2S6 Scottish Mountain Plants. [Sess. 



rosaceous plant with prostrate branches and large, white, eight- 

 petalled flowers (Plate XXIV., Fig. 1). Among other mat 

 plants the Dwarf Birch (Betula nana) is characteristic, as 

 are also the following two Willows. Salix reticulata forms 

 large sheets, usually on rock ledges, and its branches creep 

 chiefly above ground or through a tangle of moss, &c. It 

 is easily known by its reticulated leaves. Salix herbacea 

 has the distinction of being the smallest shrub indigenous 

 to Britain, and it is frequently found on the barer and 

 higher ground of mountains. Its shoots spread beneath the 

 surface of the soil, and the leaves usually rise to less than 

 one inch high. This Willow can withstand much drought. 



All these mat growths prefer comparatively dry places, 

 and are not frequent where much surface-water is present. 

 As a rule, they occur on barren slopes and rocky ledges, and 

 shun the vicinity of rills and streams. They ascend to 

 higher altitudes than any other shrubby or woody forms. 



Rosette forms are represented on Scottish mountains by 

 such plants as Arabis petrsea, Saxifraga nivalis, S. stellaris 

 (Plate XXIV., Fig 2), Draba incana, and D. rupestris. This 

 growth is more noticeable if the plant consists of a single or 

 of few rosettes. Generally found in stony places, although 

 not strictly confined to these. 



Trailiyig Alpine herbs are not infrequent on the higher 

 slopes and screes. The two most conspicuous are the white- 

 flowered Cerastium alpinum and Saxifraga oppositifolia, a 

 plant with charming purple flowers produced early, even when 

 surrounded by the snow. Saxifraga aizoides, with brilliant 

 yellow flowers, ascends high, preferring damp positions. The 

 common white-flowered species, S, hypnoides, is likewise 

 found over a long vertical range. This Saxifrage is very 

 variable in habit : on screes or slopes of loose stones it often 

 occurs in small flakes. The small Epilobium alpinum is 

 often abundant on wet ground, sometimes with Sedum 

 villosum, Veronicas, &c. As a rule, these dwarf plants 

 chiefly affect moist situations. 



Cushion growths give a peculiar aspect to much of the 

 high mountain vegetation throughout the world. The cushion 

 habit is not confined to plants of any particular Natural 

 Order, nor is it believed that those forms originated in any 



