108 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 Echinocactus 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 
Mamamiillaria. 
>1. Leuchtenbergia principis Hooker in Curtis’s Bot. Mag. 74: pl. 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 cm. 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 I 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. 
Fic. 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 Potosi, 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 
