570 ARBORETUM AND FRUTICETUM. PART IIT. 
Diemen’s Land shrub, with yellow flowers 
which have the vexillum copper-coloured. It 260 
aoxs 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. 
Mirbélia reticulata Smith (Bot. Mag., t.1211., and our fig. 260.) 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 as to half-hardy 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- 
gions, very wet or clayey soils, and re-, 
tentive subsoils. As a proof of the truth , 
of what we state, we have only to refer 
to such plants as the common myrtle, 
Corre‘a alba, Coronilla glatca, Pittéspo- 
rum Jobira, 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 Baxus 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. ; 


