WOOTON AND STANDLEY—FLORA OF NEW MEXICO. 451 
11. Mamillaria vivipara (Nutt.) Haw. Syn. Pl. Succ. Suppl. 72. 1819. 
Cactus viviparus Nutt. Fraser’s Cat. no. 22. 1813. 
Type Locauity: ‘‘Near the Mandan towns on the Missourie: lat, near 49°.”’ 
Rance: 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 necomericana 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. Bost. Journ. Nat. Hist. 6: 196. 1850. 
Type LocaLity: ‘‘Sterile, sandy soil on the Pierdenales,”’ Texas. 
Rance: 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 neomexicana Engelm. U. 8. & 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. 
Typr LocALiry: ‘‘From western Texas to New Mexico.” 
Ranae: New Mexico to western Texas and Mexico. 
New Mexico: Stinking Lake; Tucumcari; Mule Creek; near Black Rock; foot of 
Eagle Peak; San Antqnio; 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 centrals 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. Arizonica is somewhat stouter, with fewer but 
longer spines, radials 15 to 20, up to 20 mm. long, centrals 3 to 6, reddish brown above, 
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. ECHINOCACTUS 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 areole 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. 
