Science magazines
- Schiedea Spergulina Var. Spergulina
- Schiedea Verticillata
- Schoepfia Arenaria
- Schweinitz's Sunflower
- Scioto Madtom
- Scrub Blazing Star
- Scrub Buckwheat
- Scrub Lupine
- Scrub Mint
- Scrub Plum
- Seabeach Amaranth
- Sebastopol Meadowfoam
- Sensitive Joint-vetch
- Sentry Milk-vetch
- Shale Barren Rock-cress
- Shasta Crayfish
- Shenandoah Salamander
- Shiny Pigtoe Pearlymussel
- Shinyrayed Pocketbook
- Short's Goldenrod