168 MISSOURI BOTANICAL GARDEN. 





ft is, therefore, in all probability, able to thrive upon land 

 containing considerable soluble salts. It is often found 

 growing scatteringly upon land entirely devoid of brush 

 and which periodically overflows. In these areas, however, 

 it frequently gets killed out on account of the overflows 

 which occur at irregular intervals, and again becomes estab- 

 lished thinly before another period of overflow occurs. 



The description was drawn in the field when the type 

 specimen was collected, notes on the flowers being subse- 

 quently secured. The type specimen is No. 9913 D. G., col- 

 lected near Brownsville, Texas, March 13, 1910. It is 

 named in honor of Mr. William Gome, whose assistance it is 

 a pleasure to acknowledge. — Plates 21 and 22, lower figure. 



Opuntia pachona sp. nov. 



Plant tall, arborescent, widely branching but not as divergent as 

 O. streptacantha, with distinct cylindrical trunk 1 to 1.5 meters long, 

 the whole plant normally 3 to 5 meters high; joints about 20 by 32 

 cm., obovate, deep dark green, with often a white bloom, similar to 

 O. streptacantha in color but on the whole a little lighter; areoles 2£ 

 to 3 cm. apart, ovate to sub-circular; spicules bright dark reddish 

 brown, often formidable, in compact tufts in upper part of areoles, 



length wi 



triangula 



mostly slightly but never tightly recurved, 2 to 5 or 6 in number, 

 mostly 2 to 4 on last year's joints, increasing on old trunks to 6 or 8 

 and becoming larger and stouter than on young joints, diverging in all 

 directions upon old trunks although upon young joints they are slightly 

 recurved or sloping downward; fruits about 40 to 45 by 50 to 55 mm. 

 bright, glossy, purplish-red when mature, beset with rather large cir- 

 cular areoles containing formidable reddish brown spicules surrounded 

 by the blackened ends of the dark tawny wool. 



Opuntia pachona belongs to an important group of prickly 

 pears of the highland of Mexico in which the expressed 

 juice contains a large amount of solids in suspension. It 

 is, therefore, one of the forms used in the manufacture of 

 queso. Although similar in color to 0. streptacantha, it 

 can hardly be considered as closely related to this species, 

 but should be looked upon as representing the Opalillo- 

 Lionero group none of which, so far as I am aware, have 

 satisfactory descriptions. 



The description is a compilation from two sets of char- 



