2S6 SUB-ALPINE PLANTS 



Distribution. — Almost all Europe. Introduced into Britain. 



Sometimes Cuscuta, or Dodder, is parasitical upon this plant. 

 In the Zinal valley in the hot summer of 1911 much of it was seen 

 on this rather unusual " host." 



LORANTHACE^ 



A family of over 600 species spread o\'er the greater part of 

 the world, but chiefly in the tropics. 



ViSCUM L. 

 About 30 species in the hot and temperate regions of the ancient 

 world. 



Viscum album L. Mistletoe. 



This well-known parasitical plant is very common in Switzerland, 

 growing not only on Apple, Poplar, Oak, etc., but .also upon Fir 

 and other Coniferous trees. 



It ascends to at least 4000 feet in some of the pine forests. 



Distribution. — Europe, Asia, N. Africa. 



CUPULIFEILE 



Trees or shrubs with alternate stipulate leaves. Flowers monoe- 

 cious. Male flowers in drooping catkins, sepals 4 or less, stamens 

 2-4 ; female flowers 2-3, under each scale of a catkin ; perianth 0. 

 Fruit indehiscent. 



A large family chiefly found in the temperate regions. 



Betula L. 



Stamens 2 ; scales of female catkin thin, deciduous, trifid. 

 Betula nana L. Dwarf Birch. 



A small dwarf shrub. Leaves very shortly stalked, nearly 

 orbicular, about \ inch long, very obtuse, crenate or serrate. 

 Catkins small and sessile, the males oblong, the females very short, 

 erect. 



Moors and bogs in the Alps and sub- Alps up to 6500 feet. May, 

 June. 



Distribution. — Central and Northern Europe, Northern Asia and 

 Arctic America. British. 



Betula pendula Roth. {B. alba L.). Silver or Common Birch. 



A small tree, 40-50 or rarely 70 feet high, with white papery bark 

 and glabrous ovate-acuminate, doubly serrate leaves. Fruit broadly 

 winged. 



Woods, marshes, and hills, up to the superior limit of the Beech. 

 April, May. In Scandinavia to the upper limit of Pines. 



