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Glossary: R

raceme raceme
A long array of flowers (inflorescence) with individual stalks (pedicels) for the flowers, each stalk attached directly to the main axis (rachis) of the inflorescence. Flowering starts at the bottom and progresses to the apex.
rachilla rachilla
The main axis of the spikelet in grasses (Poaceae), which bears the spikes.
rachis rachis
The central axis of a leaf, such as that bears the pinnae in ferns.
rame rame
A long inflorescence containing both sessile and stalked flowers (as in Poaceae).
ramentum ramentum
The scales on a plant (usually used with a fern rachis).
rank rank
A vertical row on an axis.
rare
A species with low population levels, at risk of becoming threatened.
ray flower ray flower
Flower with a single, long strap-like "ray" petal that forms the outer ring of a composite head (i.e., the "petals" of a daisy).
receptacle receptacle
The base of a flower, comprised of the enlarged top of the stalk, which holds some or all of the flower parts. In the Asteraceae (aster family), the receptacle is formed from the enlarged top of the peduncle that holds many small flowers (florets).
recurved recurved
Bent or curved downward.
reduced reduced
Lower or smaller than normal.
reflexed reflexed
Abruptly bent backward or downward.
remote remote
Separated from others of same form (as in a flower produced at a distance from other flowers on the same stem).
reniform reniform
Kidney-shaped.
replum replum
Placenta that forms the partition between separating valves of a silique (in Brassicaceae).
resupinate resupinate
With flowers that appear upside-down.
reticulate reticulate
Net-veined or with ribs that inter-connect to form a honeycomb pattern.
retrorse retrorse
Pointing downward or inward toward the basal end.
retuse retuse
With a terminal notch in an otherwise blunt or rounded apex.
revolute revolute
Rolled under, toward the abaxial surface.
rhizomatous rhizomatous
Proliferating by means of underground, horizontal stems (rhizomes).
rhizome rhizome
Underground, horizontal stem.
rhombic rhombic
Diamond-shaped.
root root
The underground part of a plant that anchors the plant to the ground and absorbs nutrients and water.
rosette rosette
A circle of tightly packed leaves, usually at ground level.
rostellum rostellum
A slender projection like a bird beak; on orchids, an outgrowth of the column that keeps the stigma lobe separate from the anthers to avoid self-pollination.
rotate rotate
A corolla that is platter-shaped, without a basal tube.
rounded rounded
With a gently curving outline.
rudimentary
Small and arrested early in development.
rugose rugose
Rough or wrinkled.
rugulate rugulate
Covered with low, mounded ridges or wrinkles, not forming a honeycomb pattern; usually refers to the texture of a quillwort (Isoetes) megasphore.
runner runner
The ultimate branch of a stolon or rhizome.