I 88 THE CACTACEAE. 



Key to Species continued. 



Central spines definitely longer than the radials. 



Spines strongly curved 18. M. langsdorffii 



Spines straight 19. M. mammulosus 



Inner perianth-segments about 1 cm. long 20. M. islayensis 



DD. Flowers salmon or red. 



Ribs about 13, obtuse; flowers salmon 21. M. strausianus 



Ribs 30 or more, acutish; flowers red 22. M. haselbergii 



CC. Spines elongated, the central ones 1.5 to 7 cm. long, curved; flowers orange-red. . 23. M. maassii 



BB. Areoles of ovary and flower-tube with tufts of short hairs. 



Spines stout, subulate 24. M. tuberisulcahis 



Spines slender, acicular. 



Spines long, much curved 25. M. curvispinus 



Spines short, nearly straight 26. M. mammillarioides 



AA. Plants becoming slender-cylindric and much elongated 27. M. leninghausii 



. . . , (28. M. graessneri 



AAA. Species not grouped | 2g M _ % scayachenils 



1. Malacocarpus tephracanthus (Link and Otto) Schumann, Fl. Bras. 4 2 : 243. 1890. 



Echinocactus tephracanthus Link and Otto, Verh. Ver. Beford. Gartenb. 3: 422. 1827. . 



Echinocactus acuatits* Link and Otto, Verh. Ver. Beford. Gartenb. 3: 424. 1827. 



Echinocactus sellowii Link and Otto, Verh. Ver. Beford. Gartenb. 3: 425. 1827. 



Melocactus tephracanthus Link and Otto, Verh. Ver. Beford. Gartenb. 3: pi. 16, f. 2. 1827. 



Melocactus sellowii Link and Otto, Verh. Ver. Beford. Gartenb. 3: pi. 22. 1827. 



Melocactus acuatus Link and Otto, Verh. Ver. Beford. Gartenb. 3: pi. 23. 1827. 



Echinocactus sellowianus Pfeiffer, Enum. Cact. 55. 1837. 



Echinocactus sessiliflorus Mackie in Curtis's Bot. Mag. 64: pi. 3569. 1837. 



Echinocactus tetracauthus Lemaire, Cact. Aliq. Nov. 15. 1838. 



Echinocactus courantii Lemaire, Cact. Aliq. Nov. 20. 1838. 



Echinocactus sessiliflorus pallidas Monville in Lemaire, Cact. Gen. Nov. Sp. 88. 1839. 



Echinocactus sessiliflorus tetracanthus Monville in Lemaire, Cact. Gen. Nov. Sp. 88. 1839. 



Cereus tephracanthus Steudel, Nom. ed. 2. 1: 336. 1840. 



Malacocarpus sellowianus Salrn-Dyck, Cact. Hort. Dyck. 1849. 25. 1850. 



Malacocarpus sellowianus tetracanthus Salm-Dyck, Cact. Hort. Dyck. 1849. 25. 1850. 



Malacocarpus courantii Salm-Dyck, Cact. Hort. Dyck. 1849. 25. 1850. 



Echinocactus tephracanthus spinosior Labouret, Monogr. Cact. 171. 1853. 



Echinocactus courantii spinosior Monville in Labouret, Monogr. Cact. 171. 1853. 



Echinocactus sellowianus tetracanthus Labouret, Monogr. Cact. 172. 1853. 



Malacocarpus martinii Rumpler in Forster, Handb. Cact. ed. 2. 454. 1885. 



Malacocarpus sellowii Schumann, Fl. Bras. 4 2 : 238. 1890. 



Malacocarpus sellowii tetracanthus Schumann, Fl. Bras. 4 2 : 239. 1890. 



Malacocarpus tetracanthus Meyer, Monatsschr. Kakteenk. 4: 143. 1894. 



Echinocactus sellowii martinii Schumann, Gesamtb. Kakteen 297. 1898. 



Echinocactus acuatus sellowii Spegazzini, Anal. Mus. Nac. Buenos Aires III. 4: 494. 1905. 



Echinocactus acuatus tetracanthus Spegazzini, Anal. Mus. Nac. Buenos Aires III. 4: 494. i95- 



Echinocactus sellowii macrocanthus Arechavaleta, Anal. Mus. Nac. Montevideo 5: 230. 1905. 



Echinocactus sellowii macrogonus Arechavaleta, Anal. Mus. Nac. Montevideo 5: 232. 1905. 



Echinocactus sellowii acutalus Arechavaleta, Anal. Mus. Nac. Montevideo 5: 234. 1905. 



Echinocactus sellowii lurbinatus Arechavaleta, Anal. Mus. Nac. Montevideo 5: 235. 1905. 



Echinocactus fricii Arechavaleta, Anal. Mus. Nac. Montevideo 5: 244. 1905. 



Echinocactus pauciareolatus Arechavaleta, Anal. Mus. Nac. Montevideo 5: 246. 1905. 



Echinocactus sellowii courantii Gtirke, Monatsschr. Kakteenk. 18: 149. 1908. 



Echinocactus sellowii typicus Giirke, Monatsschr. Kakteenk. 18: 149. 1908. 



Simple, globular or somewhat depressed, up to 15 em. in diameter, woolly at apex; ribs 18 to 22, 

 acute, rather high, hardly undulate on the margin, light green; areoles 1.5 to 2 cm. apart; spines 4 to 

 6, straight or curved backward, the longest 2 cm. long; flowers from the woolly apex of the plant, 

 4 to 4.5 cm. long, broader than long when fully expanded; perianth-segments yellow, narrowly ob- 

 long, mucronate-tipped; stamens and style slightly exserted; stigma-lobes red; perianth deciduous; 

 fruit small, 1 cm. long, purple, fleshy, scaly; scales ovate, bearing hairs and bristles in their axils; 

 seeds black, 1 mm. long. 



Type locality: "Rio Grande," perhaps better, Rio Grande do Sul, Brazil. 



Distribution: Brazil, Argentina, and Uruguay. 



Walpers (Repert. Bot. 2: 275. 1843) referred Echinocactus acuatus spinosior Lemaire to 

 E. courantii. This variety was not described, however, until 1839 when Lemaire (Cact. 

 Gen. Nov. Sp. 87. 1839) assigned it to Monville and referred to it, as a synonym, Echino- 

 cactus suberinaceus Lemaire. 



*The specific name was originally given by Link and Otto as above, but Schumann changed it, writing both 

 Echinocactus acutalus and Melocactus acutalus. Don (Gen. Syst. 3: 163. 1834) writes the name E. arcualus. 



