they are so very sharp and penetrating that even a gentle
touch is sufficient to make them pierce the skin. Once in they are very
difficult to get out; the very fine ones can only be shaved level with
the skin, and left to grow out, whilst the larger must be cut out if
they have penetrated to any depth. This horrid character in Opuntias,
whilst rendering them disagreeable to the gardener, has been turned to
good account in many of our colonies, where they are commonly used as
fences. A good hedge of such kinds as O. Tuna or O. horrida is
absolutely impassable to both man and beast, and as the stems are too
watery to be easily destroyed by fire, their usefulness in this way
could not be surpassed. As all the Opuntias will grow in the very
poorest of soils, and even on bare rocks, and as they grow very rapidly,
they have been largely employed in Africa, Australia, and India for
fences. It is reported that when an island in the West Indies was
divided between the French and English, the boundary was marked by three
rows of O. Tuna.

The flowers of Opuntias are not, as a rule, particularly attractive. In
many of the kinds they are large and well-formed, but the colours are
tawny-yellow, greenish-white, or dull red. These plants cannot,
therefore, be recommended for any floral beauty, although it is probable
that the same flowers, on plants of less repulsive appearance than
Opuntias are, as a rule, would be admired. There are a few exceptions to
this in such species as O. Rafinesquii, O. missouriensis, and O.
basilaris, which are compact and dwarf, and bear numerous large,
brightly-coloured flowers. The fruits of Opuntias, or, at least, some of
them, are edible, and to some palates they are very agreeable. We have
tasted them, and consider they are mawkish and insipid--not much better
than very poor gooseberries. Sir Joseph Hooker has compared them to
Pumpkins. They are pear-shaped, with a thick, spine-covered rind,
containing green, yellow, or red pulp, with small, hard seeds scattered
through it.

The fruit of Opuntia differs in character and structure from the
ordinary kind of fruit, such as apples, pears, &c. It consists of a
branch, or joint, modified in form, and bearing on its flattened apex a
flower, with the ovary buried in a slight depression in the fleshy
joint. After becoming fertilised, the ovary grows down into the joint,
and, ultimately the whole joint is changed into a succulent, juicy,
often coloured "fru