WOOTON AND STANDLEY FLOEA OF NEW MEXICO. 441 



Fiirther critical study of the genus will undoubtedly result in the recognition of 

 many more species in this distribution area and in the better limitation of the species 

 now recognized. 



A specimen from Gallup, collected October 20, 1896, by Ashmun we are unable to 

 determine. Its spines suggest Opuntia cymockila, but the joints are orbicular or even 

 broader than long. 



1. Opuntia brachyarthra Engelm. & Bigel. Proc. Amer. Acad. 3: 302. 1856. 



Opuntia fragilis brachyarthra Coulter, Contr. U. S. Nat. Herb. 3: 440. 1896. 



Type locality: Inscription Rock, near Zuni, New Mexico. Type collected by 

 Bigelow in 1853. 



Range: Known only from the type locality. 



As described, this is a small tumid-jointed plant, possibly related to 0. arenaria or 

 0. fragilis. It has not been collected in recent years. A specimen from Santa Fe, 

 collected by Bigelow and referred to this species, may be Opuntia fragilis, as that 

 species comes into the mountains a short distance north of Santa Fe. Possibly Doctor 

 Coulter may have been right in considering Opuntia brachyarthra a subspecies of 

 0. fragilis. Until further material of 0. brachyarthra from the type locality can be 

 studied, it is probably better to retain it as a species. 



2. Opuntia fragilis (Nutt.) Haw. Syn. PI. Succ. Suppl. 82. 1819. 

 Cactus fragilis Nutt. Gen. PI. 1:296. 1818. 



Type locality: "From the Mandans to the mountains, in sterile but moist situ- 

 ations." 

 Range: Wisconsin and British Columbia to Kansas and northern New Mexico. 

 New Mexico: Lake La Jara; Tunitcha Mountains. Upper Sonoran Zone. 



3. Opuntia arenaria Engelm. Proc. Amer. Acad. 3: 301. 1856. 



Type locality: Sandy bottoms of the Rio Grande near El Paso, Texas or Chi- 

 huahua. 



Range: Southern New Mexico and western Texas. 



New Mexico: Mesquite Lake (Standley). Sandy soil, in the Lower Sonoran Zone. 



Coulter refers Fendler's 7, 150, and 153 to this species and to New Mexico. Where 

 they were obtained we have been unable to ascertain. Opuntia arenaria has such a 

 limited distribution in the type locality and occurs in a habitat so different from the 

 region about Santa Fe (where Fendler did most of his collecting) that we are inclined 

 to doubt the accuracy of the reference. It is possible the plant may occur in the 

 Rio Grande Valley west of Santa Fe, but even this is doubtful. The collection at 

 Mesquite Lake is the only one made since the type was gathered. The plants are 

 not at all abundant here. They grow on the dunes of pure sand about one of the lakes 

 or oxbows formed in the old bed of the Rio Grande. 



4. Opuntia stanlyi Engelm. in Emory, Mil. Reconn. 157./. 9. 1848. 



Type locality: On the Del Norte and Gila, New Mexico. Type collected by 

 Emory. 



Range: Southern New Mexico and Arizona and adjacent Mexico. 



New Mexico: Near Carlisle {Wooton). Lower Sonoran Zone. 



Opuntia stanlyi is a very distinct species with thick joints 10 to 12 cm. long and 

 3 to 4 cm. in diameter, with large tubercles and various spines. It forms beds often 

 2 or 3 meters across and only 30 cm. high or less. It grows on sandy mesas in the south- 

 western part of the State, but is more common in Arizona. Our specimens are from 

 very near the type locality. 



5. Opuntia grahami Engelm. Proc. Amer. Acad. 3: 304. 1856. 



Type locality: Sandy bottoms of the Rio Grande near El Paso, Texas or Chi- 

 huahua. V 



