570 



ARBORETUM AND FRUTICETUM. 



PART III. 



260 



261 



Diemen's Land shrub, with yellow flowers 

 which have the vexilluni copper-coloured. It 

 grows to the height of 4 ft., and flowers from 

 May to August. There are 14 species, all from 

 the same part of the world ; and all, doubtless, 

 half-hardy in the climate of London. In con- 

 sidering what may be the degree of hardiness 

 of plants, natives of foreign countries, it must be 

 remembered that the constitution of every plant 

 has an absolute and a relative character ; the 

 former can only be known experimentally by 

 culture in different countries, or by noticing it 

 in a wild state in different climates, and lo- 

 calities ; but the latter may be judged of by 

 observing how a plant accommodates itself to 

 the climate and locality in which it may exist 

 for the time being. Hence a number of plants 

 which appear tender are only relatively so, from 

 having been grown in a warm climate; while 

 the same plant, reared in a cold climate, would be absolutely 

 hardy. The common yew, for example, as Dr. Walker has men- 

 tioned, grown in France, proved quite tender when taken to 



Stockholm ; though the yew, as it is well known, is indigenous to Sweden. Plants, therefore, which 



are natives of Van Diemen's Land may, in the course of two or three generations, without altering 



their nature, be found as hardy as natives of Scotland. 



Mirbi/'ia rclicuh'ita Smith {Bot. Mag., t. ISJU., and our Jig. 2f)0.) is a handsome New Holland 



shrub, with lilac flowers ; and there are several other Australian species of this genus, all beautiful, 



and all deserving culture, though requiring some protection during winter. 



General Remarks a.i to half-hardi/ Species. — We may observe here, what to 

 many will appear sufficiently obvious, that plants half-hardy in the climate of 

 London will, in general, be quite hardy in the warmest parts of Devonshire 

 and Cornwall ; and will gradually require 

 less and less protection than they do 

 about London, as we proceed farther 

 southward ; always excepting, however, 

 particular localities, such as elevated re- / i </ , 

 gions, very wet or clayey soils, and re-; \'y'||i 

 tentive subsoils. As a proof of the truth 

 of what we state, we have only to refer 

 to such plants as the common myrtle, 

 Corrae^a alba, Coronillaglauca, Pittospo- 

 rum Tobira, the edwardsias, &c., which 

 all thrive against walls in the neighbour- 

 hood of London, but require a slight pro- 

 tection during frost ; while at Dartmouth, 

 Plymouth, Mount Edgcumbe, Powder- 

 ham Castle, Mamhead, Carclew, and 

 other well-known places, they are shrubs 

 as hardy as -Buxus balearica is near the 

 metropolis. As we proceed northwards, 

 it will be found that plants adapted for a conservative wall in the climate of 

 London may be divided into three kinds : the more tender, which will require, 

 in the colder situations, to be kept in the green-house or conservatory, such 

 as eutaxia ; the less tender, which will grow against a wall, in low situations 

 near the sea, as far north as Inverness, such as pittosporum, with the same 

 protection as they require about London ; and the hardiest, which may be 

 preserved against a wall, with very little more protection than what they 

 receive about London, in all ordinary situations in the north. Among this 

 latter kind may be included the myrtle, the camellia, edwardsia, psoralea, 

 &c., which, it is well known, require very little protection at Culzean Castle, 

 in Ayrshire ; at Ardgowan, near Greenock ; at Dundee, Montrose, Aberdeen, 

 Elgin, and Inverness. Even at Dunrobin Castle, these plants, and various 

 others, are grown in the open air, and kept alive through the winter with pro- 

 tection. The experience of gardeners in this most interesting part of their 

 profession is, as yet, in its infancy ; but it is not difficult to foresee that, as the 

 enjoyments afforded by conservative walls become better known, a knowledge 

 of their management, and of the principles of acclimatising plants, will be con- 

 sidered essential for every master-gardener. 



