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CEPHALOCEREUS. 



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Monvii.i.e;a sp. 



stems slender, sometimes 3 to 4 meters high, nearly simple, rather weak and often supported 

 by other plants, 3 to 5 cm. in diameter; ribs about 8, i cm. high; areoles i to 1.5 cm. apart; radial 

 spines about 10, somewhat unequal, the longest about i cm. long; central spines 2 or 3, km'ger and 

 stouter than the radial, usually about 2 cm. long, black at tip; flowers and fruit not seen. 



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J. N. Rose and George Rose near Guayaquil, Ecuador, August 



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This species was quite common in the flat country northwest of Guayaquil 



with a larger arborescent cactus, a species of Lemaircocereus, and at first was supposed to 



form. Unfortunately, no flowers or fruit were seen. Liv 



We are not certain of the generic position of this olant. but it so much 



flowered 



villea maritima in habit that we suspect that its relationship is here. 



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CEPHALOCEREUS 



1838. 



Cephalophorus Lemaire, Cact, Aliq. Nov. xii. 1838. Not Cephalophora Cavanille. 1801. 

 ^ ^"^ Pilocereus Lemaire, Cact. Gen, Nov. Sp. 6. 1839. 



Elongated cacti, various in habit, mostly columnar and erect, sometimes much branched with 

 a short trunk or in one species with spreading and procumbent branches; in some species the flower- 

 ing areoles develop an abundance of wool which confluently forms a dense mass called a pseudo- 

 cephalium either at the top or on one side near the top; in others long wool or hairs grow from the 

 areoles but a pseudocephalium is not formed; in others the flowers are produced in a circle at the 

 top and the bristles and fruit afterwards form a collar at the base of the new growth; in other species 

 neither wool nor hairs are produced in the flowering areoles; flowers nocturnal, short-campanulate to 

 \ short-funnelform or pyriform, straight or curved; perianth persisting on the ripening fruit, except in 



one species; fruit iisually depressed-globose, sometimes oblong; seeds black, smooth or tuberculate. 



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We know 48 species, distributed from southern Florida and northern Mexico to 

 I eastern Brazil and Ecuador. The type species is Cactus senilis Haworth, which is also 



the type of Lemaire's genera Cephalophorus and Pilocereus. The name Cephalocereits is 

 from the Greek, signifying headed-cereus, with reference to the pseudocephahum of the 



typical species. 



Key to Species. 



A. Flowering areoles confluent, forming a pseudocephalium. 



Pseudocephalium lateral. 

 r Ovary bearing few distant scales; areoles of the flower with tufts of short wool; 



plants simple, tall, columnar. 

 Plant cylindric; top rounded- bristles of pseudocephalium twice as long as wool . i. C senilis 



Plant tapering to the apex ;bnstles of pseudocephalium little longer than the wool. 2. C. hoppenstedtii 



Ovary naked. 



Plant unbranched .. . . . .' 3- C. purpureus 



Plant branched at the base. 



Ribs 12 to 17; flowers 6 to 7 cm. long 4. C fluminensis 



Ribs up to 23 ; flowers 4 cm. long 5- C. dybowskii 



Pseudocephalium terminal - 6. C, macrocephalus 



AA. Flowering areoles not confluent, though sometimes close together, not forming a pseu- 

 docephalium. 

 Flower-tube strongly bent about middle; areoles wholly without hairs; plant blue. . . 7. C. pentaedrophorus 

 Flower-tube straight or a Httle curved at the base. 



Ribs 10 to 18; flowers red. 



Ribs 15 to 18; perianth-segments not reflexed 8. C. polylophus 



Ribs 8; perianth-segments reflexed 9- C. euphorbioides 



r Ribs 4 to 13; flowers mostly whitish to purplish. 



Perianth falling away from the ovary by abscission .-. . . 10. C. russelianus 



Perianth withering-persistent (so far as known}. 



Ribs strongly tubercled. ^ 



Spines all brown, the radials widely spreadmg, the centrals stout, subulate ..11. C gounellei 

 Spines all yellow, acicular, the radials only slightly spreading 12. C zehntneri 



Ribs not tubercled. 



Flower- tube curved at base; areoles of the stem all densely long- woolly. ... 13. C. leucostele 

 Flower-tube straight; only flowering areoles, if any, long-woolly. 



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