36 NATURAL HISTORY OF PLANTS, 



lapponicus, they might well find it difficult to say how these plants 

 arrived at the furthest corner of the world. It may be questioned, 

 therefore, whether the great resemblance that these plants bore to- 

 those of Europe, did not mislead our great naturalists, in taking 

 them for the same, as they might have distinguishing characters 

 which, for want of comparing them with the European species, 

 they did not suppose. When Linnaeus and other botanists state va- 

 rieties of a plant to exist in different zones, they are not always to be 

 trusted ; for it has often been seen that such varieties had more con- 

 stant characters than many which by them are made species, sue! 

 that they did really constitute true species. Why should not Na- 

 ture, iu different degrees of latitude and longitude, have formed 

 species that exceedingly resemble one another 1 



In all countries there occurs a remarkable circumstance in the 

 history of plants, namely, that some grow gregariously, and some 

 singly ; that is, some always grow numerously and close together, 

 while others are scattered and grow quite solitarily. The 

 reason of this singular circumstance appears to He in the seeds 

 themselves, which are either too heavy for the wind to carry away, 

 or too light, so as to be destroyed by it, or the elasticity of the 

 capsule is not strong enough to throw them to a distance. The 

 root too of some vegetables is creeping, so that many plants of such 

 must always stand together. 



The gregarious plants sometimes occupy great tracts of ground. 

 The common heath (Erica vulgaris), extends often for many 

 miles. The whortleberry, (Vacciuium Mj/rtillus), the strawberry, 

 (Fragaria vescaj, some species of Pyrola, various rushes, (Junci) 

 and some trees are of tin's kind. Solitary plants are the Turritis 

 glabra, Anthericum Liliago, Lychnis dibica, and many others. 

 But when places are very populous, men have made great altera- 

 tions in this respect, by planting woods, and bringing plants close 

 together that would have stood separate, &c. The difference be. 

 tween gregarious and solitary plants is of consequence to those who 

 generally do not regard it. We give here for instance mosses, 

 which the forester and the economist trouble themselves less about 

 than they ought. Gregarious mosses are the Sphagnum palustre, 

 Dicranum glaucum, Polytrichum commune, and many others. 

 The solitary are, Poly tricum piliferum, all the species of Phascum, 

 Weissia paludosa, #c. 



