STANDLEY TEEES AND SHKUBS OF MEXICO. 891 



2. Cephalocereus hoppenstedtii (Weber) Schum. in Engl. & Prantl, 



Pflanzenfam. 3"'': 181. 1894. 



Pilocereus hoppenstedtii Weber, Cat. Pfersdorff. 1864. 



Pilocereus hagendorpi Re^el, Gartenflora 18: 220. 1869. 



Pilocereus lateralis Weber, Diet. Hort. Bois 966. 1898. 



Cereus hoppenstedtii Berger, Rep. Mo. Bot. Gard. 16: 70. 1905. 



Southern Mexico, the type from ZapotitlSn, Puebla. 



Slender, columnar, said sometimes to reach 10 meters in height, often bent 

 or clambering, the apex tapering; ribs low, close together, 20 or more, the 

 whole plant hidden under the numerous spines ; areoles close together ; 

 radial spines 14 to 18, very short, white ; central spines 5 to 8, the longest 

 one sometimes 7.5 cm. long, usually reflexed, brownish ; pseudocephalium at 

 the top of the plant but to one side (said to be on the north side) ; flower 

 described as 7.5 cm. long, whitish, with rosy tips, bell-shaped. 



3. Cephalocereus macrocephalus Weber; Schum. Gesamtb. Kakt. 197. 1897. 

 Cereus macrocephalus Berger, Rep. Mo. Bot. Gard. 16: 62. 1905. 



Puebla, the type from Tehuac^n. 



Plant of great size, 10 to 16 meters high, with a very solid woody trunk 30 

 to 60 cm. in diameter, simple or with a few ascending branches ; pseudocepha- 

 lium not so conspicuous as in Cephalocereus senilis; ribs numerous (about 24), 

 low, obtuse, pale green ; radial spines about 12, spreading ; central spines several, 

 sometimes 6 cm. long; flowering areoles spineless but bearing white stiff hairs 

 or weak bristles; pei'ianth about 5 cm. long, the tube bearing a few distant 

 scales, the limb short, the outer segments rounded. 



4. Cephalocereus polylophus (DC.) Britt & Rose, Contr, U, S. Nat. HerL 



12: 419. 1909. 



Cereus polylophus DC. Mem. Mus. Hist. Nat. 17: 115. 1828. 



Eastern Mexico. 



Erect, with simple stems 10 to 13 meters high, green ; ribs 15 to 18 ; areoles 

 small, 1 cm. apart or less, bearing white felt but no wool ; spines 7 or 8, yellow, 

 straight, spreading ; central spine single, longer than the others ; flowers 4 to 

 5 cm. long, about 3 cm. broad at top, narrowly funnelform ; free part of tube 

 G to 8 mm. long with ridges down the inside ; stamens included, inserted on the 

 throat ; inner perianth segments probably red, broad and short, rounded at 

 apex ; ovary somewhat tuberculate ; scales small, without felt, wool, or hairs in 

 their axils ; scales of flower tube small, acute, spreading, with the tip reflexed. 



5. Cephalocereus scoparius (Poselger) Britt. & Rose, Contr. U, S. Nat. Herb. 



12: 419. 1909. 

 Pilocereus scoparius Poselger, AUg. Gartenz. 21: 126. 1853. 

 Cereus scoparius Berger, Rep. Mo. Bot. Gard. 16: 63. 1905. 

 Type from La Soledad, Veracruz. 



Stems 6 to 7.5 meters high, 30 cm. or more in diameter; younger branches 

 with 12 to 15 ribs, these blunt ; areoles 1.5 to 2.5 cm. apart, naked ; radial spines 



5, somewhat bent downward, 5 to 8 mm. long; central spine 1, stout, bent up- 

 ward, 2.5 cm. long; flowering branches with 20 to 25 ribs; flowers small, red- 

 dish ; fruit red, small. 



6. Cephalocereus gaumeri Britt. & Rose, Cactaceae 2: 47. 1920. 

 Yucat&n. 



Plant 6 meters high, light green, slender, often only 2 to 3 cm., but some- 

 times 6 cm., in diameter ; ribs 8 or 9, 6 to 8 mm. high ; areoles 6 to 10, bear- 

 ing short felt and cobwebby hairs when young ; flowering areoles bearing tufts 



