54 THE CACTACEAE. 
KEY TO SPECIES. 
Outer perianth-segments ciliate. 
Groove of tubercles without glands. 
Flowers large for the genus, 2 to 2.5 cm. long. 
Plants elongated; seeds very small, brown, with ventral hilum 
Plants usually globose; seeds larger than in E. tuberculosa, black, with a sub- 
& 
. tuberculosa 
basal hilum......... 0.00 ee ene net eens 2. E. dasyacantha 
Flowers small, about 1.5 cm. long. 
Plants globose to stout-cylindric. 
Inner perianth-segments pointed. 
Inner perianth-segments broad.............-- 0500s e eee eee eee 3. E. chihuahuensis 
Inner perianth-segments narrow..........--.- 05-05 t eee eee eee 4. E. runyonu 
Inner perianth-segments obtuse...... 0... 6.60.5 e eee eee eee 5. E. chaffeyt 
Plants slender-cylindric..........0. 6 eee eee eee ees 6. E. sneedu 
Groove of tubercles with glands. .......... 00.0 e cee eee eee 7. E. bella 
Outer perianth-segments eciliate... 0.0.66. eee nett es 8. E. lloydit 
> 1. Escobaria tuberculosa (Engelmann). 
»Mammillaria strobiliformis Scheer in Salm-Dyck, Cact. Hort. Dyck. 1849. 104. 1850. Not Engelmann, 
1848. 
Echinocactus strobiliformis Poselger, Allg. Gartenz. 21: 107. 1853. 
S Mammillaria tuberculosa Engelmann, Proc. Amer. Acad. 3: 268. 1856. 
Cactus tuberculosus Kuntze, Rev. Gen. Pl. 1: 261. 1891. 
Cactus strobiliformis Kuntze, Rev. Gen. Pl. 1: 261. 1891. 
Mammillaria strobiliformis pubescens Quehl, Monatsschr. Kakteenk. 17: 87. 1907. 
Mamamnillaria strobiliformis durispina Quehl, Monatsschr. Kakteenk. 17: 87. 1907. 
Mammillaria strobiliformis rufispina Quehl, Monatsschr. Kakteenk. 17: 87. 1907. 
Mammnillaria strobiliformis caespititia Quehl, Monatsschr. Kakteenk. 19: 173. 1909. 
Fic. 51.—Escobaria tuberculosa. 
Fic. 52.—Escobaria dasyacantha. 
Usually growing in clumps, cylindric or becoming so, 5 to 18 cm. high, 2 to 6 cm. in diameter; 
tubercles more or less regularly arranged in spirals, 6 mm. long; radial spines numerous, white, 
sometimes as many as 30, acicular, 4 to 15 mm. long; central spines several, stouter than radials, 
brown to blackish or colored only at tips, one of them usually porrect; flowers 2.5 cm. in diameter 
when fully expanded, light pink; outer perianth-segments acute, ciliate; inner perianth-segments 
narrowly pointed; fruit oblong, up to 20 mm. long, red; seeds pitted, with a small ventral hilum. 
Type locality: Mountains near El Paso and eastward. 
Distribution: Southwestern Texas, southern New Mexico, and adjacent Mexico. 
Flowers appear in the afternoon and last for two days at least. 
The name Coryphantha tuberculosa occurs in C. R. Orcutt’s Circular to Cactus Fanciers, 
1922. . 
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