closely together.  Tubercles generally hairy, with bunches of short spines; the hairs long and white, especially about the apex of the stem, where they form a dense mass.  Flowers on the extreme top of the matured stems, and arranged in a cluster as in the Melon Cactus, small, tubular; the petals united at the base, and the stamens attached to the whole face of the tube thus formed, expanding only at night, and fading in a few hours.  These flowers have a disagreeable odour, not unlike that of boiled cabbage.  Fruit fleshy, round, persistent, usually red when ripe.  The species are natives of tropical America, and are generally found in rocky gorges or the steep declivities of mountainous regions.

Cultivation.—­These plants require distinctly tropical treatment.  During summer, they must have all the sunlight possible, and be supplied with plenty of water, both at the root and by means of the syringe.  Air should be given on very hot days, but the plants should be encouraged to make all the growth possible before the approach of winter.  In winter, they may be kept quite dry, and the temperature of the house where they stand should be maintained at about 60 degs., rising to 65 degs. or 70 degs. in the day.  In March, the plants should be repotted into as small pots as convenient, employing a good, loamy soil and ample drainage.  Should the hairs become soiled or dusty, the stems may be laid on their sides and then syringed with a mixture of soft soap and warm water, to be followed by a few syringefuls of pure water; this should cleanse the hairs and give them the white appearance to which the plants owe their attractiveness.

Species.

P. Houlletianus (Houllet’s); Fig. 56.—­Stem robust, glaucous-green; ridges about eight, broad, prominent, obscurely tubercled; spines in bundles of nine, radiating, straight, less than 1 in. long, and pale yellow.  Upon the growing part of the stem, the spines are intermingled with long, white, cottony hairs, often matted together like an unkempt head; these hairs fall off as the stem matures.  Flowers funnel-shaped, resembling Canterbury Bells, borne in a cluster on the summit of the plant; ovary short and scaly; petals joined at the base, and coloured a rosy-purple, dashed with yellow; the stamens fill the whole of the flower-tube and are white; style a little longer than the flower-tube, and bearing a ray of about a dozen stigmas.  Fruit globose, as large as a plum, and coloured cherry-red.  The pulp is bright, crimson, and contains a few brownish seeds.  In the engraving the fruit is shown on the left, and a flower-bud on the right.  This species is often known in Continental collections as P. Fosterii.

[Illustration:  Fig. 56.  Pilocereus Houlletianus.]