h which most of us are familiar, and, by observing the
structure of its flowers, obtain some idea of the botanical characters
of the whole order.

Phyllocactus has thin woody stems and branches composed of numerous long
leaf-like joints, growing out of one another, and resembling thick
leaves joined by their ends. Along the sides of these joints there are
numerous notches, springing from which are the large handsome flowers.
On looking carefully, we perceive that the long stalk-like expansion is
not a stalk, because it is above the seed vessel, which is, of course, a
portion of the flower itself. It is a hollow tube, and contains the long
style or connection between the seed vessel and the stigma, a (Fig. 2).
This tube, then, must be the calyx, and the small scattered scale-like
bodies, b (Fig. 2), which clothe the outside, are really calyx lobes.

[Illustration: FIG. 2.--FLOWER OF PHYLLOCACTUS, CUT LENGTHWISE.

a, Calyx Tube. b, Calyx Lobes. c, Ditto, assuming the form of Petals. d,
Stamens. e, Style. f, Ovary or Seed Vessel.]

Nearer the top of the flower, these calyx lobes are better developed,
until, surrounding the corolla, we find them assuming the form and
appearance of petals, c (Fig. 2). The corolla is composed of a large
number of long strap-shaped pointed petals, very thin and delicate,
often beautifully coloured, and generally spreading outwards. Springing
from the bases of these petals, we find the stamens, d (Fig. 2), a great
number of them, forming a bunch of threads unequal in length, and
bearing on their tips the hay-seed-like anthers, which are attached to
the threads by one of their points. The style is a long cylindrical
body, e (Fig. 2), which stretches from the ovary to the top of the
flower, where it splits into a head of spreading linear rays, 1/2 in. in
length. When the flower withers, the seed vessel, f (Fig. 2), remains on
the plant and expands into a large succulent fruit, inside which is a
mass of pulpy matter, inclosing the numerous, small, black, bony seeds.

It must not be supposed that all the genera into which Cactuses are
divided are characterised by large flowers such as would render their
study as easy as the genus taken as an illustration. In some, such for
instance as the Rhipsalis, the flowers are small, and therefore less
easy to dissect than those of Phyllocactus.

The stems of Cactuses show a very wide range of variation in size, in
form, and in structure. In size, we have