Rootstock. Same as Rhizome.
Rostrate. Having a beak or spur.
Rosulate. In the form of a rosette.
Rotate (corolla). Wheel-shaped; flat and circular in outline.
Rotund. Rounded in outline.
Rudiment. A very partially developed organ; a vestige.
Rudimentary. But slightly developed.
Rufous. Reddish brown.
Rugose. Wrinkled.
Runcinate. Sharply incised, with the segments directed backward.