ECHINOCEREUS. 



Key to Species continued. 



Central spines in more than i row 23. E. dasyacanthus 



Central spines in a vertical row 24. E. clenoides 



Ribs strongly tubercled 25. E. papillosus 



DD. Flowers purple. 



E. Stems weak, slender, and creeping. 

 Stems 2 cm. thick or less. 



Areoles distant; spines not interlocking. 



Perianth-segments narrowly oblong or linear-oblanceolate 26. E. blancku 



Perianth-segments oblong-erose 27. E. pentalophus 



Areoles approximate; spines densely interlocking 28. E. sciurus 



Stems 3 to 4 cm. thick 29. E. cinerascens 



EE. Stems stout, usually erect or ascending. 



F. Areoles elliptic to circular, closely set, often with pectinate spines. 

 Areoles elliptic; spines pectinate. 

 Central spine often very long. 



Central spine dark 30. E. adustus 



Central spine white 3 1 . E. standleyi 



Central spine, if present, short. 



Spines of ovary and tube of flower slender and weak, the surrounding 

 hairs long and cobwebby. 



Spines variegated 2,2. E. perbellus 



Spines of one color. 



Spines stronglv pectinate and appressed 33. E. reichenbachu 



Spines not strongly pectinate, more or less porrect 34. E. baileyi 



Spines of ovary and tube of flower short and stout, the surrounding 

 hairs short. 

 Central spine none. 



Stems cylindric 35- E. rigidissimus 



Stems globular 36. E. weinbergii 



Central spines present 37- E. pectinatus 



Areoles circular; spines not pectinate. 



Central spines brown, much longer than white radials 38. E.fitchii 



Central spines not longer than radials. 



Areoles about 5 mm. apart; spines densely interlocking 30- E. scopulorum 



Areoles about 1 cm. apart; spines scarcely interlocking 40. E. roetteri 



FF. Areoles nearly circular, not so closely set; spines never pectinate. 



Ovary strongly tuberculate 41. . chlorophlhalmus 



Ovary not strongly tuberculate. 

 Flowers small, 2.5 to 5 cm. long. 



Plants strongly angled; flower pinkish 42. E. kmppehanus 



Plants not strongly angled; flower purple. 

 Central spines none. 



Spines 3 to 5 ; flower-tube and ovary without long wool from 



the areoles 43- E. pulckellus 



Spines 6 to 8; flower-tube and ovary bearing long cobwebby 



wool from the areoles 44- E. amoenus 



Central spines 1 or more. 



Central spine 1 45- E. palmeri 



Central spines several, much elongated, dagger-like 46. E. brandegeei 



Flowers large, 6 to 1 2 cm. long. 



Central spines none 47- E. hempeln 



Central spines present. 



Central spine solitary, rarely 2. . 



Spines red at base 4- E. merken 



Spines not red at base. . 



Plants stout, erect 49- E. fendlen 



Plants weak, becoming prostrate 50. E. enneacanthus 



Central spines several. 

 Spines never white. 



Spines yellowish brown to red. 



Spines short, usually stout, 10 mm. long 51. E. Uoydu 



Spines, at least some of them, very long 52. E. engelmannn 



Spines bluish to blackish 53- E. sanssophorns 



Spines usually white or straw-colored. 



Ribs 7 to 9 54- E. dubius 



Ribs 11 to 13- , 



Flowers campanulate 55- E. conglomerate 



Flowers short-funnelform 56. E. straminens 



AA. Flowers minute, :,2 cm. long or less f SBST 



AAA. Published species not grouped fe f SSff 



