74 



THE CACTACEAE. 



7. Pachycereus marginatus (De Candolle) Britton and Rose, Contr. U. S. Nat. Herb. 12: 421. 1909. 



Cereus marginatus De Candolle, Mem. Mus. Hist. Nat. Paris 17: 116. 1828. 

 Cereus gemmatus Zuccarini in Pfeiffer, Enum. Cact. 96. 1837. 



-Flower of P. chrysomalhis. X0.7. 



Fig. 109. — Longitudinal section of flower 

 of P. chrysomallus. X0.7. 



Stems 3 to 7 meters high, erect, usually simple; ribs 5 or 6 (7 in the original specimen), some- 

 what acute when young, obtuse in age; areoles close together, usually confluent, their wool forming 

 a dense white cushion along the ridge of each rib; spines at first 5 to 8 (1 central), in old areoles more 

 numerous, 1 cm. long or less, but in flowering areoles often numerous, bristly and 2 cm. long; flowers 

 and fruit usually closely set, one above the other, apparently only one at an areole, but recorded as 

 often geminate, and appearing anywhere along the ribs from the top downward; flower funnelform, 

 3 to 4 cm. long including the ovary; tube and ovary more or less scurfy and with ovate scales sub- 

 tending bunches of wool and small spines; fruit globular, about 4 cm. in diameter, not very fleshy, 

 yellowish red within, covered with spines and wool which finally drop off; seeds numerous, black, 

 and somewhat shining, rather large, 4 mm. long, the hilum depressed. 



Type locality: Mexico. 



Distribution: Hidalgo, Oueretaro, and Guanajuato, and widely planted 

 and naturalized throughout Mexico. 



This species is commonly cultivated throughout central and southern 

 Mexico as a hedge plant and when properly cared for forms an impene- 

 trable barrier; it is there called organo. 



Cereus cupulatus, Cereus incrustatus, and Cereus mirbelii are all re- 

 ferred by Pfeiffer (Enum. Cact. 97. 1837) to this species. Cereus incrus- 

 tans Steudel (Nom. ed. 2. 1: 334. 1840) was only a garden name but was 

 referred to this species by Steudel. 



Illustrations: Contr. U. S. Nat. Herb. 5: pi. 59, 60; Bull. Soc. Acclim. 

 France 52 : f . 8; Monatsschr. Kakteenk. 19:62; Reiehe, Veg. Aired. Cap. 

 Mex. f. 21, 22; Schumann, Gesamtb. Kakteen f . 17; U. S. Dept. Agr. Bur. 

 PI. Ind. Bull. 262: pi. 6; Journ, Intern. Gard. Club 3: 18, all as Cereus marginatus; Mo- 

 natsschr. Kakteenk. 23:149, as Cereus marginatus gibbosus; Cact. Journ. 1:59; 2:169, 

 as Cereus gemmatus; Schelle, Handb. Kakteenk. f. 22, as C. marginatus gemmatus. 





Fig. 110. — Flower 

 of P. marginatus. 

 Natural size. 



