WOOTON AND STANDLEY—FLORA 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 Jonger 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: 261. 1856. 
TYPE LOcALITY: On the Pecos River, western Texas. 
Rance: 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 flat or sunken at the top, and may 
always be recognized by its pubescent, fine, white spines. 
3. Mamillaria grahami Engelm. Proc. Amer. Acad. 3: 262. 1856. 
Tyre Locauity: ‘“‘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; Mzngas Springs; 
Burro Mountains. Lower and Upper Sonoran zones. 
4. Mamillaria wrightii Engelm. Proc. Amer. Acad. 3: 262. 1856. 
Tyre Locauity: Near the Copper Mines, New Mexico. Type collected by Wright. 
Rance: 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 grahami 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.” 
Rance: 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 difficult to dig up because they 
have large, thickened, turbinate, sometimes branching roots. The tubercles are 
rather wide apart in well-grown plants and stand erect, with the short stout spines 
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 Miihlenpf. Allg. Gartenz. 16: 20. 1848. 
TYPE LOCALITY: Texas. 
Rance: Western Texas to southern Arizona and adjacent Mexico. 
New Mexico: Organ Mountains; Tortugas Mountain; Cooks Peak; Hillsboro; Stiens 
Pass; Mangas Springs Upper Sonoran Zone. 
52576°—15 29 
