814 OPUNTIACEAE 



Stems erect : branches equally 3-8-angled. 



Branches 6-8-angled. 1. c. monodonos 



Branches 3-4-angled. 2. C.princeps. 

 Stems reclining or procumbent : branches climbing, unequally 3-5-sided. 



Central spine minute : radial spines conic : plants with aerial roots. 3. C. triangularis. 



Central spine 1-2 cm. long : radial spines subulate : plants without aerial roots. 4. C. Baxaniensis'. 



1. Cereus morioclonos DC. Stems columnar, 1-3 m. tall, erect, green, the ribs 6-8, 

 obtuse : spines brownish, radiant, varying from very short to 3.5 cm. in length : flowers 

 mainly white, 15 cm. long : fruit about 5 cm. long. 



In sand, peninsular Florida and the West Indies. 



2. Cereus princepa Pfeif. Stems erect, 1-3 m. tall, 5 cm. thick, 3-4-angled : areolae 

 distant: spines unequal; outer radiant, 4-6, stout, often 2.5-3.5 mm. long; central de- 

 flexed : flowers white, 17-20 cm. long, 13-15 cm. broad : fruit oval, 5-7.5 cm. long, spiny, 

 scarlet without, red and pulpy within : seeds 3-3.5 mm. long, smooth and shining. 



Along the lower Rio Grande on the Mexican side and probably on the Texas side. WUERZLE. 



3. Cereus triangularis ( L. ) Haw. Stems reclining or procumbent, elongated, 

 branched, the branches often rooting at the joints, 3-angled or with a flat side and 2 grooved 

 sides, the joints commonly 32 cm. long, 5-7.5 cm. broad, occasionally twisted, the ribs at 

 first wing-like, with remote areolae : spines 3-5, rigid, blackish, somewhat recurved, 2-4 

 mm. long, upper ones shorter than the lower : flowers white, 20 cm. broad : fruit commonly 

 10 cm. long, scarlet, smooth. 



In sand, peninsular Florida, the West Indies and Central America. 



4. Cereus Baxaniensis Karw. Similar to C. triangulai-is in habit, but lacking the 

 aerial roots. Stems sometimes 8 m. long, the joints various, a 3-angled one often arising 

 from a 5-angled one : spines 5-8, the radial bristle-like or subulate, brittle, the central 

 one 1-2 cm. long : flowers and fruit unknown. 



In sandy soil or coral rock, Florida Keys and the coasts of the West Indies and tropical America 



4. ECHINOCACTUS Link & Otto. 



Fleshy plants, with globular oblong or cylindric stems, with spine-bearing ribs or 

 vertical or spiral rows of tubercles. Leaves obsolete, flowers arising from areolae on the 

 tubercles near the areolae which later produce spines. Hypanthium with naked scales 

 or others bearing wool in their axils, prolonged beyond the ovary. Petals numerous, 

 merging into the sepals. Ovary 1-celled: style columnar. Stigmas slender, numerous. Berry 

 fleshy or dry, with scales, or tufts of bristles. Seeds often with endosperm. Embryo curved. 



Spines, especially the central, very slender, terete. 



Ribs less than 10 : central spines 4. 1. E. Schottii. 



Ribs more than 12 : central spines 1-3. 2. E. setispinus. 



Spines, especially the central, stout, flattened. 



Central spines straight or slightly curved. 3. E. Texensis. 



Central spines hooked. 



Radial spines mostly 8 : central spines 5-15 cm. long : flowers 2.5-3.5 cm. long. 4. E. Wrightii. 

 Radial spines 10-12 : central spines 25-35 mm. long : flowers 5-7 cm. long. 5. E. Muhlenpfordtii. 



1. Echinocactus Schdttli (Engelm. ) Small. Stems ovoid or cylindric-ovoid, 10-15 

 cm. high, 5-7.5 cm. thick, usually solitary, the ribs often 8, oblique : spines all or some 

 variegated with red and white ; outer 15-17 radiant, straight, variable in length ; central 

 usually 4, of 2 kinds ; uppermost 3-4 cm. long, flat above, keeled beneath, straight or 

 slightly curved, the three lower ones much shorter, nearly terete or somewhat flattened, 

 straight : flowers mainly purple, 5-7.5 cm. long. [E. bicolor var. Schottii Engelm.] 



On limestone hills, southern Texas and adjacent Mexico. 



2. Echinocactus setispimis Engelm. Stems subglobose, solitary, 5-9.5 cm. in di- 

 ameter, the ribs 13, somewhat oblique, more or less undulate or even slightly interrupted : 

 spines various ; radials 14-16, bristle-like, 1-2 cm. long, the upper longer than the rest and 

 like the lower, yellowish brown, the lateral ones white ; centrals 1-3, darker than the 

 radials, 24-32 mm. long, bristle-like : flowers 4-7 cm. long, yellow and scarlet within : 

 fruit subglobose, about 8 mm. in diameter, red : seeds obliquely globose-ovoid, 1.2-1.6 

 mm. long, tuberculate. 



In mesquite thickets and dry soil, from the valley of the Brazos, Texas, southward into Mexico. 



3. Echinocactus Texensis Hoepf. Stems depressed or rarely subglobose, 2-3 dm. 

 broad, seldom over 15 cm. high, solitary, simple, the ribs 13-27, usually 21, wavy : spines 

 reddish, stout, flattened, clustered ; radials 6-7, straight or slightly curved, spreading, 12-20 

 mm. long, rarely longer or shorter ; central one surpassing the outer, commonly 4-5 mm. 

 broad or slightly broader, straight or slightly curved : flowers orange and scarlet below to 



