| Jacobinia stellata Robinson & Greenman | Isotype |
| Jacquemontia smithii Robinson & Greenman | Isosyntype |
| Jacquinia pringlei Bartlett | Isotype |
| Jaegeria discoidea Klatt | Isotype |
| Jaliscoa pringlei Watson | Syntype |
| Jatropha costaricensis Webster & Poveda | Unknown |
| Jefea pringlei (Greenm.) J. L. Strother | Unknown |
| Juglans mexicana Watson | Isotype |
| Juncus badium Suksdorf | Isotype |
| Juncus bufonius var. ranarius Farw. | Isotype |
| Juncus mertensianus var. filifolius Suksdorf | Isotype |
| Juncus torreyi forma longipes Farw. | Isotype |
| Jungia pringlei Greenman | Isotype |