22 Nature threatened 
the species has already been entirely- 
destroyed. 
The dwarf-palm {Chamaerops hu- 
milts) used to grow near Nice, which 
was the northern limit of this, our only 
European palm. It is constantly being 
uprooted there, however, by gardeners 
and builders. Thus, the limit has con- 
siderably receded towards the south ; 
and the species has almost vanished 
as a member of the Central European 
Flora (Ascherson and Graebner). 
The existence of even a common 
tree may be threatened by a great 
demand for its timber. In Sweden, 
the aspen {Populus tremula) is dis- 
appearing, as its timber has been 
largely used up in the production of 
matches. At present, aspen timber is 
imported for that purpose from Russia. 
The English custom of decorating 
their homes with mistletoe {Viscum 
album) at Christmas demands large 
quantities of this hemi-parasite. For 
