| Title | Copies | Duplicated Elsewhere? |
| Art Forms from Plant Life | 2 -- both inscribed | No -- bound book is unique |
| Contributions to Chemistry of the Plant Cell Wall | Yes -- Harlow's files | |
| Fruit Key and Twig Key to Trees and Shrubs | 1 | No |
| Fruit Key to Northeastern Trees | 1 | No |
| Inside Wood | 3 -- 2 inscribed (to library & archives) | Yes -- correction copy |
| New Leica Manual | 1 -- inscribed TO Harlow | No |
| Patterns of Life | 1 | No |
| Poison Ivy and Poison Sumac | 3 | No -- this edition is unique |
| Textbook of Dendrology | 4 -- none Harlow's | Yes -- correction copies |
| The Effect of Site on the Structure and Growth of White Cedar Thuya occidentalis L | 2 | No |
| Trees of the Eastern United States and Canada | 2 -- both inscribed | Yes -- correction copies |
| Ways of the Woods | 1 | No -- bound book is unique |