ECHINOCEREUS. 
KEY TO SPECIES—continued. 
Central spines in more than 1 row. .. 23. 
Central spines in a vertical row. . 24. 
Ribs strongly tubercled. ae . 25. 
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. 
Perianth-segments oblong-erose. . Leen eee .. 27. 
Areoles approximate; spines densely interlocking. .. 28. 
Stems 3 to 4 cm. thick. . ieee eee . 29. 
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. ... 00... 1... ee eee cee cee eee 30. 
Central spine white. . . 31. 
Central spine, if present, short. 
Spines of ovary and tube of flower slender and weak, the surrounding 
hairs ons 8 and  cobwebby. 
Spines variegated. . 
Spines of one color. 
Spines strongly pectinate and appressed..................... 33 
Spines not strongly pectinate, more or less porrect. Lee 34 
Spines of ovary and tube of flower short and stout, the surrounding 
hairs short. 
Central spine none. 
Stems cylindric. . - 35 
Stems globular. . 36 
Central spines present. - . . 37 
Areoles circular; spines not pectinate. 
Central spines brown, much longer than white radials............... 38 
Central spines not longer than radials. 
Areoles about 5 mm. apart; spines densely interlocking. . 39 
Areoles about 1 cm. apart; spines scarcely interlocking. . . 40 
FF. Areoles nearly circular, not so poety set; spines never pectinate. 
Ovary strongly tuberculate. . Leen eee e nett ee eee 41 
Ovary not strongly tuberculate. 
Flowers small, 2.5 to 5 cm. long. 
Plants strongly angled; flower pinkish......................... 42 
Plants not strongly angled; flower purple. 
Central spines none. 
Spines 3 to 5; flower-tube and ovary without long wool from 
the areoles.. ; 43. 
‘Spines 6 to 8; flower- tube and ovary bearing lontg « ‘cobw webby 
wool from the areoles ...... . 44. 
Central spines 1 or more. 
Central spine 1. .. 45. 
Central spines several, much ‘elongated, dagger- jike.. . 46. 
Flowers large, 6 to 12 cm. long. 
Central spines none. . . . 47 
Central spines present. 
Central spine solitary, rarely 2. 
Spines red at base.... 2... 06 eee eee eee eens 48 
Spines not red at base. 
Plants stout, erect.......0 0.0000... e eee eee 49 
Plants weak, becoming prostrate.............. 0.0 ...... 50. 
Central spines several. 
Spines never white. 
Spines yellowish brown to red. 
Spines short, usually stout, ro mm. long............... 51 
Spines, at least some of them, very long............... 52 
Spines bluish to blackish. . sees - 53 
Spines usually white or straw-colored. 
Ribs 7 to 9. 54. 
Ribs 11 to 13. 
Flowers campanulate. ... 0.0.0... .. 000.0 c cee eee ee eee 55. 
Flowers short-funnelform................... 00000000 56. 
AA. Flowers minute, 1.2 cm. long or less. ..... 00... ccc eee cee eee eeeeee 
AAA, Published species not grouped. ..... 0.0... cc cece ec cece ce eee eee eee eee eens 
SP Bh & & 
E. 
E. 
E. 
dasyacanthus 
ctenoides 
papillosus 
blanckii 
. pentalophus 
. SCLUTUS 
. cinerascens 
E. adustus 
E. standleyi 
_E. 
_ E. 
_£, 
_ =z. 
_ E. perbellus 
. E. reichenbachit 
_ E. baileyi 
rigidissimus 
weinbergit 
pectinatus 
_ E. fitchii 
_ =z. 
_ &E, 
scopulorum 
roettert 
. E. chlorophthalmus 
knippelianus 
. pulchellus 
. amoenus 
. palmeri 
. brandegeei 
. hempelii 
. E. merkeri 
. E. fendleri 
E. enneacanthus 
ie 
by ty by by ta ty 
lloydii 
engelmannii 
sarissophorus 
». dubius 
conglomeratus 
Stramineus 
. barthelowanus 
. mamillatus 
. ehrenbergit 
. longisetus 
