The following Glossary has been provided by Alberta Agriculture and Forestry from the Alberta Forage Manual – 2nd edition. Additions to the Glossary have been provided by Forage Agrologists.



An acid quality or state. Solutions with pH below 7.0 show acidity. Acid is the opposite of alkaline or basic. An acid compound yields hydrogen ions when dissolved in water.

Acid Detergent Fiber (ADF)

The highly indigestible portion of the forage (lignin, cellulose, silica) is called acid detergent fiber. ADF is generally used to calculate digestibility and energy. Forages with a high ADF level have a lower digestibility and lower energy than forages that have low levels of ADF.

Adventitious Roots

Roots originating from the nodes at the base of the tillers and the nodes of rhizomes and stolons, which become the dominant root system for the grass. Grasses have mainly adventitious roots.


Residual or regrowth of forage produced after haying or grazing. Aftermath growth is sometimes grazed in the fall, after plants have become dormant.


An alkaline soil is one with a pH above 7.0, the opposite of acidic.


Alkaloids are amines or organic compounds produced naturally by some forage species. Alkaloids can cause poor palatability and potential toxicity of some grasses for livestock. Some grasses such as reed canarygrass have varieties with high levels of alkaloids. Newer varieties of reed canarygrass have low levels of alkaloids.


Allelopathy is the harmful effects of one plant on another plant by the release of chemicals from plant parts through leaching, root exudation, volatilization, residue decomposition, etc. These actions are a process a plant uses to keep other plants from growing too close to it.

Animal Units (AU)

An animal unit is based on forage consumption by a 454 kg (1,000 lb) cow with or without a calf. An animal unit month (AUM) consumes approximately 380 kg/month (840 lb/month) of forage based on a daily consumption of 13 kg/day (28 lb/day).

Animal Unit Equivalent (AUE)

The animal unit is adjusted for other animals by adjusting for animal type, class or size and is given animal unit equivalents (AUE). This figure adjusts for animal weight and intake. A 454 kg (1,000 lb) cow with or without a calf is one animal unit and a yearling heifer 300 kg (700 lb) has an animal unit equivalent of 0.67.


Plants that germinate, establish, flower, set seed and die in one growing season.


In forage, the term means having a negative effect on daily intake, productivity or health of livestock.


An appendage located at the base of the grass leaf blade where the blade is attached to the sheath. Auricles are generally paired, arising from opposite margins of the leaf, may be rudimentary or claw-like and may wrap around the stem until the pairs overlap.


Autotoxicity is a type of allelopathy where a species, through the production of chemicals that escape or are released into the soil, directly inhibits the growth of that same species. Alfalfa autotoxicity is the process in which established alfalfa plants produce a chemical or chemicals that escape into the soil. This chemical prevents the establishment or reduces the growth of new alfalfa plants if seeded too soon following an old stand or if trying to no-till new alfalfa seed into an established alfalfa field.


A slender bristle, usually found projecting from the back or tip of a lemma (outer seed coat) or glume. Awns can be short or long and are sometimes called beards.


The upper angle between a branch or leaf where it is attached to the stem.



The part of an organ, such as a leaf, nearest its point of attachment. At the base, for example, basal leaves are produced from the base of the plant, at or near ground level.


Solution with pH above 7.0, the opposite of acidic. Basic is the same as alkaline. Basic compounds react with acids to produce salts.


A plant that completes its life cycle in two years. A true biennial is a plant that germinates, establishes and produces only vegetation in its first year and then produces vegetation and seed and dies in its second year. Sweet clover is a biennial.


The expanded, wide, usually flat part of a leaf. In grasses, the blade extends from the sheath and away from the stem.


Excessive accumulation of gases in the rumen.

Boot Stage

The stage in grasses when the head is enclosed by the sheath of the top leaf, also called the flag leaf stage. The flag leaf is the last leaf produced by the tiller.


An unexpanded leaf, shoot, branch or flower.


Grasses that produce no rhizomes or stolons, tufted.



The above-ground portion of a plant stand. It may be expressed as percentage of ground cover.


Compounds, such as sugars, starch and other soluble carbohydrates (nonstructural) and cellulose and hemicellulose (structural), that are made of carbon, hydrogen and oxygen, usually in the ratio of 1:2:1 (CH2O).


A carbohydrate formed from glucose that is the major constituent of the plant cell walls.

Carrying Capacity

The maximum total stocking rate that can be achieved over a specified length of time (for example AU/ha for the grazing season). The sum of all grazing days and stocking rates will determine the maximum carrying capacity of the pasture, which maintains a target level of production without affecting the ecosystem.


In grasses, the collar is located on the outside of the leaf, where the blade attaches to the sheath.

Companion Crop

A companion crop is a cover crop (usually a cereal crop) grown with a perennial forage during the establishment year, but may also include annual or short-lived forage species in mixtures. Companion crops are competitive with forage seedlings.

Compound Leaf

A leaf that is divided into two or more parts (leaflets).

Continuous Grazing

A grazing practice where grazing is on one pasture and the livestock have unrestricted access for long grazing periods.

Cool-season Plants

Plant species that grow best in cool temperatures (15 – 25ºC). In photosynthesis, they first produce a 3 carbon acid (3 – phosphoglyceric acid) to make carbohydrates. This C3 photosynthesis occurs at cooler temperatures than C4 photosynthesis, but is less efficient at warmer temperatures. All perennial forages used in Alberta are cool-season species.


Coumarin changes to dicoumarol, an anticoagulant, when the hay from forage species containing coumarin becomes moldy. Anticoagulants prevent blood from clotting. Coumarin was once commonly found in sweet clover, but newer varieties are coumarin-free.

Cover Crop

See Companion crop.

Creeping Root

An underground stem, a rhizome.


Transfer the pollen from the flower of one plant to the flower of another plant of the same species.


The portion of a plant where the stem and the root meet and where tiller buds and rhizomes are first formed. The crown of perennial forages overwinters to produce new tillers and additional rhizomes in the spring.

Crude Fibre

This is the fibrous part of the plant that has very little nutritional value and is not very digestible. Cellulose is an example of the fibre in the plant. The terms acid detergent fiber (ADF) and neutral detergent fiber (NDF) are generally used instead of crude fiber.

Crude Protein

Proteins are made up of amino acids. Protein is determined by measuring the nitrogen in the forages and multiplying by 6.25. Plant proteins are used by the animal to produce animal proteins (e.g. meat and milk).


A population of a plant species that has been bred and selected for specific characteristics such as winter hardiness or disease resistance; in the crop sciences, a cultivar is a cultivated variety (also known as variety).


Decreaser Species

Decreaser species are well liked by livestock and are the first forage species in excellent condition rangeland to decrease in abundance if grazing is too heavy.


Plant structures that have a determinate, limited growth period and do not continue growth indefinitely. They grow for a limited time until they reach a certain size or level of maturity and then stop growing, such as the growth form where the terminal growing point develops a flower and terminates the vegetative growth of the shoot, e.g. red clover has determinate shoots.


Refers to the proportion of the forage digested by the animal. The digestibility is generally expressed as a percentage. Digestibility may be expressed as digestible dry matter (DDM), which is the forage dry weight minus the feces dry weight. In vitro digestibilities are determined in a laboratory using rumen microflora in a test tube.


A plant with two sets of chromosomes in its cells.


This is where terminal buds of a plant or shoot inhibit the development of lateral buds.

Dry Matter

Feeds are heated in an oven to eliminate the moisture in a sample to determine the moisture-free weight of the sample. This process enables samples to be compared more accurately on an equal 100 per cent moisture-free basis.


DeciSiemens per meter is a measure of electrical conductivity of a solution and is used to determine the salinity of soil.



A living organism that lives all or part of its life cycle inside its host plant in a parasitic or symbiotic relationship.




The wearing away of soil or the movement of soil from one location to another by natural forces such as wind or water.


Fibrous Roots

Very fine, thread-like roots. Grasses have fibrous roots.


In grasses, the floret is the flower that develops to be the seed, lemma and palea.


A forage crop is one grown for pasture, hay or silage. The vegetative plant material, including stems, leaves and heads, used for livestock feed. Grasses are often developed for suitability for forage (i.e. forage types) versus turf or reclamation types, etc.


Germination (percent)

What percent of the seed in a lot will germinate under appropriate conditions.


A slightly waxy often bluish or whitish coating on plants that can be rubbed off.


A bract (scale-like leaf) attached near the base of a grass spikelet. Glumes may be broad or narrow and may have an awn.


Plants that are members of the Poaceae plant family. Grasses are monocotyledons with parallel leaf veins. Stems are usually round but may be somewhat flattened and usually hollow, except at the nodes.


Hard Seed

Seed with a seed coat that is impervious to water and will not germinate, even though it is viable. Legumes commonly produce seed with a high portion of hard seed. Hard seed will de-harden in the soil over time, due to freezing and thawing, etc. Hard seed can also be scarified (etched or scratched) by mechanical or other means to enable it to take up water more quickly and germinate.


Grasses are heading from the time the head begins to emerge from the boot until it is fully out of the boot. The stem continues to grow and elongate, elevating the head, even after heading is complete.


Increaser Species

Increaser rangeland plant species tend to increase in abundance and take the place of the decreaser species under continued heavy grazing pressure. The increasers will also begin to decrease when heavy and close grazing continues on an on-going basis.


Indeterminate growth is growth that is not terminated once a genetically pre-determined structure has completely formed as it does when the growth is determinate. A plant that grows and produces flowers until killed by frost or some other external factor is called indeterminate. These plants have flowers on lateral branches, enabling the stem to continue vegetative growth. Indeterminate plants flower over an extended period. Examples include alfalfa and alsike clover.


The flowering structure of a plant or the arrangement of the flowers of a plant. The inflorescence can be a head, raceme, spike, panicle, etc.


The application of nitrogen-fixing rhizobia bacteria to the seed of legumes. These bacteria are forage species specific or may be appropriate for a group of forage legumes. For example, the same rhizobia species can be used for alsike, red and white clover.


The portion of a stem between the nodes. Internodes lengthen as grass stems grow and elongate.

Introduced Forage

A species that is not naturally present in the vegetation of an area but that is brought in from another country or region, e.g. alfalfa.

Invader Species

Plants that are absent from climax rangeland, but will invade under disturbance or continued overuse.

IVDMD – In Vitro Dry Matter Disappearance

A method of estimating the dry matter lost following the incubation of the forage in rumen micro flora in the laboratory. IVDMD is expressed as a percentage of the initial sample and is a measurement of the digestibility of the forage.

IVDOM – In Vitro Digestible Organic Matter

In vitro digestibilities are determined in a laboratory using rumen microflora in a test tube. IVDOM refers to the proportion of the forage organic matter digested by the animal. It is generally expressed as a percentage and is used as a measure of digestibility.


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Killing Frost

When air temperature drops below -4oC for a period sufficient to cause significant damage to plant cells.


Lateral Root

A branch off the primary root. It is often small, but may be as large as the primary root.

Leaf Axil

The junction where a leaf attaches to a stem. See “axil.”

Leaf Blade

The expanded portion of a leaf. See “blade.”


A division of a compound leaf. For example, white clover leaves have three leaflets.

Leaf Margins

The edges of a leaf.

Leaf Sheath

In grasses, the lower portion of the leaf that surrounds the stem. It is below the blade. Grass sheaths may have open, closed or overlapping margins.


A plant in the Fabaceae family. This family is made up of broadleaf forbs that have a symbiotic relationship with rhizobia bacteria, which fix atmospheric nitrogen. Alfalfa, clovers, etc. are examples of legumes.


Together with the palea, the lemma encloses the grass flower or seed. Relative to the palea, the lemma is usually longer and attached lower to the outside of and with its edges overlapping the palea. The lemma may have an awn. Most grass seeds have the lemma and palea attached after threshing, e.g. bromegrass, fescue, wheatgrasses. The lemma and palea are sometimes called hulls.


In grasses, membranous tissue located between the stem and the leaf blade, near where the blade attaches to the sheath.


A medium textured soil composed of a desirable portion of sand, silt and clay.


Lodging is the breaking or bending of stems near the base so that the plants lie on the ground, often due to weak stems. Plant height, wall thickness and cell wall lignification can affect lodging. Tall plants have a higher tendency to lodge than short plants. Adverse weather conditions such as winds and heavy rains can cause lodging as well.



The central vein of a leaf.


Having several leaflets. Normal alfalfas have three leaflets, whereas multifoliates can have up to eleven leaflets. Multifoliate alfalfas in Alberta generally only have five leaflets.


Native Plant

A plant that is indigenous to or originating from an area, the opposite of introduced, e.g. Western wheatgrass is native to Alberta.


Introduced plants that are well adapted to a region and have become established in the local ecosystem over time. Examples of naturalized plants in Alberta include white clover and Kentucky bluegrass.

Neutral Detergent Fiber (NDF)

The indigestible and slowly digestible components (cellulose, hemicellulose, lignin and ash) in the cell walls of the plant are called neutral detergent fibers (NDF). This is a more complete measure of fiber in the forage than acid detergent fiber (ADF), and the NDF levels are always higher than ADF. NDF is a good indicator of the potential intake of forage; as NDF increases, intake decreases.

Nitrogen Fixation

The symbiotic relationship between rhizobia bacteria and a legume where the bacteria form a nodule on a root or root hair and convert atmospheric nitrogen available in the air between the soil particles into a nitrogen form that is usable by the plant.


The point from which growth occurs on a stem and a point from which leaves develop and are attached. On grass stems, a node appears as a swelling, which is solid on the inside.


In legumes, a small growth on a root where rhizobia bacteria fix atmospheric nitrogen and convert it to ammonia, which plants can use.


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A smaller, fenced pasture, a subdivision or one of many subdivisions of a larger grazing area. Paddocks enable better control of the grazing of the pasture.


The acceptability of a plant to the livestock grazing or consuming it. Given a choice, livestock will find one forage species or parts of the same forage more palatable than another.


Divided or lobed. On palmate legume leaves, the leaflets arise from a common point, without a stalk. Examples include the leaves of alsike, kura, red and white clover.


A multi-branched cluster of flowers, each with its own stalk. A panicle has a subdivision in addition to that of a raceme. The lower branches have longer stalks and open first. Bromegrass, fescue, bluegrass and oats have panicles.


Pathogens are infectious agents that can cause a disease or illness to its host.

Perennial Plant

A plant that persists for more than two years. For legumes and grasses commonly used for forage, the shoots are annual and regrow from the perennial crown in spring.


Solutions may be acidic (below pH 7.0), neutral (pH = 7.0) or basic (pH above 7.0). Basic is the same as alkaline. The pH scale is logarithmic, e.g. a solution with an acidity of 5.0 is ten times more acidic than one with a pH of 6.0.


An abnormal reaction or sensitization of the skin of an animal to sunlight due to a compound present in forage that has been eaten by the animal.


The process by which green plants use the energy from sunlight to produce carbohydrates from carbon dioxide and water.


A leaf arrangement on a compound leaf where the leaflets are on each side of a common axis. An odd pinnate leaf has a single leaflet at the tip, giving it an odd number of leaflets. On legumes with three leaflets, if the terminal leaflet has a stalk, it is a pinnate leaf arrangement. Alfalfa, sweet clover and cicer milkvetch have odd pinnate leaf arrangements.


The fruiting body of legumes. The pod is the shell that contains the seed or seeds.


An insect that transfers pollen from the male anthers of a flower to the female stigma of a flower to accomplish fertilization of the flower for seed production. Insects are the most important pollinators of legumes. Grasses are commonly wind pollinated.


Parts per billion.


To lie flat on the ground.


Covered with hair.

Pure Live Seed (PLS)

The percentage of viable seed within a seed lot; calculated by multiplying the percent germination by the percent purity of the see lot. Using a Pure Live Seed calculation allows for forages to be seeded at proper rates to obtain a productive stand.


The percentage of the desired species in relation to the total quantity, including other species, weed seed, and foreign matter.


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A flower structure with each flower borne on a short stalk attached to a central stalk. The flower structure of alfalfa is a raceme.


The process of returning land to its natural or near natural state or form; often involves seeding suitable native plant species.


The new forage growth following a harvest of the initial top growth


In this manual, re-seeding refers to plants setting seed, which can then shatter onto the ground and germinate to establish new seedlings.


Period of time during the growing season when plants are left ungrazed or unharvested.


A horizontal, underground stem, sometimes called a creeping root or rootstock. It can produce shoots and adventitious roots at the nodes and enable the plant to spread.

Riparian Area

The “moist green zone” found between the dry upland and the water in waterbodies (seasonal or permanent). This transition zone is important habitat for many plant, mammal, bird, and insect species.


A dense cluster of leaves on a very short, basal stem.

Rotational Grazing

A grazing practice where livestock graze a pasture for a short period of time followed by a period of rest that allows plants to recover and regrow. Two or more paddocks are used in a rotation.



A measure of salt concentration. See “dS/m.”


A saturated soil contains the maximum amount of moisture that it can hold.


Rough to the touch.


To etch or scratch the hard seed coat of a seed (e.g. a cicer milkvetch seed) so that it will absorb water, enabling it to germinate. The process usually involves mechanical abrasion, but may be done chemically.

Seed Bank

Un-germinated seeds present in the soil, generally from forage crops that have produced seed that has shattered onto the ground.

Seed Cover

Grasses have a lemma (outer seed cover) and palea (inner seed cover), which protect the seeds. They are sometimes called hulls.


Fertilization of the ovary of a plant with the pollen of the same plant.


A climate where evaporation exceeds precipitation.


The natural aging process of plant tissues and the ultimate deterioration of the plant tissue functions, i.e. as a leaf matures, it senesces and dries up.


Having sharp teeth pointing forward.


In grasses, the sheath is the tubular, lower portion of the leaf that arises from a node and surrounds the stem. Opposing sheath margins may be separated (open), grown together (closed) or overlapping.


See “tiller.”

Simulated Grazing

To use machine harvesting to estimate the potential of pasture production, usually involving multiple cuttings per season.


Surface soil permeated by and held together by forage roots and/or rhizomes.

Sod Bound

Grass sod that is unproductive due to lack of available nitrogen. Generally, the upper soil profile is filled with live and dead roots, making it impermeable to water and low in productivity due to that lack of available nitrogen.

Soil Texture

Relative proportions of soil, clay, silt and sand in combination comprises the texture of the soil.


A grass seed head where the spikelets are attached directly to the stem (the rachis) without a stalk, e.g. wheatgrasses, cereal wheat.


A secondary spike. In grasses, this is a structure with one or more florets that usually have a pair of glumes at the base where they are attached to the stem (rachis).


A common term for a stem or similar structure that supports a plant part such as a flower, etc.


The plant structure that supports the branches and leaves of a plant.

Stocking Period

The duration of time that livestock are grazing in a paddock or pasture.

Stocking Rate

The number of livestock per area of pasture, usually expressed as animals or animal units per hectare or acre, but may be expressed as hectares or acres per animal unit.


The accumulation of the growth of a forage crop that can then be grazed at another time during the year, e.g. ungrazed summer regrowth to be grazed in the fall or winter.


A prostrate stem on or just below ground level, which produces shoots and roots at its nodes, enabling the plant to spread. White clover has stolons.


Subdivision or sub-member of a species, e.g. Flemish or Siberian alfalfa is a subspecies of the species alfalfa.



Natural, soluble compounds called polyphenols that are found in leaves, seed, etc. of many forage plants. Tannins condense with proteins to form a substance that is insoluble and low in digestibility. Tannins may reduce or eliminate bloat when grazing legumes.


A prominent central root from which branch roots or lateral roots develop.


A plant with four sets of chromosomes in its cells.


In grasses, a shoot forming at the base of the plant, which has a growing point that can produce leaves, stem, head and new buds. A grass plant may have several tillers.


Leaf margins that are serrated or notched.

Total Digestible Nutrients (TDN)

The total digestibility of the organic components in the forage.


Having three leaflets, e.g. clover.


Grass with its matted roots and rhizomes that hold the soil together.


Utilization Year

The year when perennial forage is well enough established to first be harvested is the first utilization year.



Made up of different colors. For example, some alfalfa varieties have flowers that are of variegated color.


See cultivar.


The freezing or cold treatment required by some plants to flower and produce seed, e.g. winter wheat, fall rye.


Warm-season Plants

A plant that grows best with warm temperatures (30 – 35° C). A 4 carbon acid is the first product leading to carbohydrate production during photosynthesis. C4 photosynthesis is more efficient than C3 photosynthesis (cool-season), but requires warmer temperatures. Corn is a warm-season crop.


Saturated with water, greater than its water-holding capacity.


A faint leaf mark, showing as a different color from the rest of the leaf, often V or crescent-shaped. Many of the common clovers, such as red and white clover, have a watermark on their leaves. It is useful in plant


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