WOOTON AND STANDLEY—FLORA 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 tub2rculate, 
wrinkled; svines few, in the upper areoles, 
about 2 cm. long, slender, white; lower part 
of the joints almost naked; fruit spherical. ..14. O. 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. 
joints. ...-.2.... 2202 e eee ee eee 15. O. trichophora. 
Lower spines not hairlike.......-.-.----+----- 16. O. 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.....-- 22 eee eee eee eer ececeee 17. O. 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 em. long. .....------ eee eee eee ee ee eee 18. O. 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. O. dulcis. 
Spines clear bright yellow..........-.------20. O. lindhetmeri. 
Spines more numerous, darker colored in the 
typical form, the young spines dark brown, 
3 to5 cm. long, porrect, spreading; seeds 5 
mm. in diameter........ wee ence eee eens 21. O. phaeacantha. 
Joints prevailingly orbicular or ovate, the younger 
ones 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. wootons. 
Joints mostly orbicular, sometimes broadly obo- 
vate; spines various. 
Spines few, on some joints none, yellow or 
brownish at the base, 1 to 2 cm. long....23. O. dillei. 
