Raceme:- A spike-like inflorescence in which the individual flowers are stalked.
Rachis:- The axis of a compound leaf or an inflorescence, the main leaf stalk
Radiate:- Flowerheads in which the outer flowers are larger than the others, or in which the outer petals are significantly larger.
Radicle:- The first root arising from the germinating seed
Ray:- A stalk radiating, out from an umbel - like the spokes of an umbrella.
Ray-floret:- The outer florets of a flowerhead such as a daisy; often elaborated into a distinctive strap-shaped or lobed, partly tubular, structure (ligule). They often surround a central disk of dis­similar florets.
Receptacle:- The part of the stem from which all the floral organs arise.
Recurved:- Turned backwards in a curve.
Reflexed:- Bent abruptly backwards
Reniform:- Kidney-shaped, shaped like a kidney
Repand:- Margins, uneven or wavy, with shallow undulations not as deep as sinuate margins.
Reticulate:- Netted, net-veined, when the smallest veins of a leaf are inter-connected like the meshes of a net.
Reticulate - foveolate:- Covered in a network of minute pits, or depressions.
Reticulate - rugose:- Covered in a network of wrinkles.
Reticulate - veined, when the smallest veins of a leaf are inter-connected like the meshes of a net.
Retrorse - puberulent:- With minute hairs turned backwards or downward
Retrorsely:- Turned backward, turned downward
Retrorsely-aculeolate:- With small prickles or sharp points turned backward, or downwards
Retuse:- Terminating in a round end, the centre of which is depressed.
Revolute:- Rolled downwards - generally applies to leaves in which the margins are turned downwards and inwards.
Rhizome:- An underground or surface stem, often thick and swollen.
Rhomboid, Rhombic:- More or less diamond shaped, nearly square with the petiole at one of the acute angles, with four equal sides.
Rib - ribbed:- longitudinal ridge, with longitudinal ridges.
Rotate:- Wheel-shaped, usually the corolla with a very short tube and spreading lobes.
Rosulate:- Arranged in a rosette.
Ruderal:- Growing in waste places
Rugose:- 1)
wrinkled 2) (more strictly) covered in reticulate lines, with the spaces in between convex.
Rugose - verruclose:- wrinkled with warty, little excrescences or bumps
Rugulose:- Somewhat wrinkled
Ruminate:- Looking as if chewed
Pinnatifid with the lobes pointing towards the base.
Runner:- A fond of aerial stolon which often roots down at the nodes to form a new plant