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). 



Mammillaria sempervivi De Candolle, Mem. Mus. Hist. Nat. Paris 17: 114. 1828. 

 Mammillaria sempervivi tetracantha De Candolle, Mem. Mus. Hist. Nat. Paris 17: 114. 1828. 

 Mammillaria caput-medusae Otto in Pfeiffer, Enum. Cact. 22. 1837. 

 Mammillaria diacanlha Lemaire, Cact. Aliq. Nov. 2. 1838. 



Mammillaria sempervivi laeteviridis Salm-Dyck, Cact. Hort. Dyck. 1849. 113. 1850. 

 Mammillaria caput-medusae centrispina Salm-Dyck in Labouret, Monogr. Cact. 91. 1853. 

 Mammillaria caput-medusae crassior Salm-Dyck in Labouret, Monogr. Cact. 91. 1853. 

 Mammillaria caput-medusae tetracantha Salm-Dyck in Labouret, Monogr. Cact. 91. 1853. 

 Cactus sempervivi Kuntze, Rev. Gen. PI. i: 261. 1891. 



Fig. 79. — Neomammillaria sempervivi. 



Fig. 80. — Neomammillaria 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 CandoUe's illustration. 

 The 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. sempervivi as a 

 synonym of M. caput-medusae. Knippel's illustration of M. caput-medusae (pi. 19) seems 

 to be referable here. Nicholson states that M. caput-medusae is only a form of this species. 



