SMALLEE FOREST PLANTS. 285 



will be more appropriately considered in the chapter on the Wa- 

 ters ; and another most important use of the woods, that of con- 

 fining the loose sands of dunes and plains, will be treated of in 

 the chapter on the Sands. 



Small Forest Plcmts, amd 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 na- 

 tive habitat of a large number of humbler plants, to the growth 

 and perpetuation of which its shade, its humidity, and its vege- 

 table mould appear to be indispensable necessities.* We can not 



* "A hundred and fifty paces from my house is a hill of drift-sand, on 

 which stood a few scattered pines {Plnus 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., wiU 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 green- 

 ish-blue Agaricus deliciosus among alder roots, but not near any other tree. 

 Birds have their partialities among trees and shrubs. The Sylvice 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 saMna, 

 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 were 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 Geographisches Jahr- 

 huch, 1853, No. 4, pp. 14, 15. 



These facts are interesting as illustrating the multitude of often obscure 

 conditions upon which the life or vigorous growth of smaller organisms de- 

 pends. Particular species of trufiles and of mushrooms are found associated 

 with particular trees, without being, as is popularly supposed, parasites deriv 

 ing their nutriment from the dying or dead roots of those trees. The success 

 of Rousseau's experiments seem decisive on this point, for he obtains largei 



