72 ALPINE PLANTS. 
get to the plant they will be sure to eat out 
the centre crowns, then only a few leaves 
will appear the following year. Top-dress in 
the autumn and spring with fine, broken 
limestone, letting it run well between the 
stones. PP. Scheuchzeri requires similar treat-— 
ment. Most of the other species will do in 
ordinary loam and sand. 
POLEMONIUM CONFERTUM (WV. W. America). 
A handsome little plant and worth growing 
on the rockery, requiring a well-drained place, 
south-west aspect, good loam, leaf-mould, and 
sand. It should be divided every second or 
third year and given a fresh place, otherwise 
it will die out. 
POTENTILLA NITIDA AND VARIETIES 
(Europe). Purely rock plants, and succeed 
well on a south or south-west aspect. They 
should be planted on an elevated piece of 
ground, either with a flat surface or between 
stones—not too high from the path edge or 
you will lose the beauty of the flowers—in grit, 
leaf-mould, and loam mixed in equal pro- 
portions. They require top-dressing once or 
twice a year; run a portion of fine grit among 
the leaves and stems, or they will grow out of 
