62 



THE CACTACEAE. 



Referred by Mrs. Brandegee (Erythea 5 : 122) to 0. nwlcsta Brandegee. It is closely 

 related to 0. molcsta, but its spines are different, though on the same general plan, and its 

 seeds are quite different. 



I'IGS. 74. 75, 76. Opuntia cholla. Xo.66. 



24. Opuntia versicolor Engelmann in Coulter, Contr. U. S. Nat. Herb. 3: 452. 1896. 

 Opunlia arborescciis versicolor E. Dams, Monatsschr. Kakteenk. 14: 3. 1904. 



Bush or tree-like, 2 to 4 meters high, with a large, open top sometimes 5 meters broad; trunk 

 and larger stems woody throughout, except the younger branches; terminal joints 10 to 20 cm. 

 long, 2.5 cm. in diameter, variously colored, not strongly tuberculate when living; tubercles 1.5 

 cm. long; spines 5 to n, 5 to 25 mm. long, dark colored, with close-fitting sheaths; glochids red- 

 dish brown; flowers variously colored, yellow, greenish, reddish, or brown, 3 to 5.5 cm. broad; 

 ovary tuberculate, with large areoles bearing wool, glochids, and long deciduous bristles; fruit 

 persisting for months, sometimes for a year, 2.5 to 4 cm. long, at first somewhat tuberculate, becom- 

 ing pear-shaped or globose, sometimes proliferous; seeds white, 5 mm. broad. 



Type locality: Tucson, Arizona. 



Distribution: Arizona and northern Mexico. 



This species is common on the lower foothills and is only rarely found on the mesas. 

 It is of slow growth, propagating almost entirely from seed. As the name suggests, it has 

 flowers of many colors ; each plant has its own color and the color of the flowers is to a 

 greater or less extent paralleled in that of the branches. The contrast in color shown by 

 a colony of these plants is very striking and one's first impression is that more than one 

 species exists. 



Named specimens of this species were distributed by the late Dr. C. G. Pringle in 

 1 88 1, but the species was not published until 1896. 



Illustrations: Ariz. Agr. Exp. Sta. Bull. 67: pi. 6, f. i; Bull. Torrey Club 32: pi. 9, f. 

 4 to 8; Hornaday, Camp-fires on Desert and Lava, pi. facing p. 18, 116, 320; N. Mex. Agr. 

 Exp. Sta. Bull. 60 : pi. 6, f. i ; Plant World n in : f. 8; Sargent, Man. Trees N. Amer. f. 561. 



Plate vii, figure 5, represents a fruiting joint; plate vin, figure 2, is from a photo- 

 graph taken by Dr. MacDougal near the base of the Santa Catalina Mountains, Arizona ; 

 plate ix, figures 2 to 5, are paintings made at the Desert Laboratory, Tucson, Ari- 

 zona, by Kako Morita, showing the range in color of the flowers. 



