WOOTON AND STANDLEY FLOBA OF NEW MEXICO. 449 



This little plant is rather interesting and is prized as somewhat of a rarity by cactus 

 growers. The flat or sunken top, the numerous fine, smooth, white spines, at the top 

 much longer and spirally arranged, and the small size make the plant easily recogniz- 

 able. Its habit of producing the clavate, few-seeded, red fruit several months after 

 flowering is a striking peculiarity. 



2. Mamillaria lasiacantha Engelm. Proc. Amer. Acad. 3: 2G1. 1856. 

 Type locality: On the Pecos River, western Texas. 



Range: Western Texas and southern New Mexico and Arizona; also in adjacent 

 Mexico. 



New Mexico: Mouth of Dark Canyon, Guadalupe Mountains ( Wooton). Dry lime- 

 stone hills, in the Upper Sonoran Zone. 



This superficially resembles the preceding to such an extent that a careless observer 

 may mistake it for that species. But it is never fiat or sunken at the top, and may 

 always be recognized by its pubescent, fine, white spines. 



3. Mamillaria graharni Engelm. Proc. Amer. Acad. 3: 262. 1856. 



Type locality: "Mountainous regions from El Paso, southward and westward," 

 Chihuahua. 



Range: Utah to western Texas, southern California, and northern Mexico. 



New Mexico: Tortugas Mountain; mountains east of Dona Ana; Mangas Springs; 

 Burro Mountains. Lower and Upper Sonoran zones. 



4. Mamillaria wrightii Engelm. Proc. Amer. Acad. 3: 262. 1856. 



Type locality: Near the Copper Mines, New Mexico. Type collected by Wright. 



Range: Western Texas, New Mexico, and adjacent Mexico. 



New Mexico: Mangas Springs; Burro Mountains; White Oaks. Upper Sonoran 

 Zone. 



Pressed material of this species is hard to distinguish from the preceding, but the 

 characters given in the key will hold. Growing plants are more easily distinguishable. 

 Mamillaria graharni is usually so thickly covered with fine white radials that it is 

 difficult to see the tubercles, and the hooked central spines are reddish brown; while 

 in M. wrightii the plants appear green because of the fewer radials and the almost 

 black, hooked centrals are noticeably more numerous. 



5. Mamillaria meiacantha Engelm. Proc. Amer. Acad. 3: 263. 1856. 

 Type locality: 'Western Texas and New Mexico." 



Range: Mountains of western Texas, southern New Mexico, and northern Chi- 

 huahua. 



New Mexico: Queen. Upper Sonoran Zone. 



This species and the next are easily separated from all other Mamillarias l>y the 

 shape of the plant, this appearing as a flat-topped disk of -piny tubercles at ma I only 

 a few centimeters above the surface of the soil and often about flush with it. Often 

 the plants occur La aey ices of the rocks and surrounded by grassee and otto c pi int 

 in such a way as to be easily overlooked. They are difficult to dig up because they 

 have large, thickened, turbinate, sometimes branching root,-. The I 

 rather wide apart in well-grown plants and stand erect, with the Bhortstoul I 

 Burmounting them. The flowers are small and inconspicuous, bul the frail 

 brighl red. 'I he pine characters given in the key will separate the two Bpt 



6. Mamillaria heyderi Miihlenpf. All-. Gartenz. 10: 20. L848. 

 T\ pb i ■>' \i 1 1 v : Tea 



. We tern Texas to southern Arizona and adjacent M 

 N ; i \>. M i sico: < >rgan Mountain ; Tortugas Mountain; l taok Peak; Hillaboro;8tienfl 

 Pass; Mangas Spring I pper Sonoran Zone. 

 52576*— 15 29 



