i88 
THE CACTACEAE. 
Key to Species— continued. 
Central spines definitely longer than the radials. 
Spines strongly curved. 
Spines straight. 
Inner perianth-segments about i cm. long. 
ED. Flowers salmon or red. 
Ribs about 13, obtuse; flowers salmon. 
Ribs 30 or more, acutish; flowers red. 
CC. Spines elongated, the central ones 1.5 to 7 cm. long, curved; flowers orange-red. . 
BB. Areoles of ovary and flower-tube with tufts of short hairs. 
Spines stout, subulate. 
Spines slender, acicular. 
Spines long, much curved. 
Spines short, nearly straight. 
AA. Plants becoming slender-cylindric and much elongated. 
AAA. Species not grouped. 
18. 
19 - 
20. 
21. 
22. 
23- 
24. 
25. 
26. 
27. 
/28. 
I29. 
M. langsdorffii 
M. mammulosus 
M. islayensis 
M. strausianus 
M. haselbergii 
M. maassii 
M. tuberisulcatus 
M. curoispinus 
M. mammillarioides 
M. leninghausii 
M. graessneri 
M. escayachensis 
1 . Malacocarpus tephracanthus (Link and Otto) Schumann, FI. Bras. 4 2 : 243. 1890. 
Echinocartus tephracanthus Link and Otto, Yerh. Yer. Beford. Gartenb. 3: 422. 1827. 
Echinocactus acuatus* Link and Otto, Yerh. Yer. Beford. Gartenb. 3: 424. 1827. 
Echinocactus sellowii Link and Otto, Yerh. Yer. Beford. Gartenb. 3: 425. 1827. 
Melocactus tephracanthus Link and Otto, Yerh. Ver. Beford. Gartenb. 3: pi. 16, f. 2. 1S27. 
Melocactus sellowii Link and Otto, Yerh. Yer. Beford. Gartenb. 3: pi. 22. 1827. 
Melocactus acuatus Link and Otto, Yerh. Yer. 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 tetracanthus 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 Salm-Dyck, Cact. Hort. Dyck. 1849. 25. 1850. 
Malacocarpus sellowianus tetracanthus Salm-Dyck, Cact. Hort. Dyck. 1849. 25. 1850. 
Malacocarpus courantii Salm-Dyck, Cact. Hort. Dj*ck. 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 Riimpler in Forster, Handb. Cact. ed. 2. 454. 1885. 
Malacocarpus sellowii Schumann, FI. Bras. 4 2 : 238. 1S90. 
Malacocarpus sellowii tetracanthus Schumann, FI. Bras. 4 2 : 239. 1890. 
Malacocarpus tetracanthus Meyer, Monatsschr. Kakteenk. 4; 143. 1894. 
Echinocactus sellowii martinii Schumann, Gesamtb. Kakteen 297. 1S98. 
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. 1905. 
Echinocactus sellowii macrocanthus Arechavaleta, Anal. Mus. Nac. Montevideo 5: 230. 1905. 
Echinocactus sellowii macrogonus Arechavaleta, Anal. Mus. Nac. Montevideo 5: 232. 1905. 
Echinocactus sellowii acutatus Arechavaleta, Anal. Mus. Nac. Montevideo 5: 234. 1905. 
Echinocactus sellowii turbinatus 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 Giirke, Monatsschr. Kakteenk. 18: 149. 1908. 
Echinocactus sellowii typicus Gurke, Monatsschr. Kakteenk. 18: 149. 1908. 
Simple, globular or somewhat depressed, up to 15 cm. 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 L T ruguay. 
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 acutatus and Melocactus acutatus. Don (Gen. Syst. 3: 163. 1834) writes the name E. arcuatus. 
