| Edward Palmer |
Algae; Bryophytes; Spermatophytes |
| Charles C. Parry |
Algae; Bryophytes; Spermatophytes |
| George W. Perry |
Algae |
| Nicolas Pike |
Algae; Bryophytes |
| Cyrus G. Pringle |
Algae; Bryophytes; Mycology; Spermatophytes |
| Eugene Abraham Rau |
Bryophytes; Mycology; Algae; Musci; Pteridophytes; Phanerogams; Cryptogams |
| Clyde F. Reed |
Algae; Bryophytes; Pteridophytes; Spermatophytes; Lichens |
| Herbert M. Richards |
Algae |
| Joseph N. Rose |
Algae; Bryophytes; Cactaceae; Ferns; Fungi; Spermatophytes |
| Henry H. Rusby |
Algae; Spermatophytes; Bryophytes; Lichens |
| Per Axel Rydberg |
Algae; Bryophytes; Mycology; Phanerogams; Pteridophytes; Spermatophytes |
| Henry P. Sartwell |
Spermatophytes; Cyperaceae; Bryophytes; Algae; Characeae |
| Albert Schneider |
Algae; Lichens; Mycology |
| Arthur C. V. Schott |
Algae; Bryophytes; Spermatophytes |
| Augustine D. Selby |
Algae; Mycology |
| John A. Shafer |
Algae; Pteridophytes; Spermatophytes; Mycology; Bryophytes |
| Aaron J. Sharp |
Algae; Bryophytes; Mycology; Spermatophytes |
| John Kunkel Small |
Algae; Bryophytes; Pteridophytes; Spermatophytes; Lichens |
| Albert C. Smith |
Algae; Spermatophytes; Pteridophytes; Bryophytes; Lichens |
| Julian A. Steyermark |
Pteridophytes; Spermatophytes; Angiosperms; Bombacaceae; Bryophytes; Algae; Characeae; Lichens |
| William C. Sturgis |
Algae; Cryptogams; Mycology; Bryophytes; Spermatophytes |
| William S. Sullivant |
Bryophytes; Algae; Mosses; Spermatophytes |
| David R. Sumstine |
Algae; Mycology; Spermatophytes |
| Benjamin C. Tharp |
Algae; Mycology; Spermatophytes |
| John Torrey |
Algae; Bryophytes; Euphorbiaceae; Mycology; Pteridophytes; Spermatophytes |