ld, are not at all ornamental.

CHAPTER VII.

THE GENUS ECHINOCACTUS.

(From echinos, a hedgehog, and Cactus.)

Many of the plants included in the genus Echinocactus are very similar
in habit and stem-characters to the Cereus. Botanists find characters in
the seed vessel (ovary) and in the seeds by which the two genera are
supposed to be easily separable; but, so far as can be made out by a
comparison of their more conspicuous characters, there is very little
indeed to enable one to distinguish the two genera from each other when
not in flower. A comparison of the figures given in these pages will
show that such is the case.

The name Echinocactus was given to E. tenuispinus, which was first
introduced into English gardens in 1825. The spiny character of this
species is surpassed by that of many of the more recently introduced
kinds; still it is sufficient to justify its being compared to a
hedgehog. Some of the kinds have spines 4 in. long, broad at the base,
and hooked towards the point, the hooks being wonderfully strong, whilst
in others the spines are long and needle-like, or short and fine as the
prickles on a thistle. The stems vary much in size and form, being
globose, or compressed, or ovate, a few only being cylindrical, and
attaining a height of from 5 ft. to 10 ft. They are almost always
simple--that is, without branches, unless they are compelled to form
such by cutting out or injuring the top of the stem; the ridges vary in
number from about five to ten times that number, and they are in some
species very firm and prominent, in others reduced to mere undulations,
whilst in a few, they are separated into numerous little tubercles or
mammae. The species are nearly all possessed of spines, which are
collected in bundles along the ridges of the stem. Generally, the
flowers are about as long as wide, and the ovary is covered with scales
or modified sepals. The fruit is succulent, or sometimes dry, and, when
ripe, is covered with the persistent calyx scales, often surrounded with
wool, and usually bearing upon the top the remains of the withered
flower. The position of the flowers is on the young part of the stem,
usually being perched in the centre, never on the old part, as in some
of the Cereuses. The flowers open only under the influence of bright
sunlight, generally closing soon after it leaves them.

The geographical distribution of the species, of which over 200 have
been described, extends