Common names: R
- rabbit-ear iris
- radiator plant
- ragged robin
- ragweed
- rain lily
- rain tree
- rainbow pink
- rainbow rock cress
- ram's horn
- rambler
- rambling senna
- rambutan
- rampion bellflower
- Rangoon creeper
- Rangpur lime
- rape
- raspberry
- Ratisbon broom
- rattail crassula
- rattan palm
- rattle
- rattlesnake master
- rayed tansy
- red alder
- red amaranth
- red angel's trumpet
- red avens
- red baneberry
- red beard tongue
- red beet
- red bistort
- red buckeye
- red cabbage
- red campion
- red cestrum
- red chokeberry
- red clover
- red currant
- red date
- red dead nettle
- red dock
- red fescue
- red flag bush
- red flax
- red flowered schisandra
- red flowering gum
- red garden orache
- red ginger
- red gum
- red hawthorn
- red helleborine
- red horned poppy
- red horse chestnut
- red hot poker
- red kiwi
- red lady's slipper orchid
- red lantern banksia
- red Latan palm
- red lily
- red lungwort
- red maple
- red morning glory
- red osier dogwood
- red pasque flower
- red passion flower
- red poppy
- red raspberry
- red ribbons
- red river gum
- red sage
- red silky oak
- red snakebark maple
- red valerian
- red vine spinach
- red-barked gogwood
- red-berried elder
- red-veined dock
- redbud
- redflower currant
- redleaf rose
- redvein maple
- redwhisker clammyweed
- redwood
- reed canarygrass
- reed grass
- reflexed stonecrop
- regal lily
- Rembrandt tulip
- remontant rose
- remote sedge
- resin spurge
- restharrow
- rhapontic rhubarb
- rhododendron
- rhubarb
- ribbon pincushion
- rice
- rice paper tree
- river birch
- river bottlebrush
- riverbank vine
- Robin's plantain
- rock cherry
- rock cinquefoil
- rock cress
- rock jasmine
- rock madwort
- rock purslane
- rock rose
- rock soapwort
- rock thyme
- rock valerian
- rockcress
- rocket candytuft
- rocket larkspur
- rockrose
- rockweed
- rocky daisy
- Rocky Mountain alpine fleabane
- Rocky Mountain phlox
- Rocky Mountains columbine
- Rocky Mountains goldenrod
- Roger's firethorn
- Romaine lettuce
- Roman calamint
- Roman chamomile
- rose
- rose cactus
- rose campion
- rose coneflower
- rose heath
- rose of China
- rose of Sharon
- rose pelargonium
- rose root
- rose vervain
- rose-gold pussy willow
- rosebay willow herb
- roseleaf sage
- roselle
- rosemallow
- rosemary
- rosemary grevillea
- roseroot
- rosewood
- rough blazing star
- rough goldenrod
- rough horsetail
- rough-leaved hydrangea
- round-headed leek
- round-headed rampion
- round-leaf rhododendron
- round-leaved birthwort
- round-leaved mint bush
- round-leaved saxifrage
- round-leaved sundew
- round-leaved tea tree
- rowan
- royal azalea
- royal catchfly
- royal fern
- royal Jacob's ladder
- royal palm
- rubber tree
- ruby grass
- rum cherry
- runner bean
- rush
- Russian arborvitae
- Russian belladonna
- Russian hollyhock
- Russian olive
- Russian sage
- Russian vine
- rusty fig
- rusty foxglove
- rusty leaved alpen rose
- rutabaga
- rye