15.