328 CACTACEAE (CACTUS FAMILY) 



prominent tubercles, which are 12-16 mm. long, somewhat quadrangular at 



i,l cylindric above: radial spines 20-30, slender, rigid, straight, whitish, 



mm. long, with 2-5 additional short setaceous ones above; central 



mines s 10, stouter, yellowish and reddish brown or black above, erect- 



spreading, 10-14 mm. long: flowers 16-20 mm. long and nearly as broad, 



vellowish-green to pale purple: fruit green and dry, 6-7 mm. long and almost 



iis broad: seeds black, obliquely obovate, tuberculate, 3 mm. long. Utah to 



3 Echinocactus Whipplei spinosior Engelm. Globose, 7.5 cm. in diam- 

 eter: ribs 13: radial spines 9-11, 12-36 mm. long, the lower ones often dusky, 

 the '2 upper ones of ten elongated, flattened, and curved; the 4 centrals 3.5-5 cm. 

 long, the uppermost one flexuous and white, the other 3 a little shorter, 

 dusky, all or only the lower one hooked: flowers about 2.5 cm. long: fruit oval, 

 12 mm. long. Southwestern Colorado. 



3. ECHINOCEREUS Engelm. 



Globose to cylindrical, simple or caespitose, sometimes very large, with 

 spine-bearing ribs. Flower-bearing areolae close above fully developed, spine- 

 bearing areolae. Ovary bearing bracts which are naked or woolly and always 

 spiny in the axils; stigmas always green. Fruit succulent. Seeds almost 

 without endosperm. Embryo mostly hooked, with short or foliaceous cotyle- 

 dons. Cereus. 



Flowers yellowish-green; ribs 12 or more 1. E. viridiflorus. 



Flowers not yellowish-green; ribs 5-12. 



Flowers violet-purple; central spine dark, terete . . . . 2. E. rendlen. 

 Flowers scarlet. 



Central spine angled. 



Ribs 5-7 . . 3. E. gonacanthus. 



Ribs 9-11 4. E. Roemeri. 



Central spine terete 5. E. aggregatus. 



1. Echinocereus viridiflorus Engelm. Wisliz. Mem. 91. 1848. Subglobose, 

 simple or sparingly branched, 2.5-7.5 cm. high: ribs 13, acute, scarcely in- 

 terrupted: radial spines 12-18 (with 2-6 setaceous upper ones), straight and 

 strictly radiant, 2-6 mm. long, laterals longest and reddish-brown, the rest 

 white (rarely purple) ; central none or a single stout, straight or curved spine 

 (rarely a second more slender one) 12-14 mm. long, variegated purple and 

 white: flowers 2.5 cm. long and wide, greenish-brown outside, yellowish- 

 green within; petals obtuse: fruit elliptical and greenish, 10-12 mm. long: 

 seeds 1-1.2 mm. long, tuberculate. Wyoming to New Mexico. 



2. Echinocereus Fendleri Engelm. PI. Fendl. 50. 1849. Ovate or ovate- 

 cylindrical, 7.5-20 cm. high, 5-7.5 cm. in diameter, simple or branching at 

 base, caespitose, dark green: ribs 9-12, straight or oblique, tuberculate, with 

 areolae s 14 mm. apart: spines stout, very variable in length and color; 

 radials 5-10 (mostly 7), straight or curved, lowest stoutest, white, and angu- 

 lar, 12-25 mm. long, next 2 almost as long (or longer), more terete, blackish 

 above and white beneath or all blackish, then 2 white or dark or variegated, 

 then 'J weaker, whiter, and shorter (6-14 mm.), often 2 more upper spines 

 and sometimes a slender or stout dark spine (24-30 mm. long) on upper edge 

 of arenla; central 1, stout and very bulbous at base, curved upward, reddish- 

 Mack , teretish, 2.5-5 cm. long, rarely wanting: flowers deep violet-purple, 

 i. S.fi cm. l.road: fruit ovate-globose, 2.5-3 cm. long, purplish-green, edible: 

 seed curved, deeply and irregularly pitted, 1.4 mm. long. Utah and Ari- 



::. Echinocereus gonacanthus Engelm. & Bigel. Rumph. in Forst. Hand. 

 ('act. Kd '_'. sor,. isxii. Ovate, 7. 5-12. 5 cm. high, simple or sparingly branched 

 ometimes <)), tuberculate, with large areolae 12-20 mm. apart: 

 it, angular, straight or variously curved and flexuous; radials S, 

 Hi LM mm. long, the rest 20-30 mm. long, lower and laterals quadran- 

 gular, yi-ll.iw at base an.l often dark-tipped, uppermost one much larger than 



