Rose Dictionary

Find all important descriptions in our rose dictionary. For more info on diseases search under Rose Care.

A horizon

The uppermost layers of soils consisting of partly decomposed plant remains and relatively fresh leaves and other plant debris; the surface mineral layer, high in organic matter and dark in color; and the lighter colored layer where leaching of solutes and suspended materials occurs.


(adj. abscissile)

The normal shedding of leaves, flowers or fruit from a plant at a special separation layer, or abscission zone.


Auxiliary, subsidiary; as the parts of a flower beyond the necessary male and female organs, such as petals and sepals.

Accessory bud

Accessory Buds which are at or near the nodes but not in the axils of the leaves.

Accessory organs

Parts of a flower that are not directly connected with male and female organs, e.g., petals and sepals, etc.


Stems which lack joints or nodes.


Having no seed leaves, or cotyledons.


Describes leaves with two or more primary or strongly developed secondary veins running in convergent arches towards the apex. Arches not recurved at base.

See also: brochidodromous, eucamptodromous, semicraspedodromous.


Describes flowering seasonal shoots which produce leaves below the inflorescence.

See also: basitonic.


Without leaves.


Apogamy where sexual union is not completed, yet the embryo is produced from the inside layer of the female gametophyte.


Originating from outside a system, such as the leaves of terrestrial plants that fall into a stream. See also: autochthonous.


Describes leaves that are not opposite to each other on the axis, but arranged singly at different heights.


Sexual reproduction; the joining of parental characters.


(alt. ampulla, adj. ampulliform, adj. ampullaceous)

A hollow flasklike organ shaped like a bladder or squat round bottle; e.g., the traps and floats such as those found on the leaves of Nepenthaceae or Utricularia.


Of an inflorescence composed of both staminate and pistillate flowers. 2. With antheridia and archegonia in the same cluster of leaves, i.e., either synoicous or paroicous.


The minute reproductive body, which gives rise to the (often exceedingly obscure) male plantlet in the sexual generation.


Narrow leaves.


Refers to paired leaves which are different in size or shape, common in trailing stemmed gesneriads.


The upper portion of a stamen which contains the pollen sacs.


Sperm, male gamete; one of the minute organs developed in an antheridium.


A fungus that forms grayish/whitish spots on leaves and stems.


Aphids come in almost every colour, from green to yellow, pink, brown, black and especially the purple red colouring of the young leaves and shoots of the rose.

An increased activity of aphids on roses coupled with an excretion of honeydew brings about sooty mould. The sugary sap encourages the growth of the Soot fungus, which blackens the leaves causing reduced photosynthesis. To get rid of the sooty mould one needs to spray insecticide to kill the aphids and simply wash the leaves with a strong jet of water a few times.

It is known that the first aphids were busy on leaves during the carbon age some 270 million years ago. Evolution took place with the appearance of the flowering plants.


Refers to herbal preparations that can stimulate sexual desire.


Without leaves.

Apical Meristem

Non-maturing cells located at the tips of shoots and roots which produce the plant hormone auxin.


Curved gently outward and then downward; generally said of stems, large leaves, and floral clusters.


A nontechnical term that refers to the way things are put together, e.g., an inflorescence may be described by the arrangement of the flowers, or leaves can be arranged opposite or alternate.


Lacking sexual characteristics as in a sterile ray floret; or when referring to reproduction, occurring without the fusion of egg and sperm.


The ‘ear-like’ projection found on the tip of the stipule.


Small lobes at the basal angles of the leaf, usually consisting of cells differing in size, shape, or both from those of the main part of the leaf. Properly used only when there is an outward curve in the outline of the leaf at the base, but often used loosely to denote the basal angles of widely decurrent leaves.


(alt. autocious)

1. Refers to parasites which pass all stages of their life cycle on or within the same host, like certain rust fungus.

2. Having male and female organs on the same plant. See also: heteroecious.


A plant hormone that regulates the bloom cycle for rose buds.


The main line of growth in a plant or organ, e.g., the stem, from which the other parts such as the leaves and flowers grow.


Describes a plant that is prepared for transporting by removing all the soil around its roots.


(alt. basilar)

1. Growing from the base of a stem; used in reference to leaves at the base of the stem. 2. One of the main canes of a rose bush, originating from the bud union. 3. Describes cells at the base or insertion of the leaf, often of different shapes and colors from those of the main part of the leaf.

Black spot

Black spot (alt. blackspot) is one of the most common and important diseases of roses throughout the world.

It is caused by the fungus Diplocarpon rosae. Black spot will cause a general weakening of the plant so that progressively fewer and fewer blooms are formed if the disease is left unchecked due to loss of foliage. Plants so weakened are increasingly subject to winter injury.


An insect larva that tunnels into stems and trunks of shrubs, trees, etc.


1. A more or less modified leaf subtending a flower or belonging to an inflorescence, or sometimes cauline.

2. The similar structure in cryptogams surrounding reproductive organs.


Describes leaves with pinnate venation in which the secondary veins do not terminate at the margins but rather are joined in a series of prominent arches. See also: acrodromous, eucamptodromous, semicraspedodromous.

Bundle scars

iny, somewhat circular dots within the leaf scar, caused by the breaking of the fibrovascular bundles which run through the petioles into the blades of the leaves.


A shrub, especially one that is low and thick with many stems rather than a single trunk.

Capillary water

The part of soil water which is held cohesively as a continuous layer around particles and in spaces, most of it being available to plant roots.


The larvae of butterflies and moths, which often feed on leaves.


Beetles that attack plant roots as larvae and leaves as adults.


(adj. chlorotic)

A yellowing of the leaves, reflecting a deficiency of chlorophyll and caused by waterlogged soil or a lack of nutrients, often iron.


(syn. cirrhate)

Applied to leaves which curl up in drying. Cirrate leaves are more regularly curled than crispate leaves.


The union of parts or organs of the same kind.


Comal tuft, a tuft of leaves at the tip of a stem or branch.


A flask-like structure containing reproductive organs.


(syn. seed leaf)

One of the first leaves to appear after germination (there may be one, two, or more); the foliar portion of the embryo as found in the seed. See also: true leaf.


In roses, the region of the bud union; the point near soil level where the top variety and the understock are joined


Soil-living brownish caterpillars that feed at night, often severing stems of herbaceous plants.


Any of various plant growth hormones, such as kinetin, that grow and promote cell division and delay the senescence of leaves.

Deep Watering

Inundating an area with water for a long period of time, perhaps 24 hours or more, to permeate the deepest layers of subsoil, thereby pulling roots down where they will not easily perish from drought.


A chemical substance which causes a plant to drop its leaves.


(n. defoliation)

1. To cause the leaves of a plant to drop.

2. To remove the leaves of a plant.


Twice grafted. The plant consists of the rootstock, an intermediate scion, and the upper scion

Downy Mildew

Downy mildew refers to any of several types of oomycete microbes that are obligate parasiteof plants. Downy mildews exclusively belong to Peronosporaceae.

Downy Mildew is not as widespread and much more dependent on ideal temperatures and moisture conditions to cause devastating results on roses.

Drip Line

The line that could be drawn on the ground under a tree beneath the outermost tips of the branches. Rain flows off the tree at this point, so it is the area where roots congregate and the best point to place fertilizer, water, etc.

Drip Point

(alt. drip-point, alt. drip-tip)

1. A leaf tip with an extension–acuminate, caudate, aristate–from which water drips during wet conditions.

2. A long drooping tip on leaves, particularly those of rain forest trees.


The stem of a seedling between the cotyledons and the first true leaves.


An organism that grows on leaves. See also: epiphyte.

Facultative Apomict

A plant that can reproduce either sexually or asexually (apomixis.)


An abnormal flattening or coalescence of stems or leaf stalks.


Any partial reversion of the effects of a given process to its source, such as leaves falling to the ground and furnishing calcium for uptake by the roots of the plant.


The reproductive structure of a flowering plant consisting of a pistil and/or stamen, and usually including petals and sepals.


The leaves of a plant taken collectively.

Foliar Diagnosis

Evaluation of the nutrients in a plant, or the plant nutrient requirements of a soil, by analyzing the leaves.

Foliar Feeding

(alt. foliar fertilizing)

The process whereby plants are fertilized by application of liquid onto the leaves rather than through the soil.

Folic Acid

(syn. pteroylglutamic acid)

A member of the B vitamin complex, found mostly in the leaves of plants.


The act or organs of fruiting.


1. The formation of drops of water on plants from moisture in the air.

2. The exudation of liquid water from the uninjured surface of a plant leaf.

3. The process of water being exuded from hydathodes at the enlarged terminations of veins around the margins of the leaves


1. The process of gradually taking plants into a harsher environment, e.g., from the hothouse to the garden.

2. The term can also mean sustaining a plant from summer to winter, which may include a three-staged process:

1) phytochrome clocks signal the shortening days with a color change.

2) Growth ceases, carbohydrates are transported to the roots, and abscisic acid forms at the union of leaf and stem, dropping the leaf and healing the wound. The dropped leaves serve as mulch and protect the roots from excess cold in the winter, while cell walls toughen.

3) A smooth ice forms around the cells without rupturing them, a process called vitrification.


The closed and ripened receptacle of a rose which contains the seed.


Refers to organs or parts that are similar in form or function.


Describes a flower which contains only one set of sexual organs, either stamens or pistils.


Describes a stipule located between the petioles of two opposite leaves.


Refers to the relative placing of organs.

Leaf (pl. leaves)

A usually flat, green structure of a plant where photosynthesis and transpiration take place and attached to a stem or branch.

Leaf Blight

Any of various diseases which lead to the browning and dropping of a plant’s leaves

Leaf Bud

A bud which contains undeveloped leaves.

Leaf Curl

A disease that causes leaves to roll up.

Leaf Litter

The leaves that have fallen from a plant, either through normal seasonal changes or due to disease. Especially in the latter case, leaf litter can harbor pathogens and should be cleaned up promptly, particularly around plants such as roses. In a naturalized, woodland setting, leaf litter can be a normal part of the workings of the garden.

Leaf Miners

Tiny grubs that tunnel in leaves leaving whitish blotches or trails.

Leaf Mold

A form of humus composed of decayed leaves, often used to enrich soil.

Lignification (adj. lignified)

The process by which herbaceous stems become hard and woody.

Meristem (alt. apical meristem)

The undifferentiated tissue from which new cells are formed, e.g., the tips of roots or stems; the growing tip.


A fungus that leaves a thin white coating on the surface where it grows.

Monopodium (pl. monopodia, adj. monopodial)

The main axis of a stem or rhizome maintaining a single direction of growth and giving off lateral branches or stems. See also: sympodium.


With many leaves.


Describes divided leaves, with the lobes held in several to many planes.

Natural Layering

The spontaneous rooting of stems when they make contact with the soil.


The place upon a stem which normally bears a leaf or whorl of leaves.


Describes leaves arranged along a twig or shoot in pairs, opposite each other at a single point along an axis.


Minute leaf-like or much-branched organs among the leaves.

Paraphysis (pl. paraphyses)

1. Jointed hyaline hairs growing among the reproductive organs. 2. The thread-like hyphae between the asci.


Having its male and female organs in the same cluster, but not mixed, the antheridia being in the axils of the perichaetial bracts below the archegonia.


An outer, cortical protective layer of many roots and stems that typically consists of phellem, phellogen, and phelloderm


Lasting beyond maturity without being shed, as some leaves remaining through winter, etc.


A division of the corolla; one of a circle of modified leaves immediately outside the reproductive organs, usually brightly colored.

Petal Cells

The tissues and cells that contribute to scent biosynthesis in scented and nonscented Rosa x hybrida cultivars as part of a detailed cytological analysis of the rose petal were localised. Adaxial petal epidermal cells have a typical conical, papillate shape whereas abaxial petal epidermal cells are flat. Using two different techniques, solid/liquid phase extraction and headspace collection of volatiles, is was shown that, in roses, both epidermal layers are capable of producing and emitting scent volatiles, despite the different morphologies of the cells of these two tissues. Moreover, OOMT, an enzyme involved in scent molecule biosynthesis, was localized in both epidermal layers. These results are discussed in view of results found in others species such as Antirrhinum majus, where it has been shown that the adaxial epidermis is the preferential site of scent production and emission

Phenology (adj. phenological)

The science of the relations between climate and periodic biological phenomena, e.g., the fruiting of plants or the color change of leaves.


Refers to a plant’s adaption to surrounding conditions, which are neither stable nor capable of being inherited (genotypic). Such visible changes occur especially where plants are grown in a wide variety of conditions, but will not carry over to different conditions, e.g., red leaves may occur in hot dry areas, but turn green when grown in normal conditions.


Chemical substances produced by animals that attract and stimulate sexual partners of the same species.

Pinch Back (syn. pinch out)

To remove the growing tips on main stems, usually using the fingernails of thumb and forefinger, in order to induce branching and thereby thicken and strengthen the plant.


1. Consisting of several leaflets arranged on each side of a common petiole or rachis on a compound leaf or frond.

2. The feather vein pattern of simple leaves.


The spongy or hollow center of twig or some stems.


Any of the members of the kingdom Plantae typically lacking locomotive movement or obvious nervous or sensory organs and possessing cellulose cell walls and usually capable of photosynthesis.

Plant Breeders’ Rights

Plant breeders’ rights (PBR), also known as plant variety rights (PVR), are rights granted to the breeder of a new variety of plant that give him exclusive control over the propagating material (including seed, cuttings, divisions, tissue culture) and harvested material (cut flowers, fruit, foliage) of a new variety for a number of years.


The tendency for plants to develop from its poles, roots growing down, stems growing upward, making it essential to plant bulbs, etc, in the correct position.

Powdery Mildew

A fungus forming a white powdery coating on leaves and stems.

Proliferous (syn. proliferating)

1. Freely producing offshoots, bulblets, or plantlets.

2. In mosses, bearing young shoots from the antheridial or archegonial cluster of leaves.


Any structure having the capacity to give rise to a new plant, whether through sexual or asexual (vegetative) reproduction. This includes seeds, spores, and any part of the vegetative body capable of independent growth if detached from the parent.


An erect aerial growth which appears to be a stem with leaves, but is actually packed or overlapping sheaths and stalks of essentially basal leaves


1. A vertical row, as of leaves. When you sight along the length of a branch from the tip end, if it appears there are two rows of leaves, either opposite or alternate, the branch is 2-ranked; if three rows, it is 3-ranked, etc.

2. In taxonomy, the position of a taxon in the hierarchy, e.g., species, genus, family, etc.


1. The more or less expanded or produced portion of an axis which bears the organs of a flower (the torus) or the collected flowers of a head, and in roses, enfolds the developing ovaries to form a hip.

2. Any similar structure in cryptogams

Rejuvenation pruning

The practice of cutting all the main stems of a shrub back to within half-inch of the ground during winter dormancy.

Retentive sepals

Sepals that remain attached to the apex of the receptacle after it has ripened into a hip.

Rootstock (syn. rhizome, syn. understock)

1. A rhizome.

2. The root system and lower portion of a woody plant to which a graft of a more desirable plant is attached.


Leave a Reply