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 the colossal Cereus giganteus, whose straight stems when old are as firm as iron, and rise with many ascending arms or rear their tall leafless trunks like ships’ masts to a height of 60 ft. or 70 ft.  From this we descend through a multitude of various shapes and sizes to the tiny tufted Mamillarias, no larger than a lady’s thimble, or the creeping Rhipsalis, which lies along the hard ground on which it grows, and looks like hairy caterpillars.  In form, the variety is very remarkable.  We have the Mistletoe Cactus, with the appearance of a bunch of Mistletoe, berries and all; the Thimble Cactus;