CACTUS FAMILY. 155 



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

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

 fine prickle-clusters : flowers smaller. 



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

 about 12-ribbed, disposed to stand when short, not rooting; iiower opening for 

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

 2' long, rather shorter than the tube. 



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

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

 red, open by day. 



§ 3. Stems erect, self-supporting, tall-growing, cylindrical and column-like, with 



about 8 (6- io) 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. Peruvi^nus. The largest species (except the Giant Cereus of Arizona), 



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



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



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



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



sometimes broken up into tubercles. 



* * Flower opening at nighty 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 sepals, 

 the upper 4' long, longer than the petals. 



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

 foregoing, but the tube not woolly. 



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

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

 petals and olive and brown-jKirple 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-Man 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, with a very sliort tube. 



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

 base : flower with very short bell-shaped tube. 



C. C9espit6sus. 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 funnel-shaped lube, 6'- 8' long, 

 to which an outer set of stamens is united up to the throat, while the inner ones 

 are separate far down : petals and sepals pointed. 



* Flower ivhitp. fragrant : calyx-tube ivith tnfls 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 ZuccauiniXnus. Stem broader than high, sunken at 

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

 ing 6-8 stout and dark spines. 



* * Flower ddicate rose-color : calyx-tube loith scattered hairs and the scales cdiate : 



stem somewhai pcar-ahapid or obovate, 6' - 12' high. 

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

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



