Vegetative Anatomy of Crop Plants
Thomas G Chastain
CROP 200 Crop Ecology and Morphology
Vegetative Anatomy
• Stems provide support for leaves, flowers, and fruit.
The shoot system is made up of stems and leaves.
• Leaves are the principle photosynthetic organs of
higher plants.
• Roots are hidden but may account for 1/3 of the
total plant weight.
Shoot and root system of a tall fescue plant
Leaf
• Simple Leaves - Leaves with one
blade are known as simple leaves.
• The blade of a leaf is known as the
the lamina.
• The support stalk of a leaf is called a
petiole.
• When the leaf has no petiole it is
known as a sessile leaf.
Examples of simple leaves, young
canola plant (top), and cucumber
(bottom)TG Chastain photos
Lamina
Petiole
Leaflet
Petiolar Branch
Petiole
Potato leaf (TG Chastain
photo)
Leaf
• Compound Leaves - Leaves with
two or more blades are called
compound leaves.
• Each blade on a compound leaf is
called a leaflet.
• The stalk of a leaflet is called a
petiolule or petiolar branch.
Leaflet
Tendril
Stipule
Leaf
• Compound Leaves - When the
compound leaf has three leaflets
it is known as a trifoliolate. Many
legumes have this type of leaf.
• The stipule is a leaf-like growth
found at the base of the petiole.
Stem
Trifoliolate
Pea leaf and stipule (TG
Chastain photos)
Stems and Branches
• Function of stems and branches:
1. Provide support for leaves, flowers, and
fruit.
2. Connect leaves, flowers, and fruit with
water and nutrients moving up from the
root. Connect roots with above-ground
food producing (photosynthetic) organs.
3. Carbohydrate storage.
4. Carbohydrate production via
photosynthesis.
Canola stems (top), sunflower main
stem and branches (left). TG
Chastain photos
Stems and Branches
Kentucky bluegrass
plant, stolon (bottom
right) TG Chastain
photos
Leaf
Tiller
Rhizome
Mainstem
Roots
• The tiller is a branch on a grass
plant.
• Rhizomes are specialized
stems which grow horizontally
below the soil surface and
eventually turn upward. At the
point where the rhizome
emerges from the soil, a new
plant, genetically identical to
the parent plant is formed.
• Stolons are horizontal, aboveground stems.
INTERNODE
Grass stem and leaf structure
(top), corn stem and leaf (right)
TG Chastain photo
Stems and Branches
• The node is the part of the stem
where the leaves are attached.
• The internode is the region
between the nodes.
Stems and Branches
• The shoot apical meristem or
SAM and the intercalary
meristem are the two
primary sites of stem growth
and developmental activities.
• In dicots, stem development
and branching results from
the activity of the apical
meristem.
Typical SAM of dicots
Stems and Branches
• The shoot apical meristem in
monocots, such as the grasses, is
hidden within the stem and is the
source of new leaves and tillers.
• The crown is the part of the plant
where the shoot system (tillers)
meets the roots.
Tiller
Crown
Roots
Location of SAM in grasses (top left),
crown of grass plant (bottom left) TG
Chastain photo
Stems and Branches
• The intercalary meristem is
responsible for the elongation
of the stem (internode) and is
located at the base of the
internode region.
Time
Longitudinal section of grass stem showing
location of intercalary meristem and it’s
impact on stem elongation in grasses
Stems and Branches
• Tubers are not roots, they
originate from stolon tips. Tubers
are important organs for the
storage of starch.
Stolon
New Tuber
Potato tuber (top), stolon with
developing tuber (bottom) TG
Chastain photos.
Roots
• The primary functions of plant
roots are to:
1. Anchor the plant
2. Absorption of water and
nutrients
3. Food storage
Grass roots with root
hairs (TG Chastain photo)
Roots
• In some crop plants, roots are a
strong sink for the accumulation of
carbohydrates and are the unit of
economic yield for which the crop
is managed.
• Examples include carrot, radish,
yam, and beet.
Root Development
Secondary
roots
Primary root
• The first root to develop from the
apical meristem at the root end
of the embryo (radicle) is known
as the primary root or taproot.
• In dicots, the taproot axis and the
branched secondary roots
(laterals) make up the root
system. This pattern of root
development forms a taproot
system.
Root Development
• In monocots, the primary root is
short lived and the root system is
formed by adventitious roots
arising from the shoot. This type
of root development forms a
fibrous root system.
• Seminal roots arise from 2 nodes
in the seed. These include the
primary root axis (arising from
the radicle) and up to 5 other
root axes.
• Crown or nodal roots are
associated with tillers and the
mainstem.