Parts of a Grass Plant, reprinted
from 100 Native Forage Grasses in
11 Southern States by Horace L. Leithead, Lewis L. Yarlett,
and Thomas N. Shiflet, range conservationists. US Department of
Agriculture, Soil Conservation Service, Agriculture Handbook No.
389. (Technical information developed by the Federal government
is generally in the public domain and is not copyrighted.)
see photographic examples, click one of the cameras in the list of
parts of a grass plant are roots, stems, and leaves.
The flowering (reproductive) part is the seedhead.
and drawings of these parts follow :
are fibrous. Size of the root system depends on genetic and environmental
factors and on management. In general, grasses that are capable
of producing the greatest top growth are also capable of producing
the greatest root growth. The ratio of roots to tops by weight ranges
from about 0.8 :1 to 1.5 :1 for most native grasses.
influencing root growth are moisture, temperature, structure, depth,
fertility, and chemical reaction. Soil moisture, generally, has
the greatest effect on root depth. In shallow soils, root systems
are shallow; in moist, deep, well-developed soils, root systems
are deep. Grasses differ widely in their ability to grow in saturated,
poorly aerated soil. Excessive wetness inhibits root growth of most
grasses except those adapted to marshes.
affects the growth of grass roots. In general, native perennial
grasses have active root growth in the fall until frost, very slow
growth through winter, and active growth again in spring from about
10 to 15 days before green leaves appear until flowering. After
flowering, growth slows down and stops during summer when soil temperatures
The amount and
frequency of top-growth removal by grazing or mowing have a marked
influence on root growth. According to research (Crider, 1955),
the proportion of roots that stop growing varies according to the
proportion of top growth that is removed.
stem (culm) of a grass plant consists of nodes and
internodes. The nodes (joints) are solid and usually
larger than the rest of the stem. The internodes, the part
of the stem between two nodes, are usually hollow.
the base of the main stem may produce erect shoots; horizontal,
above-ground stolons (stoloniferous)
; or horizontal, below-ground rhizomes (rhizomatous). Both
rhizomes and stolons bear roots at the underside of the nodes.
of grasses branch only at or near the base from axillary buds at
the basal nodes. Others branch and rebranch from buds produced at
upper nodes, giving the appearance of a dense bouquet.
are stems or runners that originate at the base of the main stem
and grow along the surface of the ground. They have nodes and scales
or well-developed leaves. Roots borne at the nodes help to establish
and spread the plant and to produce new plants if stolons are broken.
are stems that originate at the base of the main stem and grow horizontally
below the ground surface. They have nodes, internodes, and scalelike
leaves. Roots grow from the underside of the nodes; shoots (stems
and leaves) grow from the topside.
Stems of most
perennial grasses die back to the approximate base of the stem each
year. However, in the basal part of the stem, there are from several
to many basal nodes with axillary buds capable of initiating new
are borne at nodes along the stem in two ranks. The newest leaf
is always on the opposite side of the stem from the leaf just below
it. Leaves are parallel-veined.
The grass leaf
consists of three principal parts: Blade, sheath, and
ligule. Other parts are collar and auricle.
the expanded part of the leaf may be
(2) V-shaped or folded,
(3) involute (rolled inward),
(4) filiform (threadlike), or
(5) keeled (boat shaped).
But it may grade
from one form to another.
sheath is borne at the node and surrounds
the stem like a tube. It is characteristically split down one side,
making it possible to separate the sheath from the stem without tearing
the sheath. In some grasses, the sheath is open the margins
do not come together; in others, it is closed-the margins overlap.
Some sheaths are flattened; others are rounded. Because of their different
forms and shapes, they are important in identifying a grass.
ligule, meaning little tongue, usually
clasps the stem firmly on the inside of the leaf at the junction of
the sheath and blade, preventing dirt and water from getting between
them. In the absence of a seedhead, the ligule is often used to identify
a grass. Some ligules are membranous or papery; some are only a ring
is on the outside of the leaf at the junction of sheath and blade.
have two earlike lobes or appendages, called auricles, which
are borne, one on either side, at the base of the blade.
(inflorescence) is the flowering (reproductive) part of the
grass plant. Generally, the seedhead has no leaves. On some grasses,
a sheathlike bract, called spathe, encloses or partly encloses
spikelet is the basic unit of the seedhead. It may be
pediceled (on a pedicel or footstalk) or sessile (without
consists of a rachilla (jointed stem or axis), one
to several florets, and two glumes.
are borne in two ranks on the rachilla.
them are the glumes two bracts without flowers.
consists of one flower or seed enclosed in two papery membranes
called lemma and palea.
is borne on the rachilla above the pair of glumes and the
palea at the base of the flower or seed.
glumes and lemma have nerves or veins that run from
the base to the tip. If the center nerve is extended, it is
called an awn. Because awns are of different lengths,
shapes, and colors, they are often used to identify a particular
The basic forms
of grass seedheads are spike,
raceme, and panicle but they may grade from one form
to another and may have specialized forms.
is a seedhead in which one or more sessile spikelets are borne on
the main axis (rachis).
is a seedhead in which the spikelets are borne on individual footstalks
(pedicels) growing directly on the main axis (rachis).
is a seedhead with a main axis and subdivided branches. It may be
compact and spikelike or open.