CACTUS FAMILY 159 



1. Sclerocactus polyancistrus (Engelm. & Bigelow) Britt, & Rose. Mojave 



Bisnaga. Fig. 3335. 



Echinocactus polyancistrus Engelm. & Bigelow in Engelm. Proc. Amer. Acad. 3: 272. 1856. 

 Sclerocactus polyancistrus Britt. & Rose, Cactaceae 3: 213. 1922. 



Simple globose to oblong plant up to 4 dm. high. Ribs 12-17, obtuse, 1-1.5 cm. high, strongly- 

 undulate; radial spines 15-20, terete, 1-2.5 cm. long; hooked central spines 6-8, 3-6 cm. long, 

 spreading, borne on the lower two-thirds of the areole, the upper third bearing 2-4 (usually 3) 

 flattened, erect, white spines 4-12 cm. long; flowers magenta, 4-6 cm. long; inner perianth- 

 segments oblong, 3-4 cm. long ; tube 2-3 mm. long ; stamens numerous, half as long as the peri- 

 anth ; style 1-1.5 cm. longer than the stamens; stigma-lobes greenish; fruit becoming dry, nearly 

 scaleiess, 3-i cm. long ; seeds black, 4 mm. long, hilum sublateral. 



Occasional on gravelly slopes and mesas, Lower Sonoran Zone; Mojave Desert, California, into southern 

 Nevada and Utah, and northwestern Arizona. May. 



9. PEDIOCACTUS Britt. & Rose in Britt. & Brown, 111. Fl. ed. 2. 2: 569. 1913. 



Small globose, single or cespitose leafless cactus with large tubercles borne on 8-13 

 low spiraled ribs. Areoles woolly when young, becoming naked. Flowers broadly cam- 

 panulate, with a very short tube, pink, borne just to one side of the areole at the apex of 

 a tubercle, the outer perianth-segments shorter than the inner; inner perianth-segments 

 oblong, acute to mucronate ; axils of scales on the tube naked. Stamens numerous. Ovary 

 globose, green. Fruit dry, greenish, dehiscing irregularly along the side._ Seeds black, 

 tuberculate, keeled on the back ; hilum subbasal, large. [Name Greek, meaning plains and 

 cactus.] 



A monotypic genus of western United States. Type species, Echinocactus Simpsonii Engelm. 



1. Pediocactus Simpsonii (Engelm.) Britt. & Rose. Hedgehog-thistle. Fig. 3336. 



Echinocactus Simpsonii Engelm. Trans. St. Louis Acad. 2: 197. 1863. 



Echinocactus Simpsonii var. minor Engelm. loc. cit. 



Mammillaria Simpsonii M. E. Jones, Zoe 3: 302. 1893. 



Mammillaria Purpusii Schum. Moiiatss. Kakteenk. 4: 165. 1894. 



Echinocactus Simpsonii var. robustior J. M. Coult. Contr. U.S. Nat. Herb. 3: 377. 1896. 



Pediocactus Simpsonii Britt. & Rose in Britt. & Brown, 111. Fl. ed. 2. 2: 570. 1913. 



Plants depressed-globose, turbinate at the base, 15-25 cm. in diameter, with strong, con- 

 tiguous ovoid tubercles 1.5-2 cm. long. Radial spines 10-15, white, acicular, spreadmg hori- 

 zontally, 10-25 mm. long ; central spines 8-12, stouter and longer than the radials, 1-3 cm. long, 

 white to yellowish at the base, reddish brown to nearly black toward the tips, erect-spreadmg; 

 flowers 2-3.5 cm. long, crowded in the center of the plant, surrounded by white to brownish 

 wool; outer perianth-segments obtuse, serrulate; inner perianth-segments linear-oblong, acute; 

 filaments, style and stigma-lobes yellow, fruit 6-8 mm. in diameter; seeds asymmetrically obo- 

 vate, 3 mm. long. 



In dry interior mountain valleys and rocky ridges, timberless Arid Transition and Upper Sonoran Zones; 

 central Washington to Nevada. April-May. 



10. CORYPHAnTHA (Engelm.) Lemaire, Cactees 32. 1868. 



Solitary or cespitose plants with globose to cylindric stems bearing conspicuous, 

 spirally arranged tubercles. Tubercles mammillate, narrowly grooved from apex to base 

 when mature. Flowers borne near the top of the plant in the axils of young tubercles, 

 comparatively large and showy ; perianth-segments withering-persistent._ Ovary naked or 

 sparsely scaly in some species. Fruit ovoid to oblong, greenish to yellowish. Seeds brown 

 (or black), smooth to finely reticulate; hilum subbasal; embryo curved. [Name Greek, 

 referring to the apical position of the flowers.] 



A genus of 40-50 species from the southern United States to central Mexico (one species ranging north to 

 southern Canada). Type species, Mammillaria sulcolanata Lemaire. 



Central spines 12-14; tubercles broad, less than 1 cm. long. 1- C. Alversontt. 



Central spines 2-6; tubercles slender, 12-25 mm. long. 



Tubercles 12-15 mm. long; flowers straw-colored, or tinged with rose or purple toward the tips 3 cm. 



broad; radial spines 20-25. 2. C. desertu 



Tubercles 20-25 mm. long; flowers rose to purple, 5-7 cm. broad; radial spines 15-20. 3. C. amontca. 



1. Coryphantha Alversonii (J. M. Coult.) Orcutt. Foxtail Cactus. Fig. 3337. 



Cactus radiosus var. Alversonii J. M. Coult. Contr. U.S. Nat. Herb. 3: 122. 1894. 

 Mammillaria Alversonii Zeiss. Monatss. Kakteenk. 5: 70. 1895. 

 Mammillaria radiosa var. Alversonii Schum. Gesamtb. Kakteenk. 481. 1898. 

 Coryphantha Alversonii Orcutt, Cactography 3. 1926. 



Stems simple, or infrequently 1-2-branched at the base, oblong to short-cylindric, 1-2 dm. 

 high, 5-8 (10) cm. in diameter. Tubercles short and thick; radial spines 20-3:), acicular, 1-/ cm. 



