160 CACTACEAE 



long, white, or slightly tipped with black, closely interlocking-spreading, nearly concealing the 

 stem; central spines much stouter, 10-14, unequal, 1-2.5 cm. long, divaricately spreading, white 

 to ash-yellow at the base, shading through deep maroon to black from about the middle toward 

 the tips; flowers 2.5-3 cm. long, about 1.5 cm. broad when expanded; perianth-segments with 

 rose-colored midveins, shading into light purple toward the margins; outer perianth-segments 

 ciliate-margined ; style and stigma-lobes white ; fruit clavate, green, naked or nearly so ; seeds 

 brown, minutely tuberculate. 



Infrequent on rocky mesas and in desert mountain canyons, Lower _ Sonoran Zone; Morongo Valley to 

 Indio and in the mountains between the Mojave and Colorado Deserts, California. May. 



2. Coryphantha deserti (Engelm.) Britt. & Rose. Yellow Foxtail Cactus. 



Fig. 3338. 



Mammillaria deserti 'Engelm. Bot. Calif. 2: 449. 1880. 



Cactus radiosus var. deserti J. M. Coult. Contr. U.S. Nat. Herb. 3: 121. 1894. 

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

 Coryphantha deserti Britt. & Rose, Cactaceae 4: 46. 1923, in part. 



Simple or very rarely 1-3-branched, globose, ovoid to short-cylindric plant 5-25 cm. high, 

 6-9 cm. in diameter, densely covered with interlocking spines. Areoles slender, 8-12 mm. long; 

 radial spines 20-25 (30), acicular, unequal, 9-16 mm. long, spreading, white or ash-gray, black- 

 tipped; central spines 2-4, stout, terete, 5-15 mm. long, somewhat spreading, those at top of 

 plant black or blue-black on the upper half, fading through red to white at the base, the whole 

 spine light at base of old plants; flowers straw-colored, tipped with pink or rose, 2.5-3 cm. wide 

 when expanded, outer perianth-segments ciliate; fruit oblong; seeds obliquely obovate, curved, 

 minutely pitted. 



Infrequent on rocky hillsides and mesas. Lower Sonoran Zone; Inyo County to the southern edge of the 

 Mojave Desert in eastern San Bernardino County, eastward to Utah. May. 



3. Coryphantha arizonica (Engelm.) Britt. & Rose. Arizona Foxtail Cactus. 



Fig. 3339. 



Mammillaria arizonica Engelm. Bot. Calif. 1: 124. 1876. 



Cactus radiosus var. arizonica J. M. Coult. Contr. U.S. Nat. Herb. 3: 121. 1894. 

 Mammillaria radiosa var. arizonica Sebum. Gesamtb. Kakteenk. 481. 1898. 

 Coryphantha arizonica Britt. & Rose, Cactaceae 4: 45. 1923. 



Solitary or in age forming cespitose clumps up to 1 m. wide, each head globose to ovoid, 6-10 

 cm. in diameter. Tubercles large, 2-2.5 cm. long, cylindric, often slightly curved upward, the 

 groove deep ; radial spines 12-20, acicular, rigid, unequal, 1-3 cm. long, spreading but scarcely 

 interlocking, white or ashy ; central spines 2-6, stouter, deep brown on upper part, whitish at the 

 base, 1-2 . 5 cm. long ; flowers 5-7 cm. broad, pink to rose ; outer perianth-segments _ linear- 

 subulate, the margins fimbriate ; inner perianth-segments alternately linear-lanceolate ; fruit oval ; 

 seeds compressed, pitted. 



On rocky mesas and desert mountain canyons. Lower Sonoran Zone; from eastern San Bernardino County 

 in the vicinity of Cima and Goff eastward into northern Arizona, southern Nevada, and possibly southern Utah. 

 May. 



11. PHELLOSPERMA Britt. & Rose, Cactaceae 4: 60. 1923. 



A solitary or few-branched cespitose cactus w^ith globose to cylindrical stems and 

 large fleshy, simple or branched roots. Tubercles terete, not grooved, naked in the axils. 

 Flowers axillary to older tubercles, funnel form. Fruit obovate to narrowly clavate, bright 

 red. Seeds dull black, rugulose, embedded in a thick corky base nearly as large as the 

 seed proper. [Name Greek, referring to the corky base of the seed.] 



A monotypic genus of the southwestern United States and adjacent Mexico. Type species, Mammillaria 

 tetrancistra Engelm. 



1. Phellosperma tetrancistra (Engelm.) Britt. & Rose. Yaqui Cactus. Fig. 3340. 



Mammillaria tetrancistra Engelm. Amer. Journ. Sci. II. 14: 337. 1852. 

 Mammillaria Phellosperma Engelm. Proc. Amer. Acad. 3:262. 1856. 

 Cactus Phellosperma Kuntze, Rev. Gen. PI. 1: 261. 1891. 

 Cactus tetrancistrus J. M. Coult. Contr. U.S. Nat. Herb. 3: 104. 1894. 

 Phellosperma tetrancistra Britt. & Rose, Cactaceae 4: 60. 1923. 



Stems oblong to cylindrical, 5-35 cm. high, densely spiny ; root carrot-like or branched. 

 Tubercles commonly elongated; radial spines 30-60, acicular, white or slightly darkened toward 

 the tip, spreading, forming a dense white covering; central spines 4 (rarely only 1), from 1 to 

 all of them hooked, 1-2.5 cm. long; flowers 2.5—3.5 cm. long, rose, orchid, or light purple; tube 

 naked, slender, greenish at the base ; scales at apex of tube and outer perianth-segments ciliate- 

 margined; style and stigma-lobes cream-colored; fruit 1.5-3.5 cm. long, depressed-umbilicate 

 at the apex; seeds 1.8-2.2 mm. in diameter. 



_ Gravelly or stony slopes and mesas, Lower Sonoran Zone; southern Nevada and Utah to northern Lower 

 California and western Arizona. April. 



