4 THE CACTACEAE. 
In habit it simulates the South American genus, Echinopsis, while in flowers and fruits 
it comes near Erdisia, Bergerocactus, and Wilcoxia. While all the species are low in habit 
there is great variation in the manner and form of growth. Some are solitary ; others grow 
in flat masses, and others in large rounded mounds. The flowers, while always having 
a spiny ovary and flower-tube and green stigma-lobes, have considerable variation in 
the shape and color of perianth-segments and in duration. The flower-buds as well as 
the young shoots are deep-seated in their origin and do not appear just at the areoles as 
in most cacti and hence must break through the epidermis when they develop. A some- 
what similar result is produced in the flowering of some of the species of Rhipsalis. Echino- 
cereus has been selected as the state flower of New Mexico. 
Most plants of Echinocereus do not flower frequently in greenhouse cultivation. 
The species are not readily grouped into series; our classification of them is largely 
artificial, taking flower-color as a more important character than it probably is in nature. 
KEY TO SPECIES. 
A. Flowers large, usually conspicuous, rarely only 2 to 3 cm. long. 
B. Stems covered with long weak bristles or hairs, resembling a small plant of Ceph- 
alocereus YT 
BB. Stems variously covered with spines or rarely spineless, never like the above. 
C. Flowers scarlet to salmon-colored, opening once, but lasting for several days. 
Stems usually weak, often trailing, or at least becoming prostrate; ribs nearly con- 
tinuous. 
Flowers rosy red... 0.0... cece eee e cece ee be ec cece ecco oe. 2. E. scheeri 
Flowers orange-red to salmon-colored. 
Flowers 8 to 11 cm. long; wool from areoles on flower-tube long. 
1. E. delaetti 
Flowers 8 to 10 cm. long; radial spines 9 or fewer......................... 3. E. salm-dyckianus 
Flowers 11 cm. long; radial spines 10 tO 12.........0......0.0.000.0.... .. 4. E. huitcholensis 
Flowers 6 cm. long or less; wool from areoles on flowers shorter than subtending 
seale..... Lee eee . 
wt ence e rece eeeetcecenees 5. E. pensilis 
Stems usually erect and stout; ribs more or less tubercled. 
Plants forming large mounds, sometimes with 500 to 800 joints; spines white, long 
. and flexuous....... Dee eee eee eee eee eee eee e ees 6. E. mojavensis 
Plants in much smaller clusters; spines brownich or grayish, not long and flexuous. 
Plant body with 12 to 14 ribs... 20... 7. E. leeanus 
Plant body with 5 to 11 ribs (in one species 12). 
Ribs 5 to8.......................... . 
8. E. triglochidiatus 
Ribs 9 to 12. 
Axils of flower-scales filled with long cobwebby hairs. 
Flowers 5 to 6 cm. long; spines yellowish at first. __. tteeeeeeeeeeeesee. 9. E. polyacanthus 
Flowers 3 cm. long; spines reddish at first... 22s. to. E. pacificus 
Axils of flower-scales bearing short hairs. 
Stems elongated and thinner than in E. octacanthus................... 11. E. acifer 
Stems short and thicker than in E. acifer. 
Stems pure green when old; centralspiner............... 12. E. octacanthus 
Stems bluish green; central spines several. 
Central spines 6; petals acutish. re 13. E. neo-mexicanus 
Central spines mostly 4, sometimes 3 or 5. 
Central spines more or less angled, somewhat curved............ 14. E. conoideus 
Central spines terete, straight. 
Central spines white or Straw-colored........................ 15. E. coccineus 
Central spines gray to pinkish. . __ bitte eee eee eee eee ee see. 16. E. rosei 
CC. Flowers broad, rotate to campanulate, opening in sunlight, closing at night, usually 
purple, sometimes yellow or greenish yellow, rarely pink or 
nearly white, unknown in E. standleyi. 
D. Flowers yellow or greenish white, 
Ribs not strongly tubercled. 
ants densely cespitose....................... ’ itt 
Plants usucily sites eee ce ee cece eee eee eee 17. E. maritimus 
Ribs very stout. 
Ribs 5 to 8; spines on fower-tube and ovary short............. .. .. 18. E. subinermis 
. 10S © OF 9; spines on flower-tube and ov i 
Ribs low, usually hidden by che spines Ovary acicular.................. 19. E. luteus 
Flowers small, 2.5 cm. long or less. ' 
reoles circular... 
Areoles elliptic... 00.0000) “ E indore 
Flowers large, 5 to 10 cm. long. Romar tae. a 
Flowers greenish white........... 
Flowers yellow-red, TTT ttt tees cee ee sees en eeens 22. E. grandis 
