Grass Growth and Regrowth for Improved Management

Grass Structures - Definition

Nomenclature of Vegetative and Floral Structures Grass Diagram 1

Knowing the names of specific plant parts will provide a foundation for in-depth discussions of mechanisms which account for growth and recovery following defoliation. The diagram and definitions are divided into three categories: vegetative, floral (reproductive), and collar. During early growth, while a grass plant is vegetative, identification is difficult. When floral structures are visible, identification is easier. The collar region is helpful for identification and it contains a band of intercalary meristem which, when properly safe-guarded, will account for regrowth following mowing or grazing.

Vegetative Structures

Notice the following labeled items on the drawing:

  • collar region: The collar region of the leaf is the most useful area for identifying vegetative-stage grasses. Later on, after seed head emergence, floral structures may provide a more obvious means of identification. The collar region consists of the leaf blade, the leaf sheath wrapping around the stem, auricles (if present), a ligule, and connective tissue called the collar. Each species is unique with respect to the presence, size, and shape of the auricles and ligules in this leaf zone. The collar (connective tissue) is a narrow band of intercalary meristem (tissue capable of growth) which accounts for blade growth. With immature blades, this meristem provides for further blade growth following defoliation.
  • The first photographs show a collar with the blade (lamina), auricles, ligule, and leaf sheath.

    • blade (lamina): part of the leaf above the collar
    • collar: a thin band of meristematic tissue at the junction of the leaf blade (lamina) and the sheath
    • auricles: claw appendages at the base of the blade of some grasses (some grasses do not have auricles)
    • ligule: outgrowth at the inner junction of the leaf sheath and blade, often membraneous, sometimes a fringe of hairs
    • sheath: lower part of the leaf that encloses the internode

    The middle photograph shows the collar, where intercalary meristematic tissue is seen (lighter in color) just underneath the top leaf blade. The lower leaf blade is bent back showing the ligule but a portion of whitish collar can be seen at the edge of the fold.

    The bottom photograph shows the collar, the narrow band of meristematic tissue of a timothy plant.

     Collar
    New_Collar
    Timothy Collar

    The collar region is also important in grass management. When properly safe-guarded, this band of intercalary meristem will account for continued blade growth following mowing or grazing of immature leaf blades.

    Floral Structures

    © 2000 Oregon State University.