474 X. GENERAL REMARKS. 



phjrto-geography. In the general view, the various arti- 

 ficial climates of gardeners may be held to represent pass- 

 ably well the real climates of most countries that are 

 warmer or milder than Britain. Adding thereto our own 

 climate in its natural conditions, little is left unrepre- 

 sented except the intensities of winter cold and of desic- 

 cating summer heats ; neither of which does the gardener 

 wish to imitate here. 



Though wide cUmatal diversities are thus shown to be 

 necessary for the co-existence of the various plants con- 

 stituting the present flora of the globe, — another fact of 

 an opposite character is not the less true ; namely, that 

 many plants are adapted to endure and thrive under very 

 difi'erent climates. Species common to Britain and Sibe- 

 ria, to Britain and Africa, to Britain and Madeira, clearly 

 must be adapted to grow under very dissimilar conditions 

 of climate. But it is unnecessary to pass beyond the area 

 of Britain itself, to find this fact illustrated by examples. 

 A very few of which may suf&ce for illustration here. 



Festuca ovina on a gravel bank in Cornwall, or on a 

 chalk down in Kent, and the same species at four thou- 

 sand feet of elevation on the mountains of Scotland, — are 

 certainly placed under widely different conditions of cli- 

 mate. So likewise are Calluna vulgaris flourishing on the 

 low heaths of Cornwall, and Vaccinium Myrtillus growing 

 in woods which meet the sea-tides in Devon, — if compared 

 with other examples of the same shrubs at three thousand 

 feet of elevation on the hills of Aberdeenshire. The mean 

 temperatm-es of the whole year, — the means of the seve- 

 ral seasons, — those of the warmest and coldest months, — 

 those of the day and night, — the maxima and minima 

 of the j'ear, season, month, day and night, — the sum of 

 the daily temperatures, — all must differ much in those 

 very dissimilar situations. And yet the same species will 



