WOOTON AND STANDLEY FLORA OF NEW MEXICO. 451 



11. Mamillaria vivipara (Nutt.) Haw. Syn. PI. Succ. Suppl. 72. 1819. 

 Cactus viviparus Nutt. Eraser's Cat. no. 22. 1813. 



Type locality: "Near the Mandan towns on the Missourie: lat. near 49°." 



Range: British America to Montana, Nebraska, Utah, and northern New Mexico. 



New Mexico: Chusca Mountains; Tierra Amarilla. Plains. 



It is difficult to separate this species from Mamillaria radiosa and its subspecies, 

 but, generally speaking, the plants referred to M. vivipara have the more northerly 

 range, are smaller and cespitose, and have fewer, shorter, and more slender spines, 

 though the differences seem to be of degree rather than kind. 



Mamillaria vivipara is very rare in the State, only two collections of it being on 

 record, but it is to be expected in the mountains or on the high plains in the northern 

 part. Mamillaria radiosa and its subspecies neomexicana are common almost every- 

 where above 1,500 meters throughout the State and it is altogether probable that 

 the subspecies arizonica occurs along the southwestern border. 



12. Mamillaria radiosa Engelm. Boat. Joum. Nat. Hist. 6: 196. 1850. 

 Type locality: "Sterile, sandy soil on the Pierdenales," Texas. 



Range: Colorado and New Mexico to western Texas and northeastern Mexico. 



New Mexico: Pecos; head of the Rio Mimbres; Lake Valley; Nara Visa; Tierra 

 Amarilla; Mogollon Creek; Sierra Grande; Farmington; Santa Fe; Raton. Upper 

 Sonoran and Transition zones. 



12a. Mamillaria radiosa neom.exicana Engelm. U. S. & Mex. Bound. Bot. Cact. 



64. 1859. 



Mamillaria vivipara radiosa neomexicana Engelm. Proc. Amer. Acad. 3: 269. 1856. 



Mamillaria neomexicana A. Nels. in Coulter, New Man. Rocky Mount. 327. 1909. 



Type locality: "From western Texas to New Mexico." 



Range: New Mexico to western Texas and Mexico. 



New Mexico: Stinking Lake; Tucumcari; Mule Creek; near Black Rock; foot of 

 Eagle Peak; San Antonio; Burro Mountains; Gallup; Mangas Springs; Inscription 

 Rock; Santa Fe; Magdalena Mountains; Sandia Mountains; Cooks Peak. Upper 

 Sonoran Zone. 



This is with difficulty distinguishable from the species or from subspecies arizonica. 

 Those forms with 20 to 30 radials 6 to 8 mm. long and 4 or 5 centi-als of about the same 

 length not pronouncedly purplish or reddish brown, on tubercles 8 to 12 mm. long, 

 are referred to M. radiosa. Neomexicana has more numerous radials, 14 to 40, and 

 centrals mostly 6 to 9 (3 to 12), slightly larger tubercles, and longer spines, the cen- 

 trals purplish, especially with age. Aiizonica is somewhat stouter, with fewer but 

 longer spines, radials 15 to 20, up to 20 mm. long, centrals 3 to 6, reddish brown a bove, 

 and tubercles 12 to 25 mm. long; its flowers, also, are considerably larger. In the 

 present state of our knowledge, it is most convenient to recognize these as forms of 

 a single species, perhaps the commonest Mamillaria in the State. 



3. ECHINOC ACTUS Link & Otto. 



Globose or short-cyLindric plants, mostly solitary, with tubercles coalescing into 

 vertical or spirally twisted ridges bearing clusters of mostly stout, more or less flat- 

 tened, curved or sometimes hooked spines; flower-bearing areolae above the young 

 spine-bearing ones, the plants thus blooming in the center at the top; ovary scaly 

 or woolly, not spiny; fruit dry or succulent, scaly or smooth. 



