1. Plant Structure

2. Hierarchy of a Plant Body
Extreme developmental plasticity in plants
Structurally change morphology, external form, to better suit environment
Genetic factors play small role too
More variety within plant species than animal species
Plants have organs that are composed of tissues that are made of cells
Basic organs are roots, stems, and leaves
Cabomba caroliniana, a fanwort

3. Hierarchy of a Plant Body
Plants aquires resources from 2 different environments
CO2 and light from above ground
Water and nutrients from soil
Plants have organs that are composed of tissues that are made of cells to facilitate
Basic organs are roots, stems, and leaves
Form root system and stem system
Systems rely on each other for materials

4. Roots An organ that anchors, absorbs, and store 3 types
Taproot system has 1 main vertical root that produces small lateral, or branched, roots
Most eudicots and gymnosperms; i.e. carrots and beets
Store sugars and starches for flowering; why root crops harvested before flowering
Adventitious roots arise from stems or leaves, with each forming separate lateral roots
Can be modified to provide more support of anchorage; fig. 35.4
Fibrous roots form a mat of thin roots that don’t penetrate deeply
Seedless vascular plants and most monocots; i.e. grasses
Root hairs found near the tips aid in absorption and increase SA
Short lived and constantly replaced, not to be confused with lateral roots

6. Stems
Alternating nodes where leaves attach and internodes, the segments in between
Upper angle of each leaf contains an axillary bud which can form a lateral shoot, but are normally dormant
Near the shoot tips are apical buds which inhibit axillary bud growth via apical dominance
Concentration of resources so plant can grow taller
If apical bud is gone then axillary buds can develop into lateral shoots and become their own apical bud
Reason for pruning bushes and trimming house plants

7. Leaves Main photosynthetic part of the plant
Consist of a flattened blade and a petiole or stalk to join to stem at node
Veins, the vascular tissue, differ in arrangement between eudicots and monocots
Monocots with parallel veins
Eudicots with branched veins
Angiosperms classified by vein branching (floral morphology too)
Simple have single undivided blades
Compound blades of multiple leaflets (apical at base of blade only)
Adaptations for support, reproduction, or storage

8. Leave Patterns and Deviations

9. Tissue Systems Dermal tissue system is the outer protective covering
Nonwoody plants have an have an single layer of epidermis that covers and protects young parts of a plant
Secretes a waxy cuticle covering to help retain water
Woody plants have a periderm to protect older regions of plant
Vascular tissue system runs throughout the plant
Xylem transports water and minerals up
Phloem transports food down to where its needed
Collectively know as stele
Angiosperms have solid central vascular cylinder, leaves and stems have vascular bundles, separate strands of vascular tissue
Ground tissue system
Internal to vascular is called pith, external is cortex

10. Plant Cell Types
Parenchyma cells: thin and flexible primary walls, lack secondary
‘Typical’ plant cells because they are least specialized
Perform most of the cell’s metabolic functions
Can regenerate a whole plant from one cell
Collenchyma cells: thicker primary walls, but unevenly thickened
Grouped as strands or cylinders to support young parts of shoots
i.e. strings of celery
No secondary walls or lignin
Sclerenchyma cells: thick secondary walls strengthened by lignin
Can’t elongate and reside in parts of plants no longer growing
Most dead at maturity, but produce the secondary cell wall before for support
Fibers are long and slender; hemp fibers to make rope and flax fibers wove into linen
Sclereids irregular in shape and are shorter; impart hardness to nutshells and seed coats
Xylem
Phloem