CACTUS FAMILY. 155 



§ 2. Stems and hranches long, weak, disposed to trail or creep, rematehj jointed, 

 cylindrical, with 8-12 rids or grooves and rows of approximated snort and 

 Jine prickle-clusters : /lowers smaller. 



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

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

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

 2' Jong, rather shorter than the tube. 



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

 rooting ; tiower 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 eolumn-like, with 

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

 9 - 1 2 m the cluster, and no long bristles : Jlower 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 pi'oportionally short. — Var. monstbuOsus, in old 

 conservatories, has a short stem with 4 -.8 irregular and wavy wing-likq angles^ 

 sometimes broken up into tubercles. 



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



C. eri6phorus. 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. repd.ndu.S. Stem with flatter ridges, and with flowers niuch as in the 

 foregoing, but the tube not woolly. 



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

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

 petals .md oiivo and brown-purple sepals, tliC 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 Cactds. 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 short tube. 



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

 base : flower with very short beU-sliaped tube. 



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

 becoming short^cyliridrical. 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. Echih6psis. 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 tube', 6' - 8' long, 

 to ifihich, an outer set of ^amens.is united up to the throat, while the 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, a6out 3' in diameter. 



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

 small bristly prick!e.s from woolly tubercles. 



C. tubiflorus, or ZuccAKiNiiNcs. Stem broader than liigh," sunken at 

 top, with 1 1 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. ox^gonus. Stem bluish, with about 14 acute ridges from a broad 

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



