[Illustration:  Fig. 54.  Melocactus communis.]

M. depressus (flattened); Bot.  Mag. 3691.—­Stem broader than high, deeply cut into about ten broad furrows, along the sharp angles of which are clusters of pale brown spines, from 1/2 in. to 1 in. long, arranged in a star, each cluster 1 in. apart.  Instead of the cylinder-like cap of the Turk’s-Cap species, this one has a short, broad tuft of white wool and red spines, like a skull-cap.  The flowers are small, and soon wither, but remain attached to the oblong berries, which stand erect in a dense cluster in the centre of the cap, and are of a delicate rose-colour.  The first introduced plant of this was sent home by Mr. Gardner, who introduced the Epiphyllums and other Cactuses.  It flowered on the way to England, and matured its seeds soon after its arrival.  It is a native of Pernambuco.

M. Miquelii (Miquel’s); Fig. 55.—­This species appears to have been introduced in 1838, when two plants of it were sent from the West Indian Island, St. Croix, to the Hamburg Botanic Gardens.  The stem is oval, dark green, with fourteen well-defined ribs, as regular as if they had been carved with a knife.  The spine-tufts are small; spines short, black-brown, about nine in each tuft, one of which is central, the others radiating; they are less than 1/2 in. long.  The “cap” is cylindrical, 3 in. high by 4 in. in diameter, and composed of layers of snow-white threads, mixed with short reddish bristles.

[Illustration:  Fig. 55.  Melocactus Miquelii.]

These three are the only species of Melocactus that have become known in English gardens, although various other kinds, named M. Lehmanni, M. Zuccarini, M. Ellemeetii, M. Schlumbergerianus, &c., occur in books.

CHAPTER X.

THE GENUS PILOCEREUS.

(From pilos, wool, and Cereus, in allusion to the long hairs on the spine cushions, and the affinity of the genus.)

One of the most striking plants in this order is the “Old Man Cactus,” botanically known as Pilocereus senilis, which is the only member of this genus that has become at all known in English gardens.  In Continental gardens, however, more than a dozen species are to be found in collections of succulent plants; and of these one of the most remarkable is that represented at Fig. 56.  The limits of the genus Pilocereus are not definitely fixed, different botanists holding different views with respect to the generic characters.  Recent writers, and among them the late Mr. Bentham, sunk the genus under Cereus; but there are sufficiently good characters to justify us in retaining, for garden purposes, the name Pilocereus for the several distinct plants mentioned here.  The botanist who founded the genus gives the following general description of its members:  Stems tall, erect, thick, simple or branched, fleshy, ridged; the ridges regular, slightly tubercled, and placed