Download Vascular Tissue System

Plant Structure, Growth, and
Development
By: Emily, Lauren, and
Rebecca
Plants
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Plasticity: where a plant is able to mold itself due its environment
Morphology: is the plants external form
Tissues: a group of cell with common function and structure
Organs: many tissues that work together to preform work
Protoplast: area of cell not including the cell wall (able to determine
function)
Plant Organs: Roots, Stems, and Leaves
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Root System: portion of plant responsible for
absorbing water and nutrients
Root: the organ that anchors the plant, absorbs
water and nutrients
Taproot v. Lateral roots:
• Taproot: the main vertical root which
developed from the embryonic root
(Taproot system)
• Lateral roots: or Branch roots which are
the roots coming off of the taproot and
acts as a storage area
• Fibrous Root System: usually has no
main root but a bunch of small roots
• Adventitious: where there is growth in
an unusual area
• Root hairs: small root
growth
Stems
• Stem: an organ of the plant that
support the leaves
• Nodes: where stem and leaf attatch
• Internodes: the segments of stem
between the nodes
• Terminal bud: embryonic tissue
located at the tip/top of the plant
• Axillary bud: the bud that is able to
form a branch
• Apical Dominence: where the
growth of the main stem (the
terminal bud) is dominant over the
apical buds
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/A/apical_do
minance.jpg
Leaves
eaf: organ that preforms photosynthesis
Petiole: joins the leaf to the stem
Blade: the flat part of the leaf

Vein: similar, but not as complex veins that are in
humans
The Three Tissue Systems: Dermal,
Vascular, and Ground
Tissue System: where one or more
tissues interact as a functional unit
Dermal Tissue System
• Epidermis: the outer protective layer in
plants
• Periderm: another protective layer that
replaces the epidermis
• Cuticle: the waxy coating
Vascular Tissue System
• Xylem: cells (mainly dead) that move
H20 and minerals up from the roots
• Phloem: transports sugar
• Stele: the vascular tissue in stem and
root
Ground Tissue System
• Vascular cylinder: the tissue that forms Serves as filler, support and storage
a column in the roots
• Pith: the ground tissue that is in the
• Vascular bundles: the stele in leaves
vascular tissue
and stems
• Cortex: external ground tissue to
the vascular tissue
Plant Growth
Indeterminate growth: continuous
growth in plants (during entire lifetime)
• Meristems: tissues that enable
plants to continuously grow
- Apical meristem: at tips and
roots
• Primary growth: the plant grows in
length
• Secondary growth: growth in
thickness (bark) (through lateral Herbaceous: no wood (all primary growth)
meristems)
• -Vascular cambian: secondary
layers of vascular tissues
• -Cork cambian: where periderm
replaces the epidermis (tougher)
Plant life
• Annuals: die in a year.
• Biennials: die in 2 years
• Perennials: live many years...
Initials: the cells at the meristems that remain as meristems to continually
produce new cells
Derivatives: cells that are produced by the apical meristems and become
differentiated
Primary Growth Lengthens Roots and
Shoots
Root Cap - protects the
apical meristem as the
root pushes through soil
during primary growth.
Growth occurs in three
zones of cells at
successive stages of
primary growth.
From the root tip up, the
zones are cell division,
elongation, and
maturation
Primary growth roots produces
the epidermis, ground tissue,
and vascular tissue.
Primary Growth of Shoots
leaves arise as leaf
primordia, finger–like
projections along the flanks
of the apical meristem
Eudicot vs. Monocot
Eudicots - the vascular tissue consists of vascular bundles arranged in
a ring. The xylem in each vascular bundle faces the pith, and the
phloem faces the cortex.
Monocot - the bundles are scattered throughout the ground tissue,
rather than forming a ring (Figure35.16b ). In both monocot and
eudicot stems, ground tissue consists mostly of parenchyma
Tissue Organization of Leaves
The epidermal barrier is interrupted by the stomata, which allow
CO2 exchange between the surrounding air and the
photosynthetic cells inside the leaf.
stoma - the stomatal pore consisting of a pore flanked by
two guard cells
Secondary growth adds girth to stems and
roots in woody plants
Secondary growth, the
growth in thickness
produced by lateral
meristems, occurs in
stems and roots of woody
plants.
The secondary plant
body consists of the
tissues produced by the
vascular cambium and
cork cambium.
The Vascular Cambium and Secondary Vascular Tissue
The vascular cambium is a
cylinder of meristematic cells
one cell thick. In this way, it is
primarily responsible for the
thickening of a root or stem.
In a typical gymnosperm or
woody eudicot stem, the
vascular cambium forms in a
layer between the primary xylem
and primary phloem of each
vascular bundle
heartwood - the older layers
of secondary xylem no
longer transport water and
minerals (xylem sap).
sapwood - The outer layers
still transport xylem sap.
Heartwood is generally
darker than sapwood
because of resins and other
compounds that clog the
cell cavities and help
protect the core of the tree
from fungi and wood–boring
insects.
Plant Body Production: Growth,
Morphogenesis, and Differentiation
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Morphogenesis: The development of body
form and organization. It's all about gene
expression and gggrrrrrrowth!
Systems Biology: An approach to studying
biology that aims to model the dynamic
behavior of the whole biological systems.
The most commonly studied plant
is Arabidopsis thaliana.
o The entire genome has been
sequenced!
o Mmm... Mustard
Growth
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Growth: Cell division increases potential for growth, but it is growth that
increases mass!
The plane of cell division affects the plantform:
• Parallel to previous= single file of cells
• On multiple planes= cube.
• Random= disorganized clump of cells.
• Asymmetrical Cell division: Uneven distribution of cytoplasm. Signals a key
event in development.
Growth
• Large vacuole: Water is 90% of
growth.
• The plan of cell division is
determined by the preprophase
band.
• Orientation determined by
cellulose microfibrils.
Morphogenesis and Pattern Formation
• Pattern formation: the development of specific structures in
specific places.
• Positional Information: Signals to which genes regulating
development respond, indicating a cell's location relative to
other cells in an embryonic structure.
• Polarity: the condition of having structural differences at
opposite ends of an organism.
Phase Changes=Plant Puberty!
• Phase changes: The
morphological changes that
arise from transitions from a
juvenile phase to an adult
phase.
o usually changes in the
leaves and stems
o juvenile meristems can
keep growing juvenile
shoot's and leaves if a node
forms... even after the
apical meristem is mature!
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Genetic Control of Flowering
• Meristem identity genes
• ABC Model