By: Emily, Lauren, and Rebecca
Plant Structure, Growth, and Development
Plants• 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• 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_dominance.jpg
Leaf: 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
Leaves
The Three Tissue Systems: Dermal, Vascular, and GroundTissue System: where one or more tissues interact as a functional unitDermal 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• Vascular cylinder: the tissue that forms
a column in the roots• Vascular bundles: the stele in leaves
and stems
Ground Tissue SystemServes as filler, support and storage• Pith: the ground tissue that is in the
vascular tissue• Cortex: external ground tissue to
the vascular tissue
Plant GrowthIndeterminate 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 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...
Herbaceous: no wood (all primary growth)
Initials: the cells at the meristems that remain as meristems to continually produce new cellsDerivatives: cells that are produced by the apical meristems and become differentiated
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 Lengthens Roots and Shoots
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 LeavesThe 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
• 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
• 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!
• •
Genetic Control of Flowering
• Meristem identity genes
• ABC Model