CACTUS FAMILY 579 



7. E. goniacanthus (Engelm.) Lem. Stems ovoid, 7.5-12.5 cm. high, 

 simple or sparingly branched at the base; ribs 7, rarely 8 or 9, tuberculate ; spines 

 stout, angular, straight, or curved; radials 8, the lower 16-24 mm. long, the rest 

 2-3 cm. long, yellow at the base and dark-tipped, the upper one and the solitary 

 central one stout, 6-7-angled, 3-6 cm. long, 2 mm. broad; flowers scarlet, about 

 6mm. long. Cereus goniacanthus Engelm. Sandy hills: Colo. N.M. Submonl. 



8. E. paucispinus (Engelm.) Rumpl. Stem ovoid or ovoid-cylindric, 12- 

 25 cm. high, 5-10 cm. thick, simple or somewhat branched, deep green; ribs 

 5-7, tubercled; spines stout, with a bulbose base, straight or somewhat curved; 

 radials 3-7, reddish or dark, at last blackish, 18-32 mm. long; central one wanting 

 or rarely a stout subangular one, 3-4 cm. long, porrect; flowers purplish red, 

 2.5-3 cm. broad. Cereus paucispinus Engelm. Rocks and limestone hills: 

 Tex. Colo. N.M. Submont. 



3. ECHINOCACTUS Link & Otto. HEDGEHOG CACTUS, 

 BARREL CACTUS. 



Fleshy plants, with globular, or oblong, or sometimes cylindric stems, with 

 spine-bearing ribs, or these divided into spiral or vertical rows of tubercles. 

 Leaves none. Flowers borne just above young spine-bearing areolae, hence 

 appearing almost terminal on the stem. Hypanthium produced beyond the 

 ovary, more or less scaly, not spiny. Style columnar; stigmas slender. Fruit a 

 fleshy or dry berry, scaly. Seeds smooth, or nearly so, with an endosperm; 

 embryo curved. 



Stem with definite ridges, not tuberculate. 



Scales of the hypanthium subulate, copiously woolly in their axils; fruit dry and 



clothed with wool. 

 Uppermost central spine the broadest; ribs of the stem 1520. 



1. E. polycephalus. 



Lowermost central spine the broadest; ribs of the stem 13. 2. E. xeranthemoides. 

 Scales of the hypanthium ovate, orbicular, or cordate, not woolly in their axils; fruit 



not woolly. 

 One or more of the central spines strongly hooked, neither annulate nor strongly 



compressed. 

 Central spines except the hooked one, flattened, glabrous. 



3. E. Whipplei. 



Central spines all terete, pubescent. 4.' E. pubispinus. 



One or more of the central spines distinctly annular, strongly broadened, flattened 



above, slightly if at all hooked. 



Radial spines 9-13; upper central spine angled. 5. E. cylindraceus. 



Radial spines over 20; upper three spines terete. 6. E. Wislizeni. 



Stem with the ribs more or less divided into tubercles. 

 Tubercles terete. 



Radial spines 8-9; central ones 1-3; tubercles 1 cm. high. 7. E. subglaucus. 

 Radial spines 10-14; central spines 4; tubercles low. 8. E. Johnsoni. 



Tubercles rhombic in cross-section; radial spines 13-15. 9. E. Sileri. 



1. E. polycephalus Engelm. & Bigel. Globose to ovate or cylindric, 15-70 

 cm. high, 12.5-25 cm. in diameter, branched at the base; ribs 15-21; spines 

 8-15, very stout, compressed, more or less recurved, reddish; radials 4-11, com- 

 paratively slender, 2.5-5 cm. long; centrals 4, very unequal, 2-9 cm. long, the 

 uppermost broadest, curved upward, the lower longest and decurved; flowers 

 yellow; fruit globose, 15-20 mm. hi diameter. Stony or gravelly ground: Ariz. 

 Utah s Calif. L. Son. 



2. E. xeranthemoides Engelm. Stem globose, 2.5-12.5 cm. high; ribs 13, 

 sharp and interrupted; spines 10-15, straight or slightly curved; radials small, 

 about 3 cm. long; centrals 4, slender, 3-5 cm. long, the lowest broadest and por- 

 rect, otherwise as the preceding. Desert regions: s Utah Ariz. L. Son. 



3. E. Whipplei Engelm. Stem globose-ellipsoid, 7-13 cm. high, 5-10 cm. 

 thick; ribs 13-15, compressed and somewhat interrupted; radial spines 7-11, 

 white or the lower dusky, 12-36 mm. long; central spines 4, the uppermost 

 flattened, straight, 2.5-4 cm. long, 1-2.5 mm. broad at base, turned upwards, the 

 others 2.5-3 cm. long. 4-angled, dark brown, the lateral straight, the lowest sharply 

 hooked downward: flowers greenish red, 2-3 cm. long. Sandy soil: Utah Colo. 

 Ariz. Son. 



