54 



THB 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 hiliun 1. E. tuberculosa 



Plants usually globose; seeds larger than in E. tuberculosa, black, with a sub- 

 basal hilum 2. E. dasyacantha 



Flowers small, about 1.5 cm. long. 



Plants globose to stout-cylindric. 



Inner perianth-segments pointed. 



Inner perianth-segments broad 3. E. chihuahuensis 



Inner perianth-segments narrow 4. E. runyonii 



Inner perianth-segments obtuse 5 . E. chaff eyi 



Plants slender-cylindric 6. E. sneedii 



Groove of tubercles with glands 7. E. bella 



Outer perianth-segments eciliate 8. E. lloydii 



1. Escobaria tuberculosa (Engelmann). 



Mamtnillaria strobiliformis Scheer in Salm-Dyck, Cact. Hort. Dyck. 1849. 104. 1850. Not Engelmann, 



1848. 

 Echinocactiis strobiliformis Poselger, Allg. Gartenz. 21: 107. 1853. 

 Mammillaria tuberculosa Engelmann, Proc. Amer. Acad. 3: 268. 1856. 

 Cactus tuherculosus Kuntze, Rev. Gen. PI. i: 261. 1891. 

 Cactus strobiliformis Kuntze, Rev. Gen. PI. i: 261. 1891. 



Mammillaria strobiliformis pubescens Quehl, Monatsschr. Kakteenk. 17: 87. 1907. 

 Mammillaria strobiliformis durispina Quehl, Monatsschr. Kakteenk. 17: 87. 1907. 

 Mammillaria strobiliformis rufispina Quehl, Monatsschr. Kakteenk. 17: 87. 1907. 

 Mammillaria strobiliformis caespititia Quehl, Monatsschr. Kakteenk. ig: 173. 1909. 







Fig. 51. — Escobaria tuberculosa. 



Fig. 52. — Escobaria dasyacantha. 



Usually growing in clumps, cj'lindric 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 Coryphaniha tuberculosa occurs in C. R. Orcutt's Circular to Cactus Fanciers, 

 1922. 



