244 CACTACE^E. Mamillaria. 



Common on sandy or gravelly soil or among rocks about San Diego (Parry, Aqassiz, Hitchcock), 

 and on the neighboring islands, and southward through the Peninsula, W. Gabb. From 2 or 3 

 to 6 or 7 inches high, 1 to 1| thick ; tubercles 2J to 3 lines long ; radial spines 2| to 5, and cen- 

 tral ones 5 to 7 lines long ; flowers 9 to 12 lines in diameter, dirty yellowish tinged with red. 



2. M. G-rahami, Engelm. Similar to the last : smaller, with smaller less closely 

 pitted seeds, but longer and more numerous (15 to 30) spines, and without axillary 

 bristles. Cact. Mex. Bound. 7, t. 6, fig. 1-8. 



Common on the most rugged rocks on both sides of the Colorado (Schott, Newberry), and east- 

 ward into New Mexico. Heads 1 to 3 inches high, 1 to 1^ thick. 



3. M. phellosperma, Engelm. Ovate to cylindrical, usually simple : tubercles 

 long-oval, with wool and bristles in their axils, and 30 to 60 spines at the apex, in 



2 or 3 series ; the outer thinner and paler ; the inner stouter and often darker ; the 



3 or 4 central spines stouter, dark brown, and one or several hooked : flowers with 

 ciliate sepals and 12 to 13 acuminate petals : stigmas 5 : berry obovate or clavate, 

 crimson, containing rather few large globose reticulated and warty brown seeds, with 

 a large spongy appendage. Cact. Mex. Bound. 6, t. 7. 



From the eastern slope of the mountains near San Felipe to the Mohave country, and through- 

 out Western Arizona. Heads 2 to 5 inches high, 1 J to 2 inches thick ; tubercles 4 to 7 lines long, 

 not as much crowded as in the last two species, but with a much larger number of spines, 4 to 9 

 lines in length ; flower dirty yellowish red, about an inch wide. The seed is partially imbedded in 

 a curious spongy mass, an aril-like enlargement of the funiculus. 



2. Flowers larger, vertical, from the base of a groove on the young or nascent 



tubercles. CORYPHANTHA. 



4. M. Arizonica, Engelm. n. sp. Globose or ovate ; tubercles long-cylindrical, 

 ascending, deeply grooved, bearing numerous straight rigid spines: the 15 to 20 

 exterior spines whitish ; the 3 to 6 interior ones stouter, deep brown above : flowers 

 large, rose-colored : sepals 30 to 40, linear-subulate, fimbriate : petals 40 to 50, 

 lance-linear, awned: stigmas 8 to 10, white: berry oval, green, with obovate com- 

 pressed pitted light brown seeds. 



On sandy and rocky soil in Northern Arizona, from the Colorado eastward (Cones, Palmer, F. 

 JBischqff), and into Southern Utah (J. E. Johnson) ; probably in Southeastern California. Larger 

 in all its parts than the foregoing species ; 3 or 4 inches thick ; tubercles an inch long ; spines 5 

 to 15 lines long ; flowers 2 to 2J inches wide, very showy. 



2. ECHINOCACTUS, Link & Otto. 



Flowers about as long as wide. Ovary covered with sepaloid scales, naked or 

 woolly in their axils. Fruit succulent or sometimes dry, covered with the persistent 

 calyx-scales, sometimes enveloped in copious wool, and usually crowned with the 

 persistent remnants of the flower. Seed obliquely obovate, black. Embryo curved 

 over the small albumen ; cotyledons parallel to the sides of the seed. Mostly 

 larger, sometimes gigantic, globose or depressed, or ovate, or rarely subcylindric, 

 simple or very rarely cespitose ; bunches of spines on the more or less vertical ribs. 

 Flowers contiguous to and above the spines, on the latest growth of the plant, often 

 from the nascent woolly areolse and therefore more or less vertical, open only in 

 sunlight. 



* /Scales of the ovary ovate, orbicular, or cordate, and mostly fringed, their axils 

 almost naked : fruit scaly, never woolly. Leiocarpi. 



-f- Spines smooth. 



1. E. Whipplei, Engelm. & Big. Heads solitary, globose or ovate, middle-sized, 

 with 13 (to 15) compressed and interrupted ribs : of the 7 to 11 outer and 4 inner 

 spines, the ivory-white upper ones are the longest and broadest and recurved or 



