Glossary

Apical meristem
A special restricted area of growth which is established at the time of early embryo development. Growth of the tips of stems or roots occurs from apical meristems. In grasses, new leaves are produced from apical meristems.

Cool Season
Grasses that begin growth (tiller elongation or green-up) during the early spring, often when soil temperatures are around 45 degrees Fahrenheit, and complete their life cycles before hot summer weather. These are also referred to as C3 plants. These plants make a three-carbon compound as the first stable product of carbon fixation; more than 95% of the earth’s plant species can be characterized as C3 plants.

Deferment
Delay of livestock grazing on an area for some period of time beyond the beginning of the growing season, usually to allow for seed production, establishment of new plants or growth of existing plants. Generally defined as the delay of grazing until the seed of the key forage species is mature. Contrast with rest.

Defoliation
The removal of physiological active plant material, whether by grazing, mowing, burning or other means.

Floret
A special term for a grass flower.

Glumes
Scale-like bracts at the base of the spikelets.

Inflorescence
The flowering part of a plant, when not solitary. In grasses, this includes the spikelets and the branches bearing them.

Intensity
The proportion of the current year's biomass production that is removed from a single plant, a species or the vegetation.

Internode
The portion of a stem between two successive nodes.

Node
The place on a stem where leaves or branches normally originate; often swollen or knob-like in grasses. See figure 1b.

Origin
Refers to the country of origin of the species; if the plant species was believed to have been present before European colonization it is referredto as a Native. If the plant was introduced in some way subsequent to European colonization it is referred to as Introduced.

Rest
When used in reference to grazing systems, rest refers to restricting access of grazing animals from an area or pasture for an entire growing season. The term can refer to prolonged non-disturbance to soils and plant communities.

Spikelet
The unit of the inflorescence in grasses comprising usually two glumes and one or more florets.

Season
Refers to the season of primary growth of the species. Grasses can be either Cool Season (C3) plants or Warm Season (C4) plants. Some Warm Season grasses can produce significant growth earlier than others. For example, sideoats grama will produce more green biomass in the spring than will blue grama.

Season of use
Refers to the period of grazing in relation to phenological development of the plant.

Tiller
A shoot from an adventitious bud at the base of a plant. In grasses these comprise several units, each consisting of a leaf blade and sheath, collar, ligule and axillary bud.

Utilization
Similar to defoliation only used in reference to intensity of defoliation by herbivores, usually over an entire grazing period and expressed in relation to total above ground biomass production for that year.

Warm Season
Grasses that begin growth (tiller elongation or green-up) during the summer growing season, after soil temperatures warm to about 65 degrees Fahrenheit. These grasses are considered C4 plants, which utilize a different pathway than C3 plants, and make a four-carbon compound during initial carbon fixation. Less than 1% of earth’s plant species can be characterized as C4 plants.