CACTUS FAMILY. 155 



§ 2. Stems and branches long, weak, disposed to trail or creep, remotely jointed, 

 cylindrical, with 8-12 ribs or grooves and rows of approximated short and 

 Jine prickle-clusters : flowers smaller . 



C. serpentinus. Stems l' or more in diameter, tapering at the apex, 

 about I2-ribl)ed, disposed to stand when short, not rooting ; flower opening for 

 a night, fragrant, with linear petals reddish-purple outside, nearly white inside, 

 2' long, rather shorter than the tube. 



C. flagelliforniis. Stems long and slender, prostrate or hanging and 

 rooting ; lower 2' - 3' long, the narrow sepals and petals not very many, rose- 

 red, open by day. 



§ 3. Sletns erect, self-supporting, tall-growing, cylindrical and rolumn-lilce, with 

 about 8 (6-10) obtuse ribs and grooves, short mostly dark-colored prickles 

 9-^12 in the cluster, and no long bristles : flower large, white ; tube 3'- 6' long. 

 * Flower opening at midday, collapsing before night. 



C. Peruvianus. The largest species (except the Giant Cereus of Arizona), 

 becoming even 40° high and thick in proportion, Avith rather strong compressed 

 ribs and stout prickles ; the flower 6' Jong, with greenish sepals and white or 

 externally rose-tinged petals proportionally short. — Var. MONSTKuOsns, in old 

 conservatories, has a short stem with 4-8 irregular and- wavy wing-like angles, 

 sometimes broken up into tubercles. 



» * Flower opening at night, collapsing next day : tall stem narrower at the top. 



C, eriophorus. Stem jointed at intervals, with rounded ridges and needle- 

 like prickles ; flower 6' - 9' long, with woolly tube, and narrow greenish sejjals, 

 the upper 4' long, longer than the petals. 



C. repandus. Stem with flatter ridges, and with flowers much as in the 

 foregoing, but the tube not woolly. 



C. CSerulescenS. Stem bluish-green, becoming about 3' thick, with 

 rounded ridges and stoutish pricklfes ; flower 8' in diameter, "with eroded-toothed 

 petals and olive and brown-purple sepals, the longer of these little shorter than 

 the smooth tube. 



§ 4. Stem erect and simple, at length cylindrical, with 20 - 25 narrow ridges, bear- 

 ing clusters of short prickles and long bristly hairs. 



C. senilis, Old-JVLvn Cactus. Cult, for its singular appearance, the long 

 white hanging bristles at the top likened to the locks of an aged man ; flowers 

 (seldom seen) not large, Tvith a very short tube. 



§ 5. Stems short and dwarf, globular or oblong, clustered or branching from the 

 base: flower with very short bell-shaped tube. 



C. esespitdsus. Wild on the plains from Nebraska S. : 3' - 6' high, 

 becoming short-cylindrical, with 12-18 thick ribs, covered with the close 

 clusters each of 20 - 30 short and widely-spreading prickles ; flower rose-purple, 

 in daytime, 2' - 3' in diameter. 



§ 6. EcHiNOPSis. Stem globular or obovate, very proliferous, resembling Echino- 

 cactus, but flowering from the side ; the showy flowers usually open while 

 they last both day and night, and with a long Jmnel-shaped tube, 6' - 8' long, 

 to which an outer set of stamens is united up't'o the throat, while tlie inner ones 

 are separate far down ; petals and sepals pointed. 

 * Flower white, fragrant : calyx-tube with tufts of long brownish wool at each scale: 



globular stem depressed or sunken at top, about 3' in diameter. 

 C. Eyriesii. Stem with about 13 acute slightly wavy ridges, and many 

 small bristly prickles from woolly tubercles. 



C. tubifldrus, or ZuccARiNi^Nns. Stem broader than high, sunken at 

 top, with 11 very strong and prominent wavy ridges, the woolly tubercles bear- 

 ing 6-8 stout and dark spines. 

 » » Flower delicate rose-color : calyx-tube with scattered hairs and the scales ciliate : 



stem somewhat pear-shaped or obovate, 6' - 12' high. 

 C. os^gonus. Stem bluish, with about 14 acute ridges from a broad 

 base, and as many very short and unequal spines in the clusters. 



