180 PLANT DISTEIBTJTION. 



Trifolium subterraneum abounds — there had been a continual in- 

 terchange of stock, crops, &c. , and from this I took my cue. Either 

 as stowaways in fodder, or attached to the coats of live stocky 

 the "seed had been brought from Penzance to the place where I 

 had found them growing. In spite of the special contrivance 

 which this plant possesses for burying its seed, it failed to 

 establish itself with us. 



Such then, in brief, are a few of the means by which plants 

 are locally distributed. But other and more important issues 

 underlie the above lists than a local interchange per se ; and 

 questions suggestive of a broad field for inquiry arise on a 

 careful comparison of the wanderers which have become 

 established in the district with those which failed to obtain a 

 permanent footing on the soil. Why should the Henbane, 

 Borage, and Bugloss, all of which grow profusely in other parts 

 of Cornwall, fail to make a home in the district ? and why should 

 the Balm-leaf, Fig-wort, the Pale-blue Toad-flax, and the 

 Mediterranean Heath become naturalised ? The nutlets of the 

 first three are never scattered far from the plants, and the plants 

 which grew in the district produced nutlets in abundance. 

 Again, why did not Trifolium subterraneum and Trifolium 

 arvense, both of which are common on our coasts, persist, when 

 the Monkey plant and the Canadian pond- weed, natives of North 

 America, manage to carry everything before them ? 



There can be no manner of doubt that climatologieal and 

 physical influences, in conjunction with great and wide-spread 

 movements of the earth, are responsible for the well defined 

 botanical regions which may be traced in both the Old and New 

 Worlds. Plants requiring high temperature to blossom and 

 fruit could not live within the Arctic circle or amid the eternal 

 snows of lofty mountains, and vice versa. But great as these 

 considerations are when applied to the flora of widely separated 

 countries, or to plants of such extremes of habit as those which 

 keep to mountain tops and those which love to bloom in sunny 

 dells, they do not seem to sufiice for the problem under consider- 

 ation. The climatologieal and physical conditions of Falmouth 

 and neighbourhood differ little from those of the Kennall 

 Valley; yet, while tolerably common at the first place, the 



