- secretory cavity
- secretory cell
- secretory hair
- secretory tapetum
- secretory tissue
- section
- seed
- seed coat, testa
- seedling
- segment
- seismonastic movement
- selective absorption
- selective permeability, differential permeability
- selective species
- self-compatibility
- self-pollination
- self-sterility
- semi-ring-porous wood
- semimixis
- seminal root
- seminatural vegetation
- seminiferous scale
- semipermeable membrane
- senecio alkaloid
- senescence
- sensitive plant
- sepal
- separation disc
- septal pore apparatus
- septal pore plug
- septate fiber
- septate fiber tracheid
- septate tracheid
- septate wood fiber
- sere variant
- sere, chronosequence
- series
- sessile leaf
- seta, bristle
- sex hormone
- sex-reversal
- sexine
- sexual cell
- sexual cycle
- sexual generation
- sexual reproduction
- shade density, canopy density
- shade leaf
- shade plant
- shade-enduring plant