C. reductus (dingy); Bot.  Mag. 4443.—­Stem erect, sometimes 3 ft. high, and about 4 in. wide, deeply furrowed, the furrows usually numbering about fourteen; the ridges tumid and irregular, and coloured a dingy glaucous-green.  Spines embedded in a tuft of grey wool, about a dozen spines in each cluster, 1 in. long, a few of them only half that length.  Flowers on the top of the stem, three or four opening together, each being 3 in. long and wide; the tube short and scaly, with overlapping sepals and saw-edged petals, which are white, slightly tinged with rose.  Stamens filling the whole of the flower-cup, bright yellow.  A native of Mexico, introduced in 1796, flowering in summer.  This species was evidently a favourite many years ago, but it is rare with us now.  It thrives in a house where the winter temperature does not fall below 45 deg., requiring no water at that time, but a liberal supply in the summer when growth is being made, and all the sunlight possible.  When without its star-shaped, handsome flowers, the stem is remarkably ferocious-looking, the spines upon it being quite as thick and as strong as on a hedgehog.

C. repandus (undulated); Fig. 28.—­Stem erect, 10 ft. or more high, unbranched, unless compelled to do so by the removal of the top.  Ribs eight or nine in number, rounded, somewhat undulated, and bearing spine-tufts nearly 1 in. apart; each tuft contains about ten spines, which are almost equal in length, fine, stiff, brown, and persistent; there is a little cushion of white wool about the base of the spines.  Flowers produced on the side, within a few inches of the top of the stem; they are composed of a scaly tube, 4 in. long, a circular row of spreading, incurved, pale brown sepals, and two rows of broad, overlapping, snow-white petals; stamens white, with yellow anthers; stigma yellow.  The flowers, developed in summer, are very beautiful, but, unfortunately, each lasts only a few hours.  A native of the West Indies, and an old introduction to English gardens (1720), but rare in cultivation now.  It requires the treatment of a stove all the year round.

[Illustration:  Fig. 28.—­Cereus repandus.]

C. Royeni (Royen’s); Bot.  Mag. 3125.—­This plant is not one of the handsomest as regards flowers; but its stems are ornamental, and the form of the flowers is such as would please those who admire the curious.  The stem is erect, several feet high, 2 in. in diameter, with about ten acute ridges, along which are little tufts of white wool about the base of the clustering spines, which are dark brown and 1 in. long.  The flower-tube is 2 in. long, thick, spineless, scaly, the scales becoming large near the top of the flower, where they form a cup-like whorl, enclosing the small rose-coloured petals, the stamens being white.  Introduced from New Grenada, in 1832.  It flowers in spring and summer.  It should be grown in a stove.