596 MISC. PUBLICATION 42 3, U. S. DEPT. OF AGRICULTURE 



occasionally attaining a height of more than 50 feet and developing 

 as many as 50 "arms." Large individuals are believed to be from 150 

 to 200 years of age. The flowers are nocturnal, opening between 9 

 and 12 o'clock at night. They open slowly, full expansion requiring 

 about 2 or 3 hours; and persist in full flowering stage until late the 

 following afternoon when they begin to close and wither. The 

 large and beautiful white flowers are not fragrant but have an odor 

 like that of ripe melon (see frontispiece) . 



The sahuaro (pi. 19) has contributed substantially toward the sub- 

 sistence of the Pima and Papago Indians, furnishing materials for 

 food and shelter. The great capacity for storing water, combined 

 with slow rate of growth, enables the plant to fruit annually more or 

 less irrespective of drought. The fruit, or pitahaya of the early Span- 

 iards, matures in June and July. The watermelon-red pulp is eaten 

 fresh or stored, and in the form of sirup and preserves. At the annual 

 harvest an intoxicating beverage is prepared by allowing the juice to 

 ferment. The Papagos make a sort of butter from the seeds. The 

 white-wing dove, a favorite game bird of Arizona sportsmen, feeds 

 largely on the seeds of the sahuaro during the fruiting season. 



4. Cereus thurberi Engelm., Amer. Jour. Sci. ser. 2, 17: 234. 1854 



Lemaireocereus thurberi Britt. and Rose, Carnegie Inst. Wash. 

 Pub. 248. 2: 97. 1920. 



Southern Pinal, southern Maricopa, and western Pima Counties, 

 up to about 3,000 feet, May to July. Arizona, Sonora, and Baja 

 California. 



Organpipe cactus (pi. 20). The flowers open shortly after sunset 

 and close the following day. The inner perianth segments are pale 

 pink in the center, white along the margin and toward the base. 

 The large, globose, extremely spiny fruits are highly esteemed by the 

 Papago Indians. The old name, pitahaya dulce, denotes the sweet- 

 ness of the pulp. A large area in the desert south of Ajo, Pima County, 

 has been set aside as a national monument for the preservation of the 

 organpipe cactus and the sinita. 



5. Cereus schottii Engelm., Amer. Acad. Arts and Sci. Proc. 3: 288. 



1856. 



Lophocereus schottii Britt. and Rose, Con trib. U. S. Natl. Her- 

 barium 12: 427. 1909. 



Western Pima County, 1,000 to 2,000 feet, April to August. Ari- 

 zona, Sonora, and Baja California. 



Sinita. The odorless pink flowers open soon after sunset and 

 wither the following morning (pi. 21). 



Cereus alamosensis Coult. (Rathbunia alamosensis Britt. and Rose), which is 

 known in Sonora, Sinaloa, and Tepic, has been dubiously reported from western 

 Pima County. This species has weak, usually reclining stems, and scarlet 

 flowers. 



2. ECHINOCEREUS. Hedgehog cactus, strawberry cactus 



Plant small, rarely 0.5 m. high, cespitose or simple ; stems 1-jointed, 

 cylindric or ovoid, erect or strongly ascending; spines not hooked; 

 flowers funnelform or subcampanulate, arising from a rupture of the 

 epidermis immediately above mature lateral spiniferous areoles, 

 diurnal, lasting several days; hypanthium scales small, acute, entire, 



