- Saccate
- Sagittate
- Scaberulous
- Scabrid
- Scale
- Scalpelliform
- Scandent
- Scarious
- Scutellum
- Secondary axis
- Secondary nerves
- Sectile
- Section
- Secund
- Seed
- Semiterete
- Sepal
- Sepals
- Septate
- Septum
- Sericeous
- Serrate
- Serrulate
- Sessile
- Setose
- Sigmoid
- Simple
- Sinuate
- Smooth
- Spatha
- Spatulate
- Spike
- Spur
- Spurred
- Squamulose
- Stamen
- Stelidia
- Stellate
- Sterile bracts
- Stigma
- Stipulaceous
- Strigose
- Style
- Sub-
- Subterete
- Subtribe
- Subulate
- Succulent
- Sulcate
- Superposed
- Suture
- Synsepalum
- Syntype