CHAPTER II.

BOTANICAL CHARACTERS.



Although strictly botanical information may be considered as falling
outside the limits of a treatise intended only for the cultivator, yet a
short account of the principal characters by which Cactuses are grouped
and classified may not be without interest.

From the singular form and succulent nature of the whole of the Cactus
family, it might be inferred that, in these characters alone, we have
reliable marks of relationship, and that it would be safe to call all
those plants Cactuses in which such characters are manifest. A glance at
some members of other families will, however, soon show how easily one
might thus be mistaken. In the Euphorbias we find a number of kinds,
especially amongst those which inhabit the dry, sandy plains of South
Africa, which bear a striking resemblance to many of the Cactuses,
particularly the columnar ones and the Rhipsalis. (The Euphorbias all
have milk-like sap, which, on pricking their stems or leaves, at once
exudes and thus reveals their true character. The sap of the Cactuses is
watery). Amongst Stapelias, too, we meet with plants which mimic the
stem characters of some of the smaller kinds of Cactus. Again, in the
Cactuses themselves we have curious cases of plant mimicry; as, for
instance, the Rhipsalis, which looks like a bunch of Mistletoe, and the
Pereskia, the leaves and habit of which are more like what belong to,
say, the Gooseberry family than to a form of Cactus. From this it will
be seen that although these plants are almost all succulent, and