- resupinate
- restibilis
- rhizome
- rhodes-grass
- ricinus
- rhizoid
- rhododendron
- ribes
- ringent
- ripicolous
- retuse
- rhamnaceous
- rhizocarp
- rimose
- rimous
- ring
- ring-bark
- rhubarb
- rocambole
- rock-weed
- rocket
- rockfoil
- rootage
- rose-mallow
- rosaceous
- rose-bay
- rotate
- rubiaceous
- rue
- rubiaceae
- rudbeckia
- runner
- rutaceae
- rye
- sabadilla
- runcinate
- sage
- sage-brush
- sago-palm
- saguaro
- sainfoin
- sal
- salal
- rose-apple
- rosemary
- rotundifolious
- roucou
- rowan
- salicaceae
- salix
- salmonberry
- salt-bush
- saltwort
- salvia
- samara
- samphire
- rust
- sabicu
- safflower
- saffron
- sagittaria
- salicornia
- sanguinaria
- sansevieria
- santal
- santol
- santolina
- sap
- sapan-wood
- sapindaceae
- sapodilla
- saprophytic
- sargasso
- sarmentose
- sarmentous
- sarsaparilla
- savory
- scabious
- scallion
- scaly-stalked
- scapose
- sclerogen
- sclerosed
- scolopendrium
- sand-wort
- sanguineous
- santonica
- sapindaceous
- sapota
- sarracenia
- sassafras
- savin
- saxifrage
- scab-wort
- scarious
- scarlet runner
- schizomycete
- scleroma
- sclerosis
- scorzonera