(from the Latin, but of uncertain application). Cactaceae. Usually arborescent, columnar cacti with the surface covered with spiny ribs.

Flowers large, borne singly along the sides of the stem; flower-tube slender and, as it decays, cutting off from the ovary; petals numerous; stamens numerous; style single, thick: fruit a large, naked, fleshy berry; seeds small, black. The genus Cereus, as it has generally been treated, contained more than 100 species which differed greatly in habit, armament, flowers and fruit, and was one of the most complex and difficult of the family. As now understood, it contains species of uniform habit, with similar flowers and fruits, while a number of species of very different habit have been referred elsewhere. Even as here treated, more than half of the species are anomalous. Until the flowers and fruits have been studied, it seems best to leave them in Cereus. The species are all from S. Amer.

Only a few species of true Cereus are grown in this country, and most of these are grown under glass. The flowers do not compare in size and attractiveness with those of the so-called night-blooming Cereus, which is described elsewhere under the genus Seleni-cereus. Several of the species have cristate and other abnormal forms which make them desirable to certain growers. C. lepidotus is a rather common cultivated species in certain of the West India Islands, where it grows to considerable height, and several of the species are grown in Europe along the Riviera, where they reach great size. With us, however, they do not grow very rapidly. They are easily propagated from seed or by cuttings. See Succulents.

The species treated in the first edition of this work that are not here given may be looked for under the following genera: Acanthocereus, Aporocactus, Ber-gerocactus, Carnegiea, Cleistocactus, Escontria, Har-risia, Heliocereus, Hylocereus, Lemaireocereus, Lopho-cereus, Myrtillocactus, Oreocereus, Pachycereus, Rathbunia, and Selenicereus.

A. stems erect, 2 in. or more diam.

B. New growth green, not pruinose or covered with a bloom.

c. Ribs of stem 10 or more.

1. Pasacana, Web

A gigantic species, reaching a height of 20-30 ft., and sometimes even 50 ft., and a diam. of 12-16 in.; sparingly branching above; in new growth dark green, becoming gray or bluish: ribs 15-20, or in young plants only 9-10: areoles3/8-3/4in. apart, large, brown, becoming yellowish and finally gray: radial spines 10-13, about 1 in. long, the under one or lowest pair straight, subulate, the others curved; centrals mostly 4, the under and upper ones the longest, reaching 2 in. length, straight or curved; the young spines are clear brown, often with alternating rings of light and dark tissue, later gray, bulbose at the base: flowers from the lateral areoles about 6 in. long, white. Argentina. - This is the giant cereus of the Argentine desert, as Carnegiea gigantea is of the certain N. American deserts. It is not a true Cereus.

2. Candicans, Gillies

stems upright, low, cylindrical, bright green, 2 1/2-3 ft. high by 6-8 in. diam.; freely branching from the base: ribs 10, obtuse - angled: areoles 5/8- 3/4in. apart, large, depressed, white, becoming gray: radial spines 11-14, spreading, at first thin, needle-form, later stronger, stiff, straight, about 3/4in. long; central solitary or later 3-4 additional ones appearing above, stronger, reaching a length of 1 1/4 in., sometimes somewhat curved; all the spines horn-colored, with tips and bases brown, later becoming gray: flowers long, funnelform, resembling those of Echinopsis, 10 in. long by 6 in. diam.: fruit spherical to ellipsoidal, about 3 in. diam., red, somewhat spiny, flesh white. Argentina. - Not a true Cereus.

3. Lamprochlorus, Lem

Related to C. candicans, of a taller growth, cylindrical, 3-6 1/2 ft. high by about 3 in. diam., at first simple, but later branching at the base; in new growth bright green, later dirty green: ribs 10-11 or occasionally 15; conspicuously crenate, later blunt and but little crenate: areoles medium size, about 1/2in. apart, yellowish white, becoming gray; above each areole 2 radiating grooves form a letter V: radial spines 11-14, spreading, straight, sharp-pointed, about 3/8in. long, clear to dark amber-color; some are strong and rigid, while others are bristle-form; centrals mostly 4, somewhat longer, stronger and deeper colored, with brown bases, becoming dark gray, about 3/4in. long: flowers from the previous year's growth, about 8-10 in. long by 6 in. diam., white. Argentina. - Not a true Cereus.

4. Spachianus, Lem. Sts

upright, at first simple, later profusely branching at the base, branches ascending parallel with the main stem, 2-3 ft. high by 2-2 1/2 in. diam., columnar: ribs 10-15, obtuse, rounded: areoles about 1/2in. apart, large, covered with curly yellow wool, becoming white: radial spines 8-10, 1/4-3/8 in. long, spreading, stiff, sharp, amber-yellow to brown; central solitary, stronger and longer; all the spines later becoming gray: flowers about 8 in. long by about 6 in. diam., white. Argentina. - Not a true Cereus.

5. Chiloensis, Dc

(Cactus chiloensis, Colla). stems strong, upright, simple (so far as known), about 2,1/2 ft. high by 3 1/2-5 in. diam., cylindrical to somewhat clavate, bright, clear green: ribs 10-12, obtuse: areoles about an inch apart, large: radial spines straight, sharp, rigid, at first 9, but later 4 others appear above these; centrals mostly 4, seldom but a single one, bulbose at the base; the young spines are brown honey-yellow, becoming white, with dark tips, and finally gray: flowers from the upper lateral areoles about 6 in. long, white, resembling those of Echinopsis. Chile. - This is not a true Cereus.

cc. Ribs of stem 7-9.

6. Euphorbioides,Haw

(C.Olfersii,Otto). Columnar, simple, 10-16 ft. high by about 4 1/2 in. diam., in young growth pale green, changing with age to gray-green: ribs 8-10, separated by sharp grooves, sharp-angled, becoming flattened in older growth: areoles about 3/8in. apart, small, white to gray: radial spines mostly 6, the under one the longest, reaching a length of over an inch, strong, yellowish brown to black, the upper ones shorter and bristle form; central solitary, in young plants twice as long as the radials; all the spines finally become gray: flowers from near the crown, 3 1/24in.long,beautiful flesh - red, remaining open for 24 hours. Brazil. R.H. 1885, p. 279. -This plant is insuffi-ciently understood; it may be a form of some species of Ceph-alocereus.