glossary

Glossary of Gardening Terms

Index R

Raceme:		A type of inflorescence on which individual flowers are attached by non-branched pedicels.
Rachis:		Main axis of a compound leaf or inflorescence.
Radial:		Spine at the perimeter of an areole on a cactus.
Radical:		Refers to basal leaves that grow from or near ground level.
Rank:		Refers to a linear arrangement of leaves.
Ray floret:		The small strap-shaped florets found around the perimeter of a capitulum, and resembling petals.
Receptacle:		The part of the stem to which flowers are attached to form an inflorescence.
Recurved:		Arched backwards.
Reflexed:		Arched or bent sharply back upon itself.
Relative humidity:		The measurement of the amount of moisture in the atmosphere.
Remontant:		Refers to a plant that flowers more than once within a growing season.
Renewal pruning:		(see renovation pruning)
Reniform:		Kidney-shaped.
Renovation pruning:		Hard pruning to rejuvenate an old or overgrown shrub.
Repot:		To remove a plant from an outgrown pot and re-establish it in a larger container. ( Or repot in the same size pot but with fresh compost).
Reproduction:		Process of producing new individuals by either sexual or asexual (vegetative) methods.
Respiration:		The breakdown of food substances within the cell to release energy to power cellular functions.
Resting period:		(see dormancy)
Restrictive Pruning:		Annual pruning to limit growth.
Reversion:		Genetic change within a sport or chimaera in which a plant or part of a plant reverts to it's original character.
Rhizobium:		A genus of bacteria which inhabit the roots of legumes and fix atmospheric nitrogen.
Rhizome:		An underground stem which can be distinguished from roots by the presence of nodes and internodes.
Rib:		Ridge , normally vertical, formed on the stem of a cactus. Refers to the primary vein on a leaf
Ripening:		Maturing of fruit. Maturing of young shoots (wood) on trees and shrubs, or of bulbs.
Ripewood cutting:		Cutting of a mature shoot taken from an evergreen plant, from late summer to early winter.
Rock-dwelling:		Lithophytic.
Rock Garden:		Environment created in garden suitable for growing Alpines and similar plants.
Rock plant:		Any small plant grow in association with Alpines, and with similar cultivation requirements.
Root:		Part of plant normally below ground, serving as a mechanical support and to convey nutrients from the soil. To insert cuttings in a compost where they will produce roots.
Root Ball:		Mass of roots and soil or compost attached to them, formed by a plant in a container or in the ground.
Root cap:		The group of cells covering the tip of an expanding root, protecting the root's meristematic region from abrasion.
Root cutting:		Cutting taken from vigorous, young shoots during winter.
Root Stock:		Underground part of a plant. The crown and root system of any herbaceous perennial, from which new plants arise. Plant upon which a scion is grafted.
Root pruning:		Cutting large unbranched roots to encourage development of a more fibrous root system near the plant which will lead to higher success with transplanting.
Root crop:		Any vegetable grown primarily for consumption of the true root. Not all underground plant parts are true roots.
Rooting hormone:		A powder or liquid growth hormone, used to promote the development of roots on a cutting.
Root hair:		A projection from an epidermal cell near the actively growing tip of a root. Root hairs serve to expand the surface area of the root permitting increased water absorption.
Rootstock:		The bottom portion of a grafted plant to which the scion is attached.
Rosette:		A growth form characterised by a very short stem and leaves radiating outward from a central point (e.g., Dandelions).
Rounded:		Roughly or fully circular in outline.
Runner:		Creeping stem arising from main plant and taking root at the nodes, thus producing new plants vegetatively; a procumbent stolon. (Above ground, as in strawberries, or, below ground, as in couch grass.)
Rust:		A small parasitic fungi.