ILLUSTRATED STUDIES IN THE GENUS OPUNTIA — II. 91 



description is a compilation of four sets of field notes supple- 

 mented by laboratory studies. — Plates 6, lower figure; 2, f. 6; 

 13, f. 2 and 12. 



Opuntia megacarpa sp. nov. 



An ascending, spreading, bushy, open-branched plant 6 to 10 dm. high 

 and 12 to 15 dm. in diameter, the main branches resting on edges of joints 

 and ascending at the extremities, the secondary ones of a joint or two in 

 length growing erectly from them; joints obovate, mostly pointed above, 

 glaucous, turning yellowish-green the second year, commonly 20 by 25 cm. 

 and often widest at middle and tapering each way, often slightly purplish 

 about the areole; areoles subcircular to obovate, 4 to 6 mm. in diameter, 

 tawny brown turning gray in age and its tissues proliferating into a convex 

 gray surface when not covered with spicules; spicules reddish brown in 

 a rather compact, quite equal, crescentic bunch in upper portion of areole, 

 about 3 mm. long but increasing with age in both numbers and length, 

 becoming unequal and even 12 or 13 mm. in length, sometimes filling the 

 entire areole; .besides the regular spicules there are a few scattering fuga- 

 cious bristles all through the areolar area of young joints; spines very long, 

 formidable, often 7 or 8 cm. in length, one or none below to as many as 

 six above, 8 cm. in length, changing successively from white through mot- 

 tled flesh-color to reddish-brown at base, and in age dull, dirty brown 

 throughout, tips always more or less translucent, bone-like even in age, 

 flattened, twisted, sometimes striate, very faintly when at all annular, 

 and this lasting only through the growing season, at first spreading in all 

 directions but later sloping downward; flowers not seen; fruit dull, purplish 

 red, often with a bleached yellowish appearance, about 38 by 82 mm., 

 rind greenish, streaked with red, and pulp greenish; seeds very large, flat- 

 tened, irregularly angular, often 8 mm. in diameter but more commonly 

 about 7, with very prominent, more or less wavy, sharp marginal callus 

 about 1.5 mm. wide, prominently notched at hilima. 



It is difficult to express satisfactorily the relationship of 

 this species. The spines in color might pass for some forms 

 of 0. phaeacantha. So might the seeds, so far as everything 

 but size is concerned. The general habit of the plant is that 

 of Opuntia procumhens, but, as indicated in the description, 

 it is difficult to admit it even into the same group with either 

 one of these species. Its main characteristics are its spini- 

 ness, large, long fruits, and exceedingly large flat seeds. 



The type specimen is No. 9501 D. G., collected near Ban- 

 ning, California, August 25, 1908. The description given 

 above is a revision of one made in the field when the plant 

 was collected.— Plates 2, f, 3; 13, f. 10. 



