i6o 



THE CACTACEAE. 



Joints elongated-lanceolate or oblong, several times longer than wide 175. 0. linguiformis 



Joints obovate to suborbicular. 

 Spines long. 



Areoles mostly 1.5 to 2 cm. apart. 



Spines subulate, up to 7.5 cm. long 176. O. tapona 



Spines acicular, 4 cm. long or less. 



Spines nearly clear yellow, short 177. 



Spines brown at base, long and slender 178. 



Areoles mostly 2.5 to 4 cm. apart. 

 Bushy species. 



Spines yellow or yellowish brown 179. 



Spines pale yellow or whitish 180. 



Depressed or procumbent plant 181. 



Spines only 1.5 cm. long or less, or becoming longer on old joints. 



Plant I meter high or less; joints thin 182. O. Canada 



Plant 3 to 5 meters high ; joints very thick. 



Spines reflexed; flowers yellow 183, 



Spines spreading, deciduous; flowers orange-red 1830, 



171. Opuntia chlorotica Engelmann and Bigelow, Proc. Amer. Acad. 3: 291. 1856. 



O. litloralis 

 0. aciculata 



0. lindheimeri 

 O. cantabrigiensis 

 O. procumbens 



0. pyriformis 

 0. bonplandii 



Opuntia tidballii Bigelow, Pac. R. Rep. 4: 11. 1856. 

 Opuntia curvospina Griffiths, Bull. Torr. Club 43: 88. 



1916. 



Krect bushy, sometimes 2 meters high or more, with a definite trunk; main branches nearly 

 erect; joints ovate to orbicular, sometimes broader than long, 15 to 20 cm. long, more or less glau- 

 cous, bluish green; leaves subulate, small, reddish at tip; areoles closely set, prominent; spines 

 yellow, several, most of them usually appressed and reflexed, setaceous, 3 to 4 cm. long; glochids 

 yellow, numerous, elongated, persistent; flowers yellow, 6 to 7.5 cm. broad; filaments white; fruit 

 purple without, green within, 4 cm. long; seeds small. 



Fig. 199. — Opuntia chlorotica. 



Fig. 200. — Opuntia chlorotica. X0.4. 



Type locality: On both sides of the Colorado from San Francisco Mountains to head- 

 waters of Bill Williams River. 



Distribution: Sonora and New Mexico to Nevada, California, and Lower California. 



This species is of wide distribution, but is chiefly confined to mountain canyons, being 

 rarely found on the open mesas. 



Illustrations: Bull. Torr. Club 43: pl. y, Pac. R. Rep. 4: pl. 6, f. i to 3; Bull. Torr. 

 Club 43: pl. 2, this last as Opuntia curvospina. 



