HOUSE-LEEKS AND STONECROPS 103 



The name Semper vlviim, meaning *' ever-living," is 

 not inappropriate for the House-leeks. It is true that 

 the individual rosettes do not live beyond a few 

 years at most, but their place is constantly being 

 taken by new rosettes. The result is, the colony 

 presents much the same appearance from year to 

 yeai' at each season. The old, dead rosettes persist 

 for a long time beneath the new rosettes, and 

 go to increase the humus and thus enrich the poor 

 soil on which these plants manage to flourish. 

 Even the withered flower- stalks of the previous 

 year often remain attached to the rosettes. Many 

 small wind-blown particles of vegetable matter 

 and dust also collect round the colony, and thus 

 the soil constantly receives fresh additions from 

 without. 



Other rock plants, which play an important part 

 as colonisers of fresh ground, are the Stonecrops or 

 Sedums, belonging to the same natural order as the 

 House-leeks, and, like them, fleshy, succulent-leaved 

 plants adapted to dry habitats, and some of the 

 Saxifrages which we have already considered in 

 Chapter III. In the Edelweiss, discussed in Chapter 

 I., we have a typical rock-plant of a different habit, 

 but equally adapted to similar dry situations, though 

 not a frequent coloniser. 



We may now turn to Alpine species which not 

 only occur on rocky ledges, but are also frequent on 

 dry stony and semi-bare patches in the pastures, on 

 the bare moraines of glaciers, or on the debris of 



