Rafinesquia californica
Raillardella argentea
Raillardella scaposa
Ranunculus alismifolius var alismellis
Ranunculus aquatilis var. diffusus
Ranunculus californicus var. californicus
Ranunculus eschscholtzii
Ranunculus eschscholtzii var. oxynotis
Ranunculus ficaria
Ranunculus hystriculus
Ranunculus japonicus
Ranunculus montanus
Ranunculus occidentalis
Ranunculus occidentalis var. occidentalis
Ranunculus orthorhynchus var. orthorhynchus
Ranunculus sp.
Raphanus raphanistrum
Raphiolepis indica
Reseda lutea
Retanilla ephedra
Rhamnus ilicifolia
Rhinanthus serotinus
Rhinotropus cornuta var. cornuta
Rhodiola integrifolia ssp. integrifolia
Rhododendron albrechtii
Rhododendron arboreum subsection arborea
Rhododendron arboreum ssp. delavayi
Rhododendron augustinii subsection triflora
Rhododendron austrinum subsection pentanthera
Rhododendron brookeanum ssp. kinabaluense subsection vireya
Rhododendron burmanicum
Rhododendron canescens subsection pentanthera
Rhododendron celebicum subsection vireya
Rhododendron columbianum
Rhododendron decorum subsection fortunea
Rhododendron dendricola subsection maddenia
Rhododendron fortunei subsection fortunea
Rhododendron grande subsection grandia
Rhododendron irroratum subsection irrorata
Rhododendron irroratum ssp. yiliangense subsection irrorata
Rhododendron johnstoneanum subsection maddenia
Rhododendron kanehirae section tsutsusi
Rhododendron keiskei var. ozawae subsection triflora
Rhododendron latoucheae
Rhododendron macrophyllum
Rhododendron molle ssp. japonicum subsection sinensia
Rhododendron moulmainense (or Rhododendron montroseanum)
Rhododendron neriflorum ssp. neriflorum subsection neriflorum
Rhododendron occidentale
Rhododendron ovatum subsection azaleastrum
Rhododendron prinophyllum subsection pentanthera
Rhododendron racemosum subsection scabrifolia
Rhododendron simsii section tsutsusi
Rhododendron spinuliferum subsection scabrifolia
Rhododendron veitchianum subsection maddenia
Rhus aromatica
Rhus integrifolia
Rhus ovata
Ribes cereum var. cereum
Ribes montigenum
Ribes nevadense
Ribes roezlii
Ribes sanguineum
Ribes sanguineum var. glutinosum
Ribes uva-crispa
Ribes viscosissimum
Ribes sp.
Roldana aschenborniana
Roldana lobata
Romneya coulteri
Romneya trichocalyx
Rosa bridgesii
Rosa canina
Rosa rugosa
Rosa sericea
Rosa setigera
Rosa woodsii ssp. gratissima
Rosa sp.
Rotala rotundifolia
Rubus armeniacus
Rubus glaucifolius
Rubus parviflorus
Rubus ursinus
Rudbeckia californica var. californica
Rudbeckia laciniata
Rudbeckia triloba
Rudbeckia sp.
Rumex acetosella
Rumex conglomeratus
Rumex crispus?
Rumex paucifolius
Ruscus hypophyllum