CACTACE^ OF MEXICO SAPFOED. 551 



tubercled Echinocacti to which E. hexaedrophorus (pi. 13, fig. 3) and 

 E. scheerii (pi. 3, fig. 3) belong.'' 



Tnbe Eehinocactece. 



1. Cereus and its allies. — The plants which have been grouped to- 

 gether under this name vary considerably in the characters of their 

 flowers and fruit. They naturally form several distinct divisions 

 which have been regarded by various authors as subgenera, or, in a 

 few cases, as genera. Among the most recent authorities to treat of 

 the group are Britton and Rose, who have established a number of 

 new genera and have raised the giant sahuaro, or suguaro, of our 

 southwestern deserts into a monotypic genus, named Carnegiea,^ after 

 Mr. Andrew Carnegie, to whose generosity the Desert Laboratory of 

 the Carnegie Institution owes its existence.'' The most important 

 studies of the genus thus far have been those of Mr. Alwin Berger, 

 published in the Sixteenth Report of the Missouri Botanical Garden, 

 1905, and Britton and Rose in volume 12 of Contributions from the 

 National Herbarium, pages 413 to 437, 1909. From the classification 

 of Berger and from Britton and Rose I take the following list of 

 genera : 



Cereus, as understood by Britton and Rose, includes Cereus hexa- 

 goiiKs (usually called C. peruvianvs) and C. jamacaru, night-flower- 

 ing cacti with columnar upright, branching, ribbed, fluted, or angled 

 stems and branches, and beautiful white flowers with numerous sta- 

 mens and many-rayed stigma. Though of South American origin 

 these species are now widely spread in the West Indies, the first also 

 in Central America and tropical Mexico. 



Rathbunia, named by Britton and Rose in honor of Dr. Richard 

 Rathbun, Assistant Secretary of the Smithsonian Institution in 

 charge of the U. S. National Museum, includes several, species in- 

 digenous to the coast of Western Mexico, among them Rathhunia 

 alamosensis {Cereus aJamosensis Coulter), a plant with sharp irregu- 

 lar ribs, brown velvety areoles, stout spines, and bright salmon-colored 

 trumpet-shaped day-blooming flowers, first collected by Doctor Pal- 

 mer, near Alamos, southern Sonora. 



Nyctocereus, the type of which, Nyctocereus serpentinus, called 

 junco espinoso in the State of Jalisco, is often seen in collections. 

 This species has straggling cylindrical fluted stems and branches with 

 numerous areoles bearing a tuft of white wool and weak radiating 



" Engelmanu, George. Cactacese of the Mexican Boundary, p. 46. 1859. 



* Britton, N. L., and Rose, J. N. A New Genus of Cactacese. Journ. New 

 Yorlv Bot. Garden, vol. 9, p. 185. 1908. 



''•See Coville, Fi-edericli V., and MacDougal, D. T., " Desert Botanical Labora- 

 tory of tlie Carnegie Institution," Publication No. 6 of ttie Carnegie Institution 

 of Washington. 



88292— SM 1908 36 



