82 MISSOURI BOTANICAL GARDEN. 



statement that it is related to 0. microdasys is possibly true, 

 it is, nevertheless, a very different plant. It is arborescent 

 with a distinct trunk, while 0. microdasys is a low, nearly pros- 

 trate species with never a true trunk * Besides, the joints 

 and flowers are different, as indicated in the original descrip- 

 tion. The fruits, which I have never seen until the past sea- 

 son, are also quite different from those of 0. microdasys. They 

 are greenish-red without, green within, decidedly acid, and 

 have very thin rinds. The seeds have very thin integuments 

 compared with the majority of the species of the genus 

 Opuntia. 



Regarding its relationships, it may be said that Engelmann 

 was only partly right in his opinion. He never saw anything 

 but a few cuttings. He was unacquainted with the habit of 

 the plant. It resembles 0. microdasys in having some pubes- 

 cence and no spines. In color of plant body and spicules, 

 however, it resembles 0. basilaris more closely. Its real re- 

 semblances, however, are to the variety Santarita of 0. chloro- 

 tica, but this is placed by the monographers in an entirely dif- 

 ferent group. 



The specimen described by Griffiths and Haref is the true 

 0. rufida, but the notes appended regarding No. 8023 D. G. 

 may represent a plant sufficiently different to warrant at least 

 sub-specific rank. The fruits of that number appear from the 

 very casual and imperfect examination to be quite different 

 from those of true 0. rufida, both in the type locality and in 

 the vicinity of Torreon, Mexico. It is seldom that the fruits 

 of the species in the type locality are entirely red on the out- 

 side. Usually the greater part of the fruit is greenish, with 

 only a blush of red on one side. My collection No. 8023, 

 therefore, requires further study.— Plates 3; 12, lower figure; 

 13, f. 3, 13. 



Opuntia Dillei sp. nov. 



Plant suberect or ascending, 15 dm. or more high and 18 or 20 dm. in 

 diameter, open branching; joints subcircular to broadly obovate or ovate, 

 often broader than long, sometimes 35 cm. in diameter and 2.5 cm. thick, 



* Compare plate 3 with plate 12, lower figure. 



t Bui. 60, Agr. Expt. Sta., New Mex., p. 82. (1906.) 



