OPUNTIA. 



139 



Type locality: Near Kerrville, Texas. 

 Distribution: Kerr County, Texas. 



Illustrations: Contr. U. S. Nat. Herb. 13: pi. 67; Plant World 19: 142. f. i; 143. f. 

 2, the last as 0. macrorhiza. 



Figure 175 is from a photograph of the type plant from near Kerrville, Texas. 



Fig. 175. — Opuntia mackensensii. 



1S56. 



137. Opuntia tenuispina Engelmann, Proc. Amer. Acad. 3: 294. 

 Opuntia minor C. Mueller in Walpers, Ann. Bot. 5: 50. 1858. 

 Low and spreading, but becoming 3 dm. high; joints obovate, attenuate at base, 7 to 15 cm. 

 long, light green ; leaves very slender, 4 mm. long or less; spines i to 3 from an areole, slender, usually 

 white but sometimes brownish, 3 to 5 cm. long, the upper spines erect or spreading; glochids brown; 

 flowers yellow, 6 to 7.5 cm. broad; ovary with numerous areoles filled with brown wool and brown 

 glochids; fruit oblong, 2.5 to 4 cm. long, with a deep umbilicus; seeds 4 ram. broad or less, very 

 irregular. 



Type locality: Sand hills near El Paso, Texas. 



Distribution: Southwestern Texas and adjacent parts of Mexico and New Mexico, 

 apparently extending to Arizona. 



Engelmann says that this plant grows with 0. phaeacantha, but is readily distinguished 

 from the latter by its spines and fruit. Cultivated plants and herbarium specimens closely 

 resemble 0. phaeacantha. 



Illustrations: Cact. Mex. Bound, pi. 75, f. 14; N. Mex. Agr. Exp. Sta. Bull. 78: pi. [15]. 



Plate xxiir, figure 3, represents a joint of the plant collected by Dr. Rose near El 

 Paso, Texas, in 1913. 



Series 11. PHAEACANTHAE. 



Bushy or depressed species, with relatively large, flat, persistent joints, the subulate, usually 

 stout spines brown at least at the base, or in some species nearly white. The series is composed of 

 about fifteen species, natives of the south central and southwestern United States, northern and 

 central Mexico. 



