STANDLEY TREES AND SHRUBS OF MEXICO. 909 



Plant pale green when young, similar to H. speciosus in habit and spines; 

 ribs 3 to 5 ; flower 11 cm. long, 8 to 12.5 cm. in diameter ; flower tube 3.5 cm. 

 long, 1 cm. in diameter, green, with green scales and whitish bristles ; outer pe- 

 rianth segments yellowish green, grading into oblanceolate white inner seg- 

 ments, 7 cm. long, 2 cm. wide ; ovary cylindric, 6 mm. long. 



17. CARNEGIEA Britt. & Rose, Journ. N. Y. Bot. Gard. 9: 187. 1908. 



A single species is known. 



1. Carnegiea gigantea (Engelm.) Britt. & Rose, Journ. N. Y. Bot. Gard. 9: 

 188. 1908. 



Cereus giganteus Engelm. in Emory, Mil. Reconn. 159. 1848. 



Pilocereus engelmannii Lem. Illustr. Hort. Lem. 9: Misc. 97. 1862. 



Sonora. Southern Arizona and California ; type from the Gila River, Ari- 

 zona. 



Stem simple and upright, up to 12 meters high, or with one or two lateral 

 branches, sometimes with 8 to 12 branches, the branches 30 to 65 cm. in diam- 

 eter ; ribs 12 to 24, obtuse, 1 to 3 cm. high ; areoles about 2.5 cm. apart or 

 nearly contiguous on the upper part of the plant, densely brown-felted ; spines 

 of two kinds, those at the top of flowering plants acicular, yellowish brown, 

 porrect, those of sterile plants and on the lower parts of flowering plants more 

 or less subulate, the central one stouter than the radials, often 7 cm. long; 

 flowers 10 to 12 cm. long, sometimes nearly as broad as long when fully ex- 

 panded; tube about 1.5 cm. long, green, its scales broad and short, white- 

 felted in their axils; throat about 3 cm. long, covei'ed with numerous white 

 stamens ; style stout, 5 to 6 cm. long, white or cream-colored ; ovary some- 

 what tuberculate, bearing scales with woolly axils ; ovules numerous ; berry 

 red or purple, obtuse, 6 to 9 cm. long, edible, its few distant scales ovate, 

 2 to 4 mm. long, with or without 1 to 3 short acicular spines in their axils. 

 " Pitahaya," " saguaro," " sahuaro " (sometimes variously written suwarrow, 

 suwarro, suaharo, suguaro). 



This is the state flower of Arizona. It is a very abundant and conspicuous 

 plant in the southern part of that State and in northern Sonora.* The dried 

 woody ribs of the stems were used by the Indians for lances and for the frame- 

 work of huts. The fruit was an important article of food among all the 

 Indians of the region. It was eaten raw or cooked and was sometimes dried 

 and preserved for winter use. From it^ there was prepared a thick syrup 

 which was employed for sweetening other food, and also an intoxicating 

 beverage. The seeds contain much oil, and by the Papagos they were ground 

 into a paste which was spread like butter upon tortillas. They were also 

 eaten raw or ground and made into pinole. The seeds were sometimes collected 

 and eaten after having passed through the body, a practice that was followed 

 also by some of the Californian Indians in the case of Opuntia seeds. 



18. RATHBUNIA Britt. & Rose, Contr. U. S. Nat. Herb. 12: 169. 1909. 



Rather slender cacti, simple or bushy, the stems and branches weak, erect or 

 bent; ribs 4 to 8, prominent; spines subulate, those of the flowering areoles 

 not differing from the others ; flowers diurnal, scarlet, solitary, usually at the 

 upper areoles, narrowly tubular, the tube bearing distant long scales and 



* See D. T. MacDougal, The suwarro, or tree cactus. Journ. N. Y. Bot. Gard. 

 6: 129-133. /. 31, 32. 1905. 



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