908 CONTKIBUTIONS FEOM THE NATIONAI. HEKBAKIUM. 



times white; tube short but definite; inner perianth segments elongate; 

 stamens numerous, declined; ovary spiny. 



One other species is known, a native of Guatemala. 

 Flowers red. 

 Inner perianth segments acuminate. 



Style not longer than the stamens 1. H. elegantissim.us. 



Style definitely longer than the stamens 2. H. schrankii. 



Inner perianth segments apiculate, rounded or abruptly tipped. 



3. H. speciosus. 

 Flowers white 4. H. amecamensis. 



1. Heliocereus elegantissimus Britt. & Rose, Cactaceae 2: 127. 1920. 



Cereus coccineus Salm-Dyck; Pfeiff. Enum. Cact. 122. 1837. Not C. coccineus 

 DC. 1828. 



Native of Mexico. 



Stems at first erect, low, 10 to 20 cm. high ; branches often decumbent, 

 light green. 3 to 5 cm. broad, mostly 3 or 4-angled; ribs strongly undulate; 

 areoles large, 1.5 to 2 cm. apart, yellow-felted ; spines acicular, 1 cm. long or 

 less, the radial ones bristly and white, the inner stifE and recurved; flowers 

 scarlet, 10 to 15 cm. broad ; perianth segments lanceolate, acuminate, 7 cm. 

 long or less ; ovary 3 to 4 cm. long, oblong, with a few scattered spreading 

 scales. 



2. Heliocereus schrankii (Zucc.) Britt. & Rose, Contr. U. S. Nat. Herb. 12: 



434. 1909. 



Cereus schrankii Zucc. ; Seitz, Allg. Gartenz. 2: 244. 1834. 



Type from Zimapiln, Hidalgo. 



Stems ascending, branching; joints 1 to 2 cm. broad, 3 or 4-angled, some- 

 what winged, when young reddish, in age green ; areoles 1.5 to 2 cm. apart, 

 somewhat elevated ; spines 6 to 8, acicular, white when young, yellowish brown 

 in age; flowers dark red, 14 cm. broad; ovary oblong, 4 cm. long, spiny. 



3. Heliocereus speciosus (Cav.) Britt. & Rose, Contr. U. S. Nat. Herb. 12: 



434. 1909. 



Cactus speciosus Cav. Anal. Cienc. Nat. Madrid 6: 339. 1803. 



Cactus si}eciosisshnus Desf. Mem. Mus. Hist. Nat. 3: 193. 1817. 



Cereus bifrons Haw. Suppl. PI. Succ. 76. 1819. 



Cereus speciosissimus DC. Prodr. 3: 468. 1828. 



Cereus speciosus Schum. in Engl. & Prantl, Pflanzenfam. 3^^: 179. 1894. 

 Not C. speciosus Sweet, 1826. 



Region of the City of Mexico and elsewhere in central Mexico. Reported 

 from Central America. 



Stems clambering or hanging, strongly 3 to 5-ribbed ; old parts bright green, 

 young parts reddish ; ribs strongly undulate ; areoles often 3 cm. apart, usually 

 large, with felt and acicular spines; spines numerous, yellow or brownish in 

 age, 1 to 1.5 cm. long; flowers scarlet, 15 to 17 cm. long, lasting for several 

 days; perianth segments oblong, 10 to 12 cm. long, with rounded, often apicu- 

 late tips; ovary bearing scattered minute scales; fruit ovoid, 4 to 5 cm. long. 

 "Santa Marta," " xoalacatl " (Ramirez). 



4. Heliocereus amecamensis (Heese) Britt. & Rose, Contr. U. S. Nat. Herb. 



12: 129. 1909. 

 Cereus amecamensis Heese; Rother, Prakt. Ratgeb. 11: 442. 1896. 

 Cereus amecaensis Heese, Gartenwelt 1: 317. 1897. 

 Central Mexico ; tyi^e from Amecameca, State of Mexico. 



