90 MISSOURI BOTANICAL GARDEN. 



Opantia cauada sp. nov. 



Plant erect and ascending, spreading, rather compactly branched, 

 about 9 dm. high and 12 or more dm, in diameter, growing commonly in 

 thickets, but also frequently as isolated individuals; joints obovate to ovate, 

 mostly broadly rounded above, about 16 by 22 cm. in second year joints 

 but quite variable, yellowish, smooth and shining green when young, 

 turning darker and more or less glaucous the second year; leaves circular in 

 section, subulate, mucronate pointed, about 1 cm. in length; areoles sub- 

 circular, brown when young, turning through dirty gray to black, but 

 often retaining a brown center surrounded by a grayish or black zone owing 

 to continued development of new wool from the central areolar area, 

 broadly obovate, 5 mm. in greatest diameter but increasing in size with 

 age and becoming subcircular, very prominent; wool light tawny when 

 removed, but dark brown in situ, prominent; spicules very variable, often 

 few or none until 1 or 2 years old, when they become conspicuous, unequal, 

 often 12 mm. in length, upon last year's joints when present they are 2 to 

 3 mm. long, always unequal, scattered, light reddish-brown when young, 

 turning yellow or dirty yellow in age; spines exceedingly variable in every 

 characteristic, bleached white with usually tinted bases mostly completely 

 white after a year or two, commonly yellow when young, but soon present- 

 ing the bleached, white appearance, flattened, sometimes twisted slightly, 

 never annular, but minutely longitudinally striate under a lens, 1 to 4 or 

 5, mostly 2 or 3, 12 to 15 mm. in length on second year joints, but fre- 

 quently increasing in both length and numbers upon old trunks; flowers 

 yellow with tinge of red or deep orange on inside at bases of petals and 

 often outside as well, stigma bright green and style varying from white to 

 reddish-tinged; fruit light red, often mottled yellow and red, usually not 

 uniformly colored, rind greenish-yellow and pulp lighter in color, its areoles 

 usually gray on border and tawny brown within, the spicules being very 

 light brown; seeds flattened but mostly quite thick, angular, between 3 

 and 3.5 mm. in diameter, with a prominent, rounded, roughened mar- 

 ginal callus, and prominently notched hilum. 



The species is most closely related to the spiny form of 

 Opuntia laevis, from which it differs in greater spininess, dif- 

 ference in color of plant body, larger, more robust plant, and 

 in the nature of its fruit. The seeds of the two species are 

 also different. It commonly grows upon the sides of arroyos 

 and canyons from the lower foothills to the beginning of the 

 oak timber and is rather common throughout the locality 

 mixed with the spiny forms of Opuntia laevis, from which it 

 is sometimes difficult to distinguish it, except in flower and fruit. 



The type is No. 9593 D, G., collected in the foothills of the 

 Santa Rita Mountains, Arizona, September 17, 1908, The 



