904 CONTKIBUTIONS FEOM THE NATIONAL HERBARIUM. 



reflexed ; central spines 1 to 3, subulate, 4 to 8 mm. long ; flower 15 cm. long, 

 the segments about 3 cm. long, the tube slender, with prominent areoles on 

 knobby projections ; fruit 6 cm. long, bearing prominent clusters of black spines. 



13. MACHAEROCEREUS Britt. & Rose, Cactaceae 2: 114. 1920. 



Plants prostrate or low and bushy, often with long, horizontal or prostrate, 

 stout branches, very spiny throughout ; ribs low ; areoles large, felted, spiny ; 

 spines numerous, the centrals flattened and dagger-like ; flowers diurnal, 1 

 at an areole, long, slender, funnelform, the perianth persisting on the fruit ; 

 stamens numerous, borne on the narrow elongate throat ; ovary and lovv^er part 

 of flower tube bearing many small scales, these subtending felted areoles which 

 afterward bear clusters of spines; fruit globular, edible when young, covered 

 with clusters of spines, but when fully mature becoming naked ; seeds dull 

 black, somewhat punctate, acute on the back. 



Only two species are known. 



Plants prostrate, the tips ascending; flowers yellow 1. M. eruca. 



Plants erect, 1 meter high or less, bushy ; flowers purple 2. M. gummosus. 



1. Machaerocereus eruca (T. S. Brandeg.) Britt. & Rose, Cactaceae 2: 115. 



1920. 



Cereus eruca T. S. Brandeg. Proc. Calif. Acad. II. 2: 163. 1889. 



Baja California ; type from Magdalena Island. 



Prostrate, except the erect or ascending tips ; branches 1 to 3 meters long, 

 4 to 8 cm. in diameter, usually simple, rooting on the under surface, dying at 

 the older end and growing forward at the other ; sometimes several plants 

 starting as branches from a common parent as a center and first radiating 

 out, then dying at the rear ; ribs about 12 ; areoles large, 2 cm. apart ; spines 

 about 20, very unequal, pale gray, the outer ones terete, the inner stout and 

 flatter, the longest about 3 cm. long; flowers 10 to 12 cm. long; tube about 

 10 cm. long, nearly 6 mm. in diameter ; limb 4 to 6 cm. broad ; ovary very 

 spiny ; fruit spiny, 4 cm. long ; seeds black. " Chilenola," " chirinole." 



2. Machaerocereus gummosus (Engelm.) Britt. & Rose, Cactaceae 2: 116. 



1920. 



Cereus gummosus Engelm.; T. S. Brandeg. Proc. Calif. Acad. II. 2: 162. 1889. 



Cereus cumengei Weber, Bull. Mus. Hist. Nat. 1: 317. 1895. 



Cereus flexuosus Engelm.; Coulter, Contr. U. S. Nat. Herb. 3: 411. 1896. 



Baja California and on the adjacent islands. 



Erect or ascending, but usually not a meter high, or with long, spreading, 

 sometimes prostrate branches, the whole plant sometimes having a spread of 

 6 to 7 meters; branches 4 to 6 cm. in diameter; ribs usually 8, rarely 9, low 

 and obtuse ; areoles rather large, about 2 cm. apart ; spines stout, the radials 

 8 to 12, somewhat unequal, about 1 cm. long; central spines 3 to 6, stout, 

 flattened, one much longer than the others and about 4 cm. long; flowers 10 

 to 14 cm. long, the tube long and slender ; inner perianth segments 2 to 2.5 cm. 

 long, purple ; fruit subglobose, 6 to 8 cm. in diameter, spiny ; skin of fruit 

 bright scarlet ; pulp purple ; seeds rugose, pitted, 2.5 mm. long. " Pitahaya," 

 " pitahaya agria." 



The fruit is agreeably acid, and is much eaten. The crushed stems are 

 sometimes thrown in water to stupefy fish. For an illustration of the plant see 

 Contr. U. S. Nat. Herb. 16: pi. 126 A. 



It is apparently of this species that Clavigero writes as follows: "After 

 the harvest of the sweet pitahaya [Lemaireocereus thurleri] foUows that 



