26 Postelsia 
small dry crevices of the slate rock, and in spite 
of the precarious foothold flourish better than 
farther back where competition with other forms 
is more sharp. 
6b. Protected rocky beaches. 
These are of two principal ‘ands >) iirc 
those protected by elevation and distance from 
the sea and second, those protected by project- 
ing points or shelves of rocks: ‘Nhe formmermas 
characterized by a more or less scanty depos- 
ition of soil towards the front and by well estab- 
lished turf towards the back. On the patches 
of soil and in the crevices where soil has ac- 
cumulated is found a group of plants which may 
well be designated as a society of rock peren- 
nials. The species abounding here are:- 
Panicum unciphyllum Fragaria chiloensis 
Descham psia caes pitosa Trijolium heterodon 
Allium cernuum Prunella vulgaris 
Rumex salicijolius Castilleja acuminata 
Sagina occidentalis Achillea lanulosa 
Aster joliaceus 
This association is succeeded in passing to- 
