OPUNTIA. 149 



151. Opuntia discata Griffiths, Rep. Mo. Bot. Card. 19: 266. 1908. 



Opuntia gilvesceiis Griffiths, Rep. Mo. Bot. Card. 20: 87. 1909. 

 Opuntia riparia Griffiths, Proc. Biol. Soc. Washington 27: 26. 1914. 



Plants bushy, spreading, sometimes 15 dm. high; joints thick, orbicular to broadly obovate, 

 2.5 dm. in diameter or less, pale bluish green, somewhat glaucous; areoles rather few, distant, in 

 age becoming very large, hemispheric, filled with short brown wool; spines usually 2 to 4, sometimes 

 7 or more in old areoles, 2 cm. long or more, grayish with dark bases, somewhat flattened; flowers 

 large, 9 to 10 cm. broad, light yellow, darker near the center; style white; stigma-lobes green; fruit 

 magenta, pyriform, 6 to 7 cm. long. 



Type locality: Foothills of Santa Rita Mountains, Arizona. 



Distribution: Foothills and high mesas of southern Arizona and northern Sonora. 



Illustrations: Rep. Mo. Bot. Gard. 20: pi. 2, f. 5; pi. 7; pi. 13, f. 6, all as Opuntia gil- 

 vcscens; Amer. Garden n: 469, this last as Opuntia angustata. Ariz. Agr. Exp. Sta. Bull. 

 67: pi. i, f. 2; Bull U. S. Dept. Agr. 31: pi. 3, f. 2; Rep. Mo. Bot. Gard. 19: pi. 27, in part. 



Plate xxiv, figure 2, is from a photograph taken by Dr. MacDougal in the Tortolita 

 Mountains, Arizona, in 1916; Opuntia discata is the plant shown in left foreground. 



152. Opuntia rastrera Weber, Diet. Hort. Bois 896. 1898. 



? Opuntia lucens Griffiths, Rep. Mo. Bot. Gard. 19:269. 1908. 



Creeping plant; joints circular to obovate, the largest 2 dm. in diameter; spines white, several 

 from an areole, the longest 4 cm. long; glochids yellow; flowers yellow; fruit purple, acid, obovoicl. 



Type locality: San Luis Potosi, Mexico. 



Distribution: The type locality and vicinity. 



This species was very briefly described in 1898 by Dr. Weber, who states that it is 

 quite distinct from 0. tuna, the Jamaican species. Schumann, who treats it in a note under 

 0. tuna, states that it is a well-differentiated species from Mexico. 



From descriptions we are referring here 0. Inccns Griffiths, also described from San 

 I/uis Potosi specimens. Dr. Griffiths states that his 0. lucens is related to 0. engelmannii, 

 but has a different habit; he says it is called cuija by the Mexicans, but that it is very 

 different from Opuntia cuija. 



Series 12. ELATIORES. 



Tall species, with flat, broad, persistent joints, the areoles bearing acicular, setaceous, or subulate 

 brown spines, or some species spineless. We know about twelve species, most of them South 

 American, with one in Florida (see Appendix p. 222), possibly one (0. fuliginosa) in Mexico. 



KEY TO SPECIES. 



Joints very spiny. 

 Spines not banded. 



Areoles surrounded by a purple blotch 153. 0. brunnescens 



Areoles not surrounded by a purple blotch. 



Spines setaceous; petals yellow 154. 0. galapageia 



Spines, when present, acicular or subulate; petals mostly red or orange. 



Joints strongly undulate; spines short, stout 155. O. delaetiana 



Joints not undulate or scarcely undulate. 



Joints bluish green, glaucous 156. O. bergeriana 



Joints bright green, not glaucous or slightly glaucous 

 Spines, at least on young joints, acicular, slender. 



Spines, when present, dark brown or blackish; joints dull 157. 0. elatior 



Spines light brown to straw-colored. 



Spines up to 5 cm. long; joints shining 158. 0. hanburyana 



Spines 3 cm. long or less; joints dull. 



Flowers 12 to 15 mm. wide; spines i to 4 at an areole or 



wanting 159. O. quitensis 



Flowers 5 to 6 cm. wide; spines up to 10 at an areole 1591. O. soederslromiana 



Spines subulate, stout; joints shining 160. 0. scltumannii 



Spines acicular; petals yellow; joints shining (in this series?]. .. 161. O. fuliginosa 



Spines distinctly banded; joints dark green, obscurely glaucous . . . i6ia. O. zebrina 



Joints usually spineless. 



Bushy, i to 2 meters high; flowers rose 162. 0. boldinghii 



Erect, 3 to 4 meters high; flowers orange-red 163. U. distans 



