ILLUSTRATED STUDIES IN THE GENUS OPUNTIA — II. 89 



sheathed with white glistening sheaths which are yellow distally, 

 but spines at first red turning to flesh-colored, becoming chalky white 

 later; flowers not seen; fruit distinctly and characteristically proliferous but 

 usually producing some seed, tubercular, like stem even in age with the 

 same sharp limiting dark lines surrounding the tubercles, its areoles 

 obovate, about 2 mm. in greatest diameter, bearing a prominent bunch 

 of yellow spicules about 1 mm. in length and the upper one usually bear- 

 ing a typically sheathed spine 6 to 7 mm. long and 2 to 4 delicate, fugacious 

 bristles 2 to 3 mm. long in lower portion of areole in addition to the regular 

 tuft of shorter spicules, green or slightly yellowish tinged when mature 

 but always greenish within, very variable in size, the proliferous forms 

 being 1.5 cm. by 3 to 4 cm., while the less proliferous and fertile forms are 

 1 cna. by 1.5 to 2 cm. 



The relationships of this species are somewhat ambiguous. 

 It has some ear marks of Opuntia neoarbuscula, which it re- 

 sembles in habit, but from which it differs decidedly in its 

 proliferous, tuberculate fruits, fewer spines, usually poor seed 

 habits, and tuberculate stems. It resembles in some respects 

 Opuntia Kleiniae, but its habit is entirely different and the 

 fruits and stems are too tubercular to be admitted into that 

 species. It grows associated with a dwarf form of Opuntia 

 Whipplei, some varieties of which it resembles in the tuber- 

 culation of its fruits, but these fruits are smaller, the plant is 

 in general much less spiny, the stems are smaller and less 

 tuberculate. On the whole, it probably belongs closer to 

 Opuntia neoarbuscula than any other species. A single joint 

 or some stems might be selected which would pass fairly well 

 for Opuntia arhuscula, but the fruits will not admit of its being 

 referred to this species. 



In the above description the spicules are said to be yellow, 

 and this is true of the type specimen. However, specimens 

 were found after the description was written having reddish- 

 brown spicules. So we must consider the spicules in this spe- 

 cies, as in scores of others, to vary from yellow to reddish- 

 brown when young. Upon old joints the reddish-brown 

 spicules become a dirty yellow. 



The type is No. 9568 D. G., collected near Hillside, Arizona, 

 September 10, 1908. The description is a compilation of 

 field notes taken beside the yellow-spiculed plant supple- 

 mented by laboratory studies of both varieties. — Plates 8; 2, 

 f.4and7;13, f. 5. 



