86 THE CACTACEAE. 
Mammillaria flavovirens cristata Salm-Dyck (Cact. Hort. Dyck. 1849. 16. 1850) is 
only a name. 
The name Mammillaria daedalea viridis Fennel is given by Labouret (Monogr. Cact. 
100. 1853) as a synonym of M. flavovirens. 
/ 26. Neomammillaria sempervivi (De Candolle). 
Fic. 79.—Neomammillaria sempervivi. Fic. 80.—Neomammnillaria polythele. 
Solitary or somewhat cespitose, flattened above, narrowed below; axils of tubercles very woolly ; 
tubercles short, milky, angled; spine-areoles very woolly when young, but glabrate in age; radial 
spines 3 to 7, short, white, caducous; central spines 2, ascending, brownish, stoutish; flowers dull 
white with reddish lines; inner perianth-segments acute, spreading. 
Type locality: Mexico. 
Distribution: Central Mexico. . 
Dr. Rose collected what he took to be this species in the Barranca Sierra de la Mesa, 
Hidalgo, Mexico, in 1905, but this plant differs somewhat from De Candolle’s illustration. 
T he central spines, while generally 2, are sometimes 3 and are not so stout; the radial 
spines are deciduous, as they should be in this species. It flowered once at Washington. 
An examination of the original description of Mammillaria caput-medusae suggests the 
probability that this species is identical with Mammillaria sempervivi. The two names 
appeared in collections in 1829 and may have come from a common source. Indeed, 
Schumann credits T. Coulter with having obtained M. caput-medusae, while we know that 
M. sempervivi was based on Coulter’s plant and, then, too, Pfeiffer refers M. sempervivt as a 
synonym of M. caput-medusae. Knippel’s illustration of M . caput-medusae (pl. 19) seems 
to be referable here. Nicholson states that V. caput-medusae is only a form of this species. 
