Radicle
Ramiform pit
Raphe
Raphide
Ray, heterocellular
Ray, homocellular
Ray initial
Ray, multiseriate
Ray, pith
Ray tracheid
Ray, uniseriate
Ray, vascular
Reaction wood
Resin duct or canal
Reticulate cell wall thickening
Reticulate venation
Rhexigenous
Rhizodermis (see epidermis)
Rhytidome
Ribosome
Ring-porous wood
Root cap
Root, contractile
Root hair