HELIOCEREUS. 127 



23. HELIOCEREUS (Berger) Britton and Rose, Contr. U. S. Nat. Herb. 12: 433. 1909. 

 Stems usually weak, procumbent or climbing over rocks and bushes, in cultivation often bushy 

 and erect; branches strongly angled or ribbed; ribs or angles usually 3 or 4, sometimes up to 7; 

 spines of all areolcs similar; flowers diurnal, large, funnelform, only 1 at an areole, usuallv scarlet, 

 sometimes white; tube short but definite; inner perianth-segments elongated; stamens numerous, 

 declined; ovary spiny. 



Type species: Cactus speciosus Cavanilles. 



Hclioccrcus was considered a subsection of Cereus by Berger and, as stated by him, the 

 species are closely related, the chief differences being in the flowers ; they are all confined 

 to Mexico and Central America. We recognize 5 species. 



The plants are easily propagated by cuttings, but it has been our experience that they 

 are among the most difficult cacti to grow under glass. It is said, however, if plants are 

 grown out of doors during the summer, they make strong branches and flower abundantly 

 during the winter. H. speciosus has been much used in hybridizing with various species of 

 Epiphyllum, resulting in many types, some of which are greatly admired, and for which 

 new specific, varietal, and form names have been proposed. 



The name is from the Greek, meaning sun-cereus. 



Key to Species. 



Flowers red. 



Inner perianth-segments acuminate. 



Style not longer than the stamens 1. H. elegantissimus 



Style definitely longer than the stamens 2. II. schrankii 



Inner perianth-segments apieulate, rounded or abruptly tipped. 



Perianth-segments apieulate or rounded 3. H. speciosus 



Perianth-segments abruptly tipped 4. II. cinnabarinns 



Flowers white 5. H. amecamensis 



1. Heliocereus elegantissimus nom. now 



Cereus coccineus Salm-Dyck in Pfeiffer, Enum. Cact. 122. 1837. Not C. coccineus De Candolle, 1828. 

 Cereus speciosissimus coccineus Riimpler in Forster, Handb. Cact. ed. 2. 773. 1885. 

 Cereus speciosus coccineus Graebener, Monatsschr. Kakteenk. 19: 137. 1909. 

 Heliocereus coccineus Britton and Rose, Contr. U. S. Nat. Herb. 12: 433. 1909. 



Stems at first erect, low, 1 to 2 dm. 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, short, 1 cm. long or less, the radial ones bristly and white, the inner ones stiff 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; style red, slender, not longer 

 than the stamens; stigma-lobes white. 



Type locality: Mexico. 



Distribution: Mexico. 



Illustrations: Bliihende Kakteen 2: pi. 118; Monatsschr. Kakteenk. 5: 135; Pfeiffer 

 and Otto, Abbild. Beschr. Cact. 1: pi. 15, all three as Cereus coccineus. 



Plate xvii, figure 1, shows a flowering branch of a plant in the collection of the New 

 York Botanical Garden. 



2. Heliocereus schrankii (Zuccarini) Britton and Rose, Contr. U. S. Nat. Herb. 12: 434. 1909. 



Cereus schrankii Zuccarini in Seitz, Allg. Gartenz. 2: 244. 1834. 



Stems ascending, branching; joints 1 to 2 cm. broad, 3 or 4-angled, somewhat 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, large, 14 cm. broad; stamens numerous; 

 style stout, red, longer than the stamens; stigma-lobes white; ovary oblong, 4 cm. long, spiny. 



Type locality: Zimipan, Mexico. 

 Distribution: Known only from the type locality. 



We know this plant only from descriptions and the cited illustration. It must be 

 closely related to the preceding species and may not be specifically distinct from it. 

 Illustration: Pfeiffer and Otto, Abbild. Beschr. Cact. 1: pi. 27, as Cereus schrankii. 



