| Entry | Volume | Pages |
|---|---|---|
| Senior, Robert M.: Annual Campanulas of Syria and Palestine | 16 | 208 |
| Senior, Robert M.: Attractive Rocky Mountain Plants | 22 | 66 |
| Senior, Robert M.: Campanula aurita | 18 | 208 |
| Senior, Robert M.: Campanula mollis | 13 | 10 |
| Senior, Robert M.: Campanula pelia | 12 | 106 |
| Senior, Robert M.: Campanula Queries | 9 | 138 |
| Senior, Robert M.: Craters of the Moon | 30 | 260 |
| Senior, Robert M.: Leaf Prints | 12 | 23 |
| Senior, Robert M.: Low-growing Annual Campanulas | 13 | 110 |
| Senior, Robert M.: Low-growing Campanulas of N. America | 12 | 53 |
| Senior, Robert M.: Mimulus nanus | 20 | 182 |
| Senior, Robert M.: Penstemons for the Rock Garden | 18 | 289 |
| Senior, Robert M.: Plant Portraits: Podophyllum emodi | 33 | 258 |
| Senior, Robert M.: Raising Dwarf Evergreens from Cuttings | 33 | 90 |
| Senior, Robert M.: Rocky Mountain National Park | 20 | 122 |
| Senior, Robert M.: Some Acantholimons | 36 | 253 |
| Senior, Robert M.: Some American Campanulas | 15 | 124 |
| Senior, Robert M.: The Flora of Big Bend National Park | 15 | 305 |
| Senior, Robert M.: The Flora of Northern New Mexico | 25 | 127 |
| Senior, Robert M.: The Flora of South Central Idaho | 7 | 200 |
| Senior, Robert M.: Two Interesting Hybrids | 21 | 126 |
| Senior, Robert M.: Waterton Lakes National Park | 25 | 38 |
| Senior, Robert M.: Zion National Park | 23 | 295 |