454 CONTEIBUTIONS FEOM THE NATIONAL HEEBAEIUM. 



or more acute ridges. The spines are few, 6 to 9 in the areole, stout, straight or some- 

 what curved, compressed, bony or horny, reddish, with a single recurved central, 

 this not hooked. The flowers are moderately large, about 5 cm. long, bright pink, 

 fading as they grow older, white-woolly outside. They are followed by a pulpy, 

 bright red fruit which persists for some time, unless eaten by birds or small rodents. 



4. ECHINOCEREUS Engelm. 



Plants globose to cylindric (ours all erect and stout), solitary, proliferous or cespi- 

 tose, ribbed, 5 to 60 cm. high, usually less than 30 cm.; areoles usually approximate, 

 often with the spines overlapping and almost concealing the stem; flowers borne close 

 above old spine-bearing areolae, thus lateral on the stem ; ovary spiny but the spines 

 deciduous from the ripe fruit; fruit succulent, with thin rind, edible, with a pleasant 

 flavor in most species; seeds small, numerous. 



KEY TO THE SPECIES. 



Flowers small, about 2 cm. long, green; spines reddish and white. 

 Radial spines long, 5 to 10 mm. ; centrals 3 to 6, the lower one 

 about 25 mm. long, somewhat reflexed; i^lants conic at 



the apex 1 . E. chloranthiis. 



Radials short, 2 to 6 mm. long, rigid, pectinate; centrals 

 mostly wanting, occasionally a few about 25 mm. long; 



plants depressed at the apex 2. E. viridiflorus. 



Flowers larger, 3 to 10 cm. long, not gi'een; spines variously 

 colored. 

 Flowers bright yellow, large, about 10 cm. long, closing at 

 night; spines short, pectinate, more or less tinged with 



pink 3. E. dasyacanthus. 



Flowers never yellow; flowers and spines various. 



Flowers large, 7 to 10 cm. long, open only in daylight, 

 purple or rose, never scarlet; petals mostly acute. 

 Spines short, rigid, pectinate; centrals mostly want- 

 ing; flowers purple to rose. 

 Flowers piu-ple; spines white; plants small, 5 to 



8 cm. high 4. E. pectinatus. 



Flowers rose to red; spines variegated red and 



white; plants larger, 10 to 20 cm. high.. 5. E. rigidissimus. 

 Spines longer, not pectinate; centrals long and con- 

 spicuous; flowers pm^le. 

 Spines dark, comparatively few, the upper cen- 

 trals conni vent-curved; stems only a few 



together or solitary 6. E. fendleri. 



Spines pale yellow to straw-colored, very num- 

 erous and long; young spines straight, 

 dusky; plants usually forming large 

 mounds, often a meter across or more. . . 7. E. stramineus. 

 Flowers of medium size, 3 to 7 cm. long (rarely a little 

 larger), open day and night, bright scarlet, orange 

 scarlet, or cardinal, never purple; petals mostly 

 obtuse. 

 Spines very stout, strongly angled, relatively few in 

 the areole. 

 Spines 6 to 8, mostly 6, twisted and curved; 

 radials 2 to 3 cm. long; centrals 4 cm. 

 long or more 8. E. gonacanthus. 



