ECHINOCEREUS. 
5 
Key to Species— continued. 
Central spines in more than i row. 
Central spines in a vertical row . 
Ribs strongly tubercled. 
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 . 
Perianth-segments oblong-erose . 
Areoles approximate; spines densely interlocking . 
Stems 3 to 4 cm. thick. 
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. 
Central spine white. 
Central spine, if present, short. 
Spines of ovary and tube of flower slender and weak, the surrounding 
hairs long and cobwebby. 
Spines variegated. 
Spines of one color. 
Spines strongly pectinate and appressed . 
Spines not strongly pectinate, more or less porrect . 
Spines of ovary and tube of flower short and stout, the surrounding 
hairs short. 
Central spine none. 
Stems cylindric . 
Stems globular . 
Central spines present . 
Areoles circular; spines not pectinate. 
Central spines brown, much longer than white radials . 
Central spines not longer than radials. 
Areoles about 5 mm. apart; spines densely interlocking . 
Areoles about 1 cm. apart; spines scarcely interlocking. 
FF. Areoles nearly circular, not so closely set; spines never pectinate. 
Ovary strongly tuberculate . 
Ovary not strongly tuberculate. 
Flowers small, 2.5 to 5 cm. long. 
Plants strongly angled; flower pinkish . 
Plants not strongly angled; flower purple. 
Central spines none. 
Spines 3 to 5; flower-tube and ovary without long wool from 
the areoles . 
Spines 6 to 8; flower-tube and ovary bearing long cobwebby 
wool from the areoles . 
Central spines 1 or more. 
Central spine 1 . 
Central spines several, much elongated, dagger-like. 
Flowers large, 6 to 12 cm. long. 
Central spines none . 
Central spines present. 
Central spine solitary, rarely 2. 
Spines red at base. 
Spines not red at base. 
Plants stout, erect ... . 
Plants weak, becoming prostrate . 
Central spines several. 
Spines never white. 
Spines yellowish brown to red. 
Spines short, usually stout, 10 mm. long. 
Spines, at least some of them, very long. 
Spines bluish to blackish. 
Spines usually white or straw-colored. 
Ribs 7 to 9. 
Ribs 11 to 13. 
Flowers campanulate. 
Flowers short-funnelform. 
AA. Flowers minute, 1.2 cm. long or less. 
AAA. Published species not grouped.■ 
23. E. dasyacanthus 
24. E. ctenoides 
25. E. papillosus 
26. E. blanckii 
27. E. pentalophus 
28. E. sciurus 
29. E. cinerascens 
30. E. adustus 
31. E. standleyi 
32. E. perbettus 
33. E. reichenbacliii 
34. E. baileyi 
35. E. rigidissimus 
36. E. weinbergii 
37. E. pectinalus 
38. E.fitchii 
39. E. scopulorum 
40. E. roetteri 
41. E. chlorophthalmus 
42. E. knippelianus 
43. E. pulchellus 
44. E. amoenus 
45. E. palmer i 
46. E. brandegeei 
47. E. hempelii 
48. E. merkeri 
49. E. fendleri 
50. E. enneacanthus 
51. E. lloydii 
52. E. engelmannii 
53. E. sarissophorus 
54. E. dubiiis 
55. E. conglomeratus 
56. E. stramineus 
57. E. barthelowanns 
58. E. niamillatus 
59. E. ehrenbergii 
60. E. longisetus 
