THE GREEN-HOUSE.—HYDRANGEA HORTENSIA. 93 
species of Mimulus have been found in their native habitats grow- 
ing in coarse sand or gravel on the brink of a river, this kind of soil 
should be chosen for them in pots; and the soil in which they are 
grown can hardly be too poor, provided they have abundance of 
water. In Chili, the inhabitants eat the leaves asa kind of vegetable. 
The shrubby kinds of Mimulus, viz., the common monkey plant, 
M. luteus, and the scarlet-flowered species, M. puniceus, are now 
considered to belong to a new genus called Diplacus. ‘They are 
both natives of California; and in their treatment they should be con- 
sidered as green-house plants, and have rather a better soil, and less 
water, than the true kinds of Mimulus. 
Hydrangea Hortensia is another plant, that when grown in a pot, 
requires to have the saucer kept half full of water. ‘There are seve- 
ral species, most of which are hardy shrubs, but Hydrangea Hor- 
tensia, the kind usually called the Hydrangea, is a native of China, 
and only half hardy, though it will live in the open air in sheltered 
situations, or with a very slight protection. This plant was named 
Iortensia by the botanist Commerson in compliment to Madame 
Hortense Lapeaute, the wife of a French watch-maker. The Hy- 
drangea, should be grown in a rich loamy soil, and pruned every 
year; all the old wood being cut out, so that the wood which is to pro- 
duce the flowering shoots should never be more than two or at most 
three years old. Cuttings strike readily at any season when the 
plant is in a growing state; if putinto a rich soil and kept moist, they 
will root in a fortnight, and flower in a month. The flowers of the 
Hydrangea, though generally pink, are sometimes blue ; and the art 
of making them blue at pleasure, has long been a desideratum among 
gardeners. A great number of recipes for this purpose have been 
given in gardening books, but though all of them are occasionally 
successful, none of them will ensure success. Sometimes transplant- 
ing Hydrangeas that have been grown in loam into peat, will have 
the desired effect; and at others, watering with water in which iron 
has been steeped will change the colour of the flowers. The ferru- 
ginous yellow loams of Hampstead Heath and Stanmore Common 
are almost always efficacious, but even these have been known some- 
times to fail. All that is known with certainty is, that the change 
of colour is only a variation, and not permanent, as cuttings taken 
from a blue Hydrangea, and planted in common soil, almost always 
produce pink flowers. 
