Rough Barnyardgrass          

Rough Bluegrass      

Rough Bugleweed      

Rough Cocklebur          

Rough Coneflower          

Rough Dropseed          

Rough False Pennyroyal          

Rough Pricklypoppy          

Rough Rattlesnakeroot          

Roughfruit Amaranth          

Roughfruit Scaleseed          

Roughleaf Dogwood      

Roundfruit Hedgehyssop          

Roundhead Lespedeza      

Roundhead Prairie Clover          

Roundhead Rush      

Roundleaf Bladderpod          

Roundleaf Geranium          

Roundleaf Greenbrier      

Roundleaf Monkeyflower          

Roundleaf Mudplantain          

Roundleaf Ragwort          

Roundseed Panicgrass          

Roundseed St. Johnswort          

Roundstem False Foxglove          

Royal Catchfly          

Royal Fern      

Rubber Rabbitbrush          

Rubberweed          

Rue Anemone          

Rufous Bulrush      

Running Buffalo Clover          

Running Fleabane          

Rush          

Rush Skeletonplant          

Rushpea          

Russian Leafy Spurge          

Russian Olive      

Russian Thistle          

Rusty Blackhaw          

Rusty Lupine          

Rye          

Rye Brome          

Ryegrass