LEPTOCEREUS. 77 



10. LEPTOCEREUS (Berger) Britton and Rose, Contr. U. s. Nat. Herb. 12: 43.?. [909. 



Arborescent, bush-like, vine-like, or diffusely branching cacti; joints with 3 to 8 prominent, thin, 

 high, crenate ribs, without aerial roots; spines slender, aeieular; flowers diurnal, small; pvary spins'; 

 flower-tube short, campanulate, spiny; stamens very aumerous, borne at the base of the throat, 

 scarcely exserted; stigma-lobes a little exceeding the stamens; fruit globose to oblong, more or less 

 spiny, fleshy; seeds numerous, black. 



Type species: Cereus assurgens Grisebach. 



This genus is composed of eight species, six of them Cuban, one Santo Domingan, and 

 one Porto Rican. Some are weak and clambering; others develop woody trunks. The 

 branches are strongly ribbed and armed with clusters of long aeieular spines. The earliest 

 species were referred to Cereus. Leptocereus assurgens and L. quadricostatus, the only 

 species known to Schumann, were placed by him in different sections of the genus Cereus, 

 the former in his series Tortuosi and the latter in his series Oligogoni. A. Berger in his 

 treatment of Cereus proposed the subgenus Leptocereus, which we afterward raised to 

 generic rank. Cereus gonzalezii and C. tonduzii, also referred here by Berger, we have 

 referred to other genera. 



The generic name is from the Greek, signifying thin-cereus, referring to the thin ribs. 



Key to Species. 



Ultimate joints slender, 1 to 2 cm. thick. 



Vine-like, elongated; ultimate joints 1 cm. thick, 4 to 7-ribbed 1. L. weingartianus 



Ultimate joints 2 cm. thick, 6 to 8 ribbed. 



Tree-like, 5 meters high, the trunk 3 cm. in diameter at the base; flowers 3.5 cm. long, 



sparingly short-spiny 2. L. leonii 



Prostrate, creeping; flowers 1.5 cm. long, densely long-spiny 3. L. prostratus 



Ultimate joints stout, 2 to 6 cm. thick. 

 Fruit densely long-spiny. 



Bush-like, 1 to 3 meters high; ultimate joints 2 to 3 cm. thick; fruit 3 to 6 cm. long. 



Joints 4-ribbed; spines brown 4. L. assurgens 



Joints 5 to 7-ribbed; spines yellow 5- L. maxonii 



Tree-like, 5 to 6 meters high; ultimate joints 5 to 6 cm. thick; fruit 8 to 10 cm. long. . .6. L. arborcus 

 P"ruit sparingly short-spiny; tree-like species. 



Joints 5 to 7-ribbed, the ribs very broad; fruit 7 to 8 cm. long 7. L. sykestris 



Joints 3 to 4-ribbed, the ribs low; fruit 3 to 5 cm. long 8. L. quadricostatus 



1. Leptocereus weingartianus (Hartmann). 



Cereus ■weingartianus Hartmann in Dams, Monatsschr. Kakteenk. 14: 155. 1904. 

 Roots in clusters, tuberous, thick; stems becoming terete and woody below, the branches 

 creeping or climbing among shrubs and trees, sometimes to the height of 8 to 10 meters; stems 

 4 to 7-ribbed, at first slender and weak, 1.5 to 2 cm. in diameter; areoles 1 to 1.5 cm. apart, circular, 



Fig. 112. — Part of branch of L. weingartianus. X0.7. 



small, at first filled with short, whitish wool (afterwards disappearing) and aeieular spines at 

 first brownish or yellowish brown but in age becoming gray; radial spines 10 to 12, spreading; central 

 spines a little stouter than the radials, a little spreading, often as many as 6, bulbose at base, 1 to 

 1.5 cm. long; flowers small, about 4 cm. long; fruit about 2 cm. long, covered with clusters of small, 

 deciduous spines. 



Type locality: Haiti. 

 Distribution: Hispaniola. 



This species has heretofore been known only from the type material from "Haiti." 

 In 1913 Dr. Rose collected an abundance of both living and herbarium material near 



