WOOTON AND STANDEE Y FLOEA OP NEW MEXICO. 439 



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

 in each areole. 

 Joints bright green, rather strongly tub3rculate, 

 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. . irichophora. 



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 piu-plish, 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. 



I . 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, pon-ect, spreading; seeds 5 



' mm. in diameter 21. 0. phaeacantha. 



y ■ Joints prevailingly orbicular or ovate, the younger 



.V ones sometimes very broadly obovate, large, 



■ji; 20 to 30 cm. long, or even larger. 



^. Joints distinctly narrowed at the apex, ovate 



Vf or elliptic; spines large, divaricate, 3 to 5 



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



* brown at the base 22. 0. wootoni. 



'^ Joints mostly orbicular, sometimes broadly obo- 



vate; B'Dines various. 

 Spines few, on some joints none, yellow or 



brownish at the base, 1 to 2 cm. long 23. 0. dillei. 



