STANDLEY TEEES AND SHRUBS OF MEXICO. 959 



10. Thelocactus lloydii Britt. & Rose, Cactaceae 4: 11. 1923. 

 Zacatecas. 



Plants simple, depressed-globose, 8 to 12 cm. broad, pale bluish green, 

 strongly tubercled and strongly armed; tubercles conspicuous but low, often 

 wider than long, sometimes 4 cm. wide ; flowering groove rather conspicuous 

 but narrow, extending from the spines halfway to the axil of the tubercle ; 

 spines usually 8, sometimes with a smaller accessory one, all ascending from 

 the base and curved outward from the center, terete or somewhat angled at 

 base, often highly colored below, with sharp yellowish crimson tips, the 

 longer ones 6 cm. long; outer perianth segments very pale purple. 



11. Thelocactus bicoror (Galeotti) Britt. & Rose, Bull, Torrey Club 49: 251. 

 1022. 



Echinocactus bicolor Galeotti; Pfeiff. Abbild. Beschr. Cact. 2: pi. 25. 1848. 



Echinocactus rlwdophthahmis Hook, in Curtis's Bot. Mag. 76: pi. i486. 1850. 



EcMnocacUis ellipticus Lem. Jard. Fleur. 3: pi. 210. 1853. 



Echinocactus Tjolansis Riinge, Gartenfiora 38: 106. 1SS9. 



Central and eastern Mexico. Texas. 



Plants simple, globose to conic, glaucous, small, up to 3 cm. high, very 

 spiny ; ribs usually 8, broad, somewhat tubercled ; ar^oles approximate ; spines 

 highly, colored, sometimes bright red or yellowish or red and yellow; radial 

 spines 9 to 18, widely spreading or sometimes bent backward at tip. 8 cm. long 

 or less; central spines usually 4, ascending or porrect, all straight, 3 to 5 

 cm. long, subulate; flowers 5 to 6 cm. long and fully as broad when ex- 

 panded ; outer perianth segments pale purple, the inner ones deep purplish 

 pink, oblong, acute; scales on ovary and flower tube imbricate, ovate, with 

 scarious and ciliate margins; fruit about 1 cm. long, dehiscing by a large 

 irregular basal opening; seeds 2 mm. long, black. 



12. Thelocactus pottsii (Salm-Dyck) Britt. & Rose, Cactaceae 4: 12. 1923. 

 Echinocactus pottsii Salm-Dyck, Allg. Gartenz. 18: 395. 1850. 

 Echinocactus heterochromiis "Weber, Diet. Hort. Bois 466. 1896. 

 Chihuahua and Coahuila ; type from Chihuahua City. 



Globular or somewhat depressed, 10 to 15 cm. in diameter, somewhat 

 glaucous, yellowish ; ribs 8 or 9, broad and obtuse, more or less distinctly 

 tubercled ; areoles large, closely set on old plants, densely felted when young, 

 naked in age; spnes variable as to number, shape, size, and color; radial 

 spines 7 to 10, acicular, usually terete, straight or incurved, more or less 

 banded with red and white or pale yellow, 1 to 3 cm. long; central spines 

 several, stout-subulate, more or less flattened, 3 to 4 cm. long, often white, 

 sometimes banded with red ; flowers 5 to 6 cm. long ; scales on ovary and 

 flower tube ovate, greenish, the margins thin and ciliate; inner perianth 

 segments light purple, darker at base, oblong; fruit globose, 1.5 cm. in diam- 

 eter ; seeds tuberculate, black. 



41. NEOLLOYDIA Britt. & Rose, Bull. Torrey Club 49: 251. 1922. 



Small, more or less cespitose cacti, fibrous-rooted, cylindric, densely spiny, 

 tubercled ; tubercles more or less arranged on spiraled ribs, grooved above ; 

 radial spines numerous, widely spreading; central spines one to several, much 

 stouter and longer than the radials ; flowers large, pink or purple, subcentral 

 from the axils of nascent tubercles, their segments widely spreading; fruit 



