Solitary (or nearly so) Agave species

A while back I was asked if I had a list of agave species that are solitary or nearly so. I have called on my friends at agaveville.org to help develop such a list which is presented here. The main criterion being that the species should be solitary or nearly so in habitat since cultivation can cause some wackiness in the plants. Also, only species from Continental North America, so the Caribbean and South American ones are out and no hybrids allowed.

1. Agave angustiarum
2. Agave arcedianoensis
3. Agave atrovirens
4. Agave aurea subsp. aurea
5. Agave aurea subsp. promontorii
6. Agave azurea
7. Agave bakeri
8. Agave bovicornuta
9. Agave chazaroi
10. Agave chrysantha
11. Agave chrysoglossa (mostly)
12. Agave colimana
13. Agave congesta
14. Agave convallis
15. Agave cupreata
16. Agave deserti subsp. simplex
17. Agave dasylirioides
18. Agave durangensis
19. Agave garcia-mendozae
20. Agave geminiflora
21. Agave gigantensis (not the imposter A. sobria)
22. Agave guadalajarana
23. Agave guiengola (mostly)
24. Agave hiemiflora
25. Agave hookeri
26. Agave horrida
27. Agave hurteri
28. Agave impressa
29. Agave inaequidens
30. Agave jaiboli
31. Agave kerchovei
32. Agave lagunae
33. Agave marmorata
34. Agave maximiliana
35. Agave montana
36. Agave moranii
37. Agave multifilifera
38. Agave nayaritensis
39. Agave nuusaviorum
40. Agave ocahui
41. Agave ornithobroma
42. Agave pachycentra
43. Agave palmeri
44. Agave parvidentata
45. Agave pedunculifera
46. Agave pelona
47. Agave pendula
48. Agave polianthiflora
49. Agave potatorum
50. Agave potrerana
51. Agave scaposa
52. Agave schidigera
53. Agave seemaniana
54. Agave shrevei
55. Agave temacapulinensis
56. Agave thomasae
57. Agave titanota
58. Agave turneri
59. Agave utahensis subsp. kaibabensis
60. Agave vazquezgarciae
61. Agave vilmoriniana
62. Agave wendtii
63. Agave wercklei
64. Agave wocomahi
65. Agave xylonacantha
66. Agave zebra