By noting the conditions in which plants are found growing in a natural
state, we obtain some clue to their successful management, when placed
under conditions more or less artificial; and, in the case of Cactuses,
knowledge of this kind is of more than ordinary importance. In the
knowledge that, with only one or two exceptions, they will not exist in
any but sunny lands, where, during the greater part of the year, dry
weather prevails, we perceive what conditions are likely to suit them
when under cultivation in our plant-houses.

Cactuses are all American (using this term for the whole of the New
World) with only one or two exceptions (several species of Rhipsalis
have been found wild in Africa, Madagascar, and Ceylon), and, broadly
speaking, they are mostly tropical plants, not-withstanding the fact of
their extending to the snow-line on some of the Andean Mountains of
Chili, where several species of the Hedgehog Cactus were found by
Humboldt on the summit of rocks whose bases were planted in snow. In
California, in Mexico and Texas, in the provinces of Central and South
America, as far south as Chili, and in many of the islands contiguous to
the mainland, the Cactus family has become established wherever warmth
and drought, such as its members delight in, allowed them to get
established. In many of the coast lands, they occur in very large
numbers, forming forests of strange aspect, and giving to the landscape
a weird, picturesque appearance. Humboldt, in his "Views of Nature,"
says: "There is hardly any physiognomical character of exotic vegetation
that produces a more singular and ineffaceable impression on the mind of
the traveller than an arid plain, densely covered with columnar or
candelabra-like stems of Cactuses, similar to those near Cumana, New
Barcelona, Cora. and in the province of Jaen de Bracamoros." This
applies also to some of the small islands of the West Indies, the hills
or mountains of which are crowned with these curious-looking plants,