CRASSULACE^. 1 29 



often inert enough and uninteresting in themselves, but from 

 various circumstances, perhaps, irremovable, would by such 

 adornment become attractive and beautiful; and quaint old 

 trees and ruins may be enriched in their own style by the same 

 means. The natural habitats of the Houseleeks — housetops, 

 walls, rocks, and generally dry exposed stony or gravelly places 

 — at once suggest their fitness for the uses indicated. They 

 establish themselves easily in such places in nature ; and in 

 practice to fix them in any position is a very simple matter, all 

 that is needed to that end being a little clay and horse or cow 

 dung, well mixed, as for use in grafting, on which to stick the 

 offshoots, when, even if the surface is vertical, they may be left 

 to themselves \nthout any misgivings as to success. The 

 adaptability of some of the species to another and very different 

 use in flower-gardening has been noticed and taken advantage 

 of by some of our best gardeners recently, and is becoming 

 popular. I allude to the new method of bedding out, in which 

 various Sempervivums are used to define intricate geometrical 

 figures in beds or borders, the spaces being filled, according to 

 the taste of the parties concerned, with flowering plants, or 

 with plants of different foliage, with a view to the produc- 

 tion of contrasts in form or combinations of colour and form ; 

 and for defining with precision intricate lines and figures, 

 there is perhaps nothing in the vegetable kingdom more fit 

 than these peculiar plants : but for this purpose they must be 

 used in single rosettes, which entails the necessity of their 

 being overhauled annually in spring, so as to remove all offsets 

 or young rosettes which would mar the lines. They are as 

 easily cultivated on flat surfaces on the ground-level as on any 

 elevation, and though adapted to exist on short commons, do 

 equally well in the richest soil, but it is always advisable to 

 drain well under them. 



S. arachnoideum [Cobweb Houseleek). — An extremely inter- 

 esting and curious plant. The rosettes are small, composed of 

 oblong sharp-pointed leaves, thickly set on both surfaces with 

 soft, short, glandular hairs. The tips of the leaves are con- 

 nected by radiating lines of delicate white threads, so inter- 

 woven with each other as to suggest the idea that a spider had 

 been at work upon them. The flower-stems rise a few inches 

 high. The flowers are pink, composed of twelve or more 

 spreading petals, and appear in July and August. Native of 

 the Alps and P}Tenees. 



S. arenarium {Sand Housekek). — The kaves in this species, 

 in small rosettes, are lance-shaped, smooth above and below, 



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