| Name | Horkelia californica subsp. frondosa (Greene) Ertter |
| Authorship | (Greene) Ertter |
| Rank | Subspecies |
| Placed in | Horkelia californica Chamisso & Schlechtendal |
| Holdings | 5 Specimens held in the Harvard University Herbaria identified as Horkelia californica subsp. frondosa (Greene) Ertter |
| Identification made in | [no date] (5) |