WOOTON AND STANDLEY FLOEA 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, srriooth, white spines, at the top 

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

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

 flowering is a striking peculiarity, 



2. Maraillaria lasiacantha Engelm. Proc. Amer. Acad. 3: 261. 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 {Woolon). 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 flat or sunken at the toj5, and may 

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



3. Maraillaria graharoi 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; Mcngas Springs; 

 Burro Mountains. Lower and Upper Sonoran zones. 



4. Maraillaria 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 distinguioha^ble. 

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

 difiicult 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 raeiacantha 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 by the 

 shape of the plant, this appearing as a flat-topped disk of spiny tubercles at most only 

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

 the plants occur in crevices of the rocks and surrounded by grasses and other plants 

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

 have large, thickened, turbinate, sometimes branching roots. The tubercles are 

 rather wide apart in well-grown jilants and stand erect, with the short stout sjiinea 

 surmounting them. The flowers are small and inconspicuous, but the fruits are 

 bright red. The spine characters given in the key will separate the two species. 



6. Mamillaria heyderi Muhlenpf. Allg. Gartenz. 16: 20. 1848. 

 Type locality: Texas. 



Range: Western Texas to southern Arizona and adjacent Mexico. 

 New Mexico: Organ Mountains; Tortugas Mountain; Cooks Peak; Hill8boro;Stien3 

 Pass; Mangas Springs Upper Sonoran Zone. 

 52576°— 15 29 



