84 MISSOURI BOTANICAL GARDEN. 



mm. long; areoles subcircular to obovate, about 3 mm. in longest diameter, 

 but increasing in size with age to even subcircular and 4 mm. in diameter, 

 2.5 to 3.5 cm. apart; wool tawny brown, giving its characteristic color to 

 the young areoles which, however, is early obliterated by the spicules 

 which are yellow, numerous, formidable, 2 to 4 mm. long, in a compact, 

 mostly connivent tuft, filling nearly the entire areole; spines none, or an 

 occasional one bleached white distally with tinted base, erect, flattened, 

 twisted, faintly annular; flowers yellow; fruit light red, lighter or mottled 

 within, smooth with very small subcircular areoles and but few incon- 

 spicuous spicules, obovate-clavate, about 2 by 4.5 cm. ; seeds subcircular, 

 rather thick, mostly a little less than 5 mm. in diameter, with narrow 

 marginal commissure. 



The species is more closely related to 0. vulgaris than any- 

 other species, but it differs in shape and surface of joints as 

 well as in habit and general aspect of the plant. 



The type is No. 322, San Antonio garden. The original 

 material was collected by Mr. Allaire near the mouth of Trin- 

 ity River, Texas, in April, 1908. This has been grown and 

 has produced flowers and fruit during the past season and was 

 in bloom when received. The description is a compilation of 

 field notes and laboratory studies from abundant living ma- 

 terial. I take pleasure in dedicating this species to Mr. C. B. 

 Allaire, who collected it and supplied the material from which 

 plants have been grown and descriptions drawn. — Plates 5; 2, 

 f. 2; 12, upper figure; 13, f. 9. 



O. Whipplei Engelm. & Bigel. and 0. echinocarpa Engelm. 

 & Bigel. 



On pages 102 to 105 of Bulletin No. 60 of the Agricultural 

 Experiment Station of New Mexico, published in 1906, Grif- 

 fiths and Hare discuss two somewhat distinct forms of 0. 

 Whipplei. An opportunity was had during the past season 

 of studying these forms further. There is no doubt but that 

 the two forms referred to in that publication are the same 

 species. The differences are due to differences of altitude, 

 rainfall or soil conditions, or all combined. This species reg- 

 ularly dwarfs, becomes more proliferous-fruited and more 

 sterile in its seed habits as one goes down the mountain sides 

 from the altitude of Fort Whipple, Arizona, where it may be 

 5 feet high or more. 



