I 66 THE CACTACEAE. 



Mammillaria diacentra Jacobi, Allg. Gartenz. 24: 91. 1856. 



Globose, about 7 cm. in diameter; tubercles milky, rhomboid at base, not setose in their axils; 

 radial spines 5 or 6, white, with blackish tips; central spines 2, stouter and longer than the radials, 

 grayish, with blackish tips, the lower centrals 2.5 cm. long or more; flowers small, reddish; style 

 rose-colored: stigma-lobes 6. 



This species was unknown to Schumann, and we are unable to group it; its origin is 

 not recorded. 



MammiIvLaria FLAvescENS Haworth, Suppl. PL Succ. 71. 1819. 



Cactus mammillaris lanuginosiis De CandoUe, PI. Succ. in. 1799. 

 Cactus flavescens De CandoUe, Cat. Hort. Monosp. 83. 1813. 

 Mammillaria straminea Haworth, Suppl. PI. Succ. 71. 1819. 

 Cactus stramineus Sprengel, Syst. 2: 494. 1825, as to name. 

 Mammillaria simplex flavescens Schumann, Gesamtb. ^akteen 573. 1898. 



This plant was first described in 1799 by De CandoUe as "var. j8" of Cactus mam- 

 millaris or Cactus mammillaris lanuginosus (PI. Succ. pi. iii); at this time he referred 

 to it certain citations of Plumier and Hermann which we now know belong to Neomammil- 

 laria prolifera and N. mammillaris respectively. This variety was raised to specific rank 

 by De CandoUe in 1813 as Cactus flavescens (Cact. Hort. Monosp. 83). From the more 

 detailed description then given it is clear that Cactus flavescens can not be referred to 

 either N. prolifera or A''. m.ammillaris . It was transferred to the genus Mammillaria by 

 Haworth in 1819, but he added little information except the statement that it had been 

 in cultivation in the Chelsea Garden before 1811. 



The question has been raised whether this plant is really West Indian. It is true that 

 De CandoUe does not state its origin, but it would be indicated that he believed that it was 

 West Indian by his treating it as a variety of the common West Indian species and by his 

 referring to it several West Indian descriptions when he later published it as a species. 

 Pfeiffer states that it is tropical American. As Neomammillaria mammillaris is the only 

 species known from South America it could not have come from that continent, and at 

 that time no Mammillaria had been discovered in the United States or Mexico. Forster 

 • n 1846 says that it is West Indian, and this was Schumann's conclusion. 



Mammillaria flavicoma Hortus in Forster, Handb. Cact. ed. 2. 298. 1885. 



This species was described from garden plants of unknown origin. Schumann does not 

 mention it in his monograph and it has remained unknown. 



Mammillaria grisea Salm-Dyck, Cact. Hort. Dyck. 1849. no. 1850. 

 Cactus griseus Kuntze, Rev. Gen. PI. i: 260. 1891. 



Stout, short-cylindric, 10 to 12.5 cm. high, 7.5 cm. in diameter; tubercles glaucous-green, 

 somewhat 4-angled, their axils woolly and setose; radial spines 10 to 12, spreading, short, rigid, 

 white; central spines 4 to 6, white, with brown or blackish tips, on greenhouse plants 10 to 15 mm. 

 long, but on wild plants 5 cm. long or more; flower and fruit unknown. 



This is perhaps different from Mammillaria grisea Galeotti (Forster, Handb. Cact. 

 219. 1846), which was never described. 



Mammillaria HEiNEi Fhrenberg, Bot. Zeit. 2: 833. 1844. 

 Cactus heinei Kuntze, Rev. Gen. PI. i: 260. 1891. 



Schumann thought that this name was referable to Mammillaria umbrina but we have 

 not been able to satisfy ourselves that the two are the same. 



Much confusion is found in the spelling of the name; it sometimes appears as M. 

 haynii and M. haynei. Salm-Dyck transfers two species of Khrenberg to varieties of M. 

 haynii but both are unknown to us. These varieties are as follows : var. viridula Salm-Dyck 

 (Cact. Hort. Dyck. 1849. 10. 1850; M. viridula Ehrenberg, Allg. Gartenz. 16: 267. 



