WOOTON AND STANDLEY FLOEA OF NEW MEXICO. 439 



Spines 2 to 5 cm. long, less numerous, 1 to 5 large ones 

 in each areole. 

 Joints bright green, rather strongly tub^rculate, 

 wrinkled; spines few, in the upper areoles, 

 about 2 cm. long, slender, white; lower part 

 of the joints almost naked; fruit spherical. . .14. 0. sphaerocarpa. 

 Joints paler, mostly obscured by the spines, not 

 noticeably tuberculate nor wrinkled when 

 dry; spines mostly covering the joints, the 

 largest 4 to 5 cm. long, stouter, yellowish or 

 brown-tinged; fruit longer than broad. 

 Lower spines hairlike, especially on the older 



joints 15. 0. trichophora. 



Lower spines not hairlike 16. 0. polyacantha. 



Fruit succulent, a thick, rather tough rind surrounding the 



pulpy interior, red or purple when ripe; joints mostly 



larger (small in two species); spines and habit various. 



Plants erect or suberect, often 1 meter high or more, 



the branches often decumbent at the base, but at 



least 3 or 4 joints high. 



Spines pale yellow, uniform in color throughout, 1 to 



2 cm. long, 3 to 5 in each areole, appressed- 



reflexed; stems with a noticeable though short 



trunk 17. 0. chlorotica. 



Spines not as described above; trunklike stem always 



wanting (except in very young plants). 



Joints mostly reddish or purplish, or bluish green 



and glaucous, very thin, at least some of them 



armed with long, dark brown or black spines 



4 to 8 cm. long 18. 0. macrocentra. 



Joints never reddish, mostly yellowish green, thick; 

 spines brown, yellow, white, or variegated. 

 Joints prevailingly obovate, of medium size, the 

 younger 10 to 18 cm. long, the older some- 

 times larger. 

 Spines few, short, mostly white or yellow, some- 

 what reflexed; seeds small, about 3 mm. in 

 diameter. 



Spines white 19. 0. dulcis. 



Spines clear bright yellow 20. 0. lindheimeri. 



Spines more numerous, darker colored in the 

 typical form, the young spines dark brown, 

 3 to 5 cm. long, porrect, spreading; seeds 5 



mm. in diameter 21. 0. phaeacaniha. 



Joints prevailingly orbicular oi ovate, the younger 



inns sometimes very broadly obovate, large, 



20 to 30 cm . long, or even larger. 



Joints distinctly narrowed at the apex, ovate 



or elliptic; spines large, divaricate, 3 to 5 



cm. long, stout, yellow at the apex, reddish 



brown at the base 22. O. wootoni. 



Joints mostly orbicular, sometimes broadly obo- 

 vate; spines various. 

 Spines few, on Borne joints none, yellow or 



brownish al the base, l to 2 cm. long 23. 0. dilhi. 



