Rhombic, in the shape of a rhomb. Rhomboidal, approaching that shape.
Rib, the principal piece, or one of the principal pieces of the framework of a leaf, or any similar elevated line along a body, [49], [50].
Rimose, having chinks or cracks.
Ring, an elastic band on the spore-cases of Ferns, [159].
Ringent, grinning; gaping open, [92].
Riparious, on river-banks.
Rivalis, Latin for growing along brooks; or Rivularis, in rivulets.
Root, [33].
Root-hairs, [35].
Rootlets, small roots, or root-branches, [33].