580 CACTACEAE 



4. E. pubispinus Engelm. Small, turbinate or ellipsoid, 5 cm. high, 2.5-3 

 cm. in diameter; ribs 13, compressed, tuberculate; spines velvety pubescent, in 

 age glabrate; radial spines 5-6 below, 9-12 above, 2-8 mm. long, straight to hooked; 

 central spines wanting or solitary, longer, 10-12 mm. long, strongly hooked. 

 Valleys: Utah. Son. 



5. E. cylindraceus Engelm. Globose to ovoid or ovate-cylindric, simple 

 or branching at the base, up to 9 dm. high and 3 dm. thick; ribs 13-27, obtuse and 

 tuberculate; spines stout, compressed, more or less curved, reddish; radials 

 about 12, 2.5-5 cm. long, the lowest stouter and hooked; centrals 4, very stout, 

 4-angled, about 5 cm. long, the uppermost broadest, straight and erect, the 

 lowest decurved; flowers yellow; fruit subglobose, pale green, 2.5 cm. thick. 

 Desert regions: Tex. — s Utah — Calif. — L. Calif. L. Son. 



6. E. Wislizeni Engelm. At first globose, at last cylindric, 5-12 dm. high; 

 ribs 21-25, or sometimes less, acute and oblique, more or less tubercled; radial 

 spines 1.5-5 cm. long, the 3 upper and 3-5 lower stouter, the lateral ones bristle- 

 like; centrals 4, stout, angled, red, 3.5-7.5 cm. long, the 3 upper straight, the 

 lowest and strongest up to 12 cm. long, fiat and hooked downwards; fiowers 

 yellow or sometimes red, 5-6.5 cm. long; fruit ovate, yeUow. Desert regions: 

 w Tex. — s Utah — Cahf . ; n Mex. L. So7i. 



7. E. subglaucus Rydb. Simple, depressed-globose or ellipsoid; ribs 8-13, 

 with conical tubercles; radial spines 8-9, white or with darker tips, straight, up 

 to 15 mm. long; central spines 1-3, curved, dark brown; flowers 3 cm. broad, 

 rose-red; fruit pear-shaped, 1 cm. high. E. glaucus K. Schimi., not Karw. 

 High table-land: Colo. Subnionl. 



8. E. Johnsoni Parry. Stem oval, 1-1.5 dm. high; ribs 17-21, rounded, 

 interrupted into low rounded tubercles; radial spines 10-14, 1.5-3 cm. long, the 

 upper strongest; central spines 4, stout, recurved, reddish gray, 3.5-4 cm. long; 

 flowers 5-6.5 cm. long, deep red to pink; seeds pitted. Arid regions: Utah. 

 Son. 



9. E. Sileri Engelm. Globose; ribs 13, prominent, densely crowded with 

 short rhombic-angled tubercles; radial spines 11-13, white; centrals 3, black with 

 pale base, 18 mm. long, the uppermost slightly longer; flowers scarcely 2.5 cm. 

 long, straw-colored. Desert regions: s Utah. L. Son. 



4. PEDIOCACTUS Britton & Rose. 



Stem globose, leafless, tubercled; the tubercles arranged in spiral rows, 

 ni])ple-shaped. Flowers borne on the tubercles, near the areolae. Hypanthium 

 funnelform, bearing a few scales. Petals numerous, pink. Stamens numerous. 

 Fruit globose, irregularly bursting, nearly or quite scaleless. Seed tubercled, 

 with a basal hilum. 



1. P. Simpsoni (Engelm.) Britton & Rose. Subglobose or turbinate at the 

 base, sometimes clustered, 7.5-12.5 cm. in diameter; ribs 8-13, with prominent 

 nipple-shaped tubercles, which are 12-16 mm. long; radial spines 20-30, slender, 

 straight, 8-12 mm. long; central spines 8-10, stouter, yellowish to black, 10-14 

 mm. long; flowers 16-20 mm. long, and nearly as broad, yellowish green or 

 ])urple; fruit green, 6-7 mm. long, suborbicular. Echinocacius Simpsoni Engelm. 

 Table-lands and plains: Nev. — Utah — Colo. Submont. — Subalp. 



5. CORYPHANTHA (Engehn.) Lem. 



Fleshy plants, with globular or oval, solitary or clustered stems, covered by 

 spirally arranged tubercles with spine-bearing areolae at the end. Leaves none, 

 ^'lowers borne near woolly areolae in the axils or near the base of the tubercles. 

 Hypanthium produced oeyond the ovary, campanulate or funnelform, naked. 

 Style filiform. Berry fleshy. [Mamillaria Haw. J 



Larger spines curved upwards; tubercles not grooved; flowers borne at the base of older 



tubercles, hence lateral on the stem. 1. C. Grahami. 



Spines all straight; tubercles grooved; flowers borne at the base of young tubercles, hence 

 nearly terminal. 



