©4 MISSOURI BOTANICAL GARDEN. 



The species differs from Opuntia Engelmanni, to which it 

 is most closely related, especially in habit, and in nature of 

 spines and fruit. No. 9560 D. G. is considered to be the same, 

 although its spicules arc yellow and its spines much lighter in 

 color. The color of spines and spicules, while of value in tax- 

 onomy, can not be used to differentiate species unless accom- 

 panied by other characters. There are a score or more of 

 species which have both yellow and brown or reddish-brown 

 spicules. 



The type is No. 9559 D. G., collected near Kirkland, Arizona, 

 September 8, 1908. The description was drawn in the field 

 beside the brown spiculed form. — Plates 10; 2, f. 8; 13, f. 8. 



Opuntia subarmata sp. no v. 



Plant tall, rather compactly branched, erect or ascending, making a 

 shrub 12 to 15 dm. high and 18 or more dm. in diameter; joints broadly 

 oval to obovate, commonly 17 to 25 cm. in diameter, broadly to narrowly 

 rounded above, blue glaucous green changing through yellowish to brown- 

 ish and finally gray scaly; areoles elliptical to ovate or even subcircular, 3 

 to 6 mm. in longest diameter, 3.5 to 4.5 cm. apart, tawny changing to gray 

 or black, enlarging but slightly with age; spicules yellow, about 2 mm. in 

 length, never formidable and not increasing with age; spines none; fruit 

 purple throughout, bearing light, tawny, subcircular areoles, 1 or 2 mm. 

 in diameter, having a small central tuft of yellow spicules; seeds flattened, 

 regular, about 4 mm. in diameter, prominently notched at hilum, with 

 marginal callus about J mm. in width. 



The species is rather closely related to Opuntia texana, 

 which in turn belongs to the 0. Lindheimeri group. It differs 

 from that species mainly in the absence of spines, difference 

 in areoles, and a decidedly larger seed than either of the fore- 

 going species. 



The type is No. 9422 D. G., collected near Devils River, 

 Texas, July 22, 1908. The description was written beside 

 the type plants in the field.— Plates 11; 2, f. 1; 13, f. 4. 



