io8 



THE CACTACEAE. 



but a careful examination of the early literature indicates that the plant was first described 

 by Sir William Hooker in 1848 who says, "I willingly adopt a name by which the plant is 

 known on the continent." In 1850 it is described by Fischer as his own genus. 



This genus is closely related to Echinocachis and its segregates, having very similar 

 flowers and fruits, but in its elongated angled tubercles it looks very unlike any of them. 

 Engelmann suggested, although he never saw the fruit, that it might be a subgenus of 

 Mammillaria. 



1. Leuchtenbergia principis Hooker in Curtis's Bot. Mag. 74: pi. 4393. 1848. 



Plants up to 5 dm. high, 5 to 7 cm. in diameter, with a large simple or branched tap-root, often 

 12 cm. long; tubercles erect, ascending or widely spreading, very woolly in their axils, bluish green, 

 10 to 12.5 em. long, more or less 3-angled, nearly truncate at apex, gradually dying off below and 

 leaving broad scars on the trunk; spines papery, thin; radial spines 8 to 14, about 5 cm. long; central 

 spines 1 or 2, sometimes 10 cm. long; flowers lasting for several days, fragrant, solitary, from just 

 below the tips of the young tubercles, more or less funnelform, the limb when widely expanded 

 10 cm. broad; outer perianth-segments reddish with a brown stripe down the middle; inner perianth- 

 segments oblong, acute, serrate at apex; stamens and style somewhat exserted; stigma-lobes 9 to 12, 

 linear; fruit probably dry; seeds dark brown, minutely tuberculate. 



Fig. 117 a. Leuchtenbergia principis. 



Type locality: Real del Monte (not Rio del Monte), Hidalgo, Mexico. 



Distribution: Central to northern Mexico. 



Hooker's plant came from Real del Monte, Hidalgo, where it was obtained by John 

 Taylor. This is the only locality cited by Hemsley in the Biologia. It has been reported 

 from the states of San Luis Potosl, Guanajuato, Zacatecas, and Coahuila. This is a wide 

 distribution for the species. We have never seen plants from near the type locality. 



In appearance this plant is very unlike any of the other cacti. Hooker speaks of its 

 resemblance to some aloid plant with stems like those of some cycads. It is said to be used 

 by the Mexicans as a medicine. 



The plant was called by Hooker noble leuchtenbergia and also agave cactus. 



Dr. C. A. Purpus writes that he found this plant in slate and lime formation in the 

 Sierra de la Parras near Parras, Coahuila, and still more abundant in the Sierra de la Paila, 

 also in Coahuila. This last station is a very inaccessible desert mountain range, almost 



