4 THE CACTACEAE. 
The generic name is from ayxiotpov fish-hook, and x&xros cactus, referring to the 
long, hooked central spines. 
Ancistrocactus was used by Schumann for a subgenus of Echinocactus. We recognize 
three species in the genus, occurring in southern Texas and northern Mexico. 
Coulter (Contr. U. S. Nat. Herb. 3: 368, 369) calls attention to grooved areoles of 
Echinocactus brevihamatus resembling those of Coryphantha and Echinocactus scheert. 
KEY TO SPECIES. 
Radial spines 20 or more, strongly appressed, pectinate; flowering areolesnaked.......... 1. A. megarhizus 
Radial spines 18 or fewer, more or less spreading, hardly pectinate; flowering areoles woolly. 
Groove half length of tubercle; flower greenish; radial spines 15 to 18.............. 2. A. scheert 
Groove extending full length of tubercle; flower rose-colored; radial spines usually 12. 3. A. brevihamatus 
1. Ancistrocactus megarhizus (Rose). 
Echinocactus megarhizus Rose, Contr. U. S. Nat. Herb. 12: 290. 1909. 
Solitary or in clusters of 3 or 4; plant body nearly globular or a little elongated, 5 to 8 cm. high, 
usually solitary, from large and fleshy roots; ribs spiral, divided into dark-green tubercl-s, 4 to 5 
fe Pe i 
Fic. 1.—Ancistrocactus megarhizus. 
cm. high; radial spines 20 or more, pectinate, at first pale yellow, in age white; in seedlings the 
spines pubescent; central spines usually 4, the 3 upper similar to the radials, although a little stouter 
and in young areoles not easily distinguished from them, the lower central spines stout and strongly 
hooked, 15 mm. long; flowers not seen ; fruit green, suggesting that of a C i 
a few naked scales near top; seed black, smooth, shining, MAE OF 8 Coryphantlia, clavate, Dearing 
Type locality: Near Victoria, Mexico. 
Distribution: Known only from the type locality. 
mame eure 1 is from a photograph of the type specimen collected by Dr. Edward 
er. 
2. Ancistrocactus scheeri (Salm-Dyck). 
Echinocactus scheeri * Salm-Dyck, Cact. Hort. Dyck. 1849. 155. 1850. 
Globular to clavate, 3.5 to 5 cm. long: ri indisti . 
_ » 3. - long; ribs usually 13, indistinct, somewhat spiraled, strong! 
divided into stout, terete tubercles grooved only to middle; radial spines 15 to 3 sprea ding, iad 
* This name was originally spelled Echinocactus Scheerit. 
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