EASILY GROWN ROCK PLANTS 93 
are hidden from view. I. sempervirens and its varieties 
are evergreen, I. semperflorens blooms almost incessantly, 
some flowers appearing even during mild periods of winter, 
There is a double-flowered form of semperflorens and 
several large-flowered varieties of sempervirens are obtain- 
able under such names as snowflake, grandiflora, superba, 
etc. I. gibraltarica has pale rose or lilac-tinted flowers, 
this also being almost a continuous winter-flowering plant. 
Pinnata is specially noteworthy on account of the fragrance 
of its flowers, but semperflorens is also fragrant. Any 
of the Iberis will root from cuttings, or may be increased 
by laying side branches under stones. Seeds germinate 
freely enough, but seedling plants are somewhat variable 
in habit, and occasionally a plant may be found to grow 
coarsely and produce less flowers than the better forms. 
If such a plant fails to make a good show after the second 
season, it may be well to discard it in favour of a more 
compact, free-flowering form. 
MERTENSIA.—Several species of Mertensias are well 
qualified for a place in our review of the plants that are 
of free and easy growth, although a few must be classed 
with the “choice ’”’ subjects that require somewhat care- 
ful treatment. M. alpina, M. lanceolata, M. paniculata, 
M. pulmonarioides and M. siberica are all free growing and 
all beautiful, and are especially useful in that they make 
themselves perfectly happy in positions lacking in sun- 
shine. Blue in varying shades describes the colouring 
of the pretty arching racemes or panicles of drooping 
blossoms, but in the case of M. siberica the flowers are 
first pink, gradually changing with age to a soft shade of 
