1. Lecture # Date _____
Chapter #35~ Plant Structure and Growth

2. Angiospermophytes: Flowering Plants!

3. Angiosperm structure Three basic organs: 1) Roots (root system)
fibrous: mat of thin roots
taproot: one large, vertical root
Branching and Root hairs increase surface area for mineral ion and water uptake.
2) Stems
axillary bud: between leaf and stem, potential to form branch shoot usu. dormant in young plants.
terminal bud: apex (tip) of young shoot, where most shoot growth occurs
apical dominance: terminal bud inhibits axillary bud growth (prune?)
3) Leaves
Blade (flattened)
Petiole (Stalk)

4. Angiosperms: MONOCOTS VS. DICOTS
(Seed leaf)
Mono vs. dicot
Fibrous root system taproot usu. present

5. Tissue Distribution in Dicot Stems
Vascular bundles (xylem and phloem)
Surrounded by ground tissue (xylem faces pith and phloem faces cortex in dicots)
Be able to draw and label!

6. Tissue distribution dicot leaf
Be able to draw and label!!

7. Primary Tissues of Leaves
Epidermis/cuticle (protection; prevents desiccation)
Stomata
Guard cells
Mesophyll: ground tissue between upper and lower epidermis
palisade (most photosynthesis)
spongy (gas circulation)

8. Structure and Function of leaves
Explain the relationship between the distribution of leaf tissues and their functions:
Absorption of light
Gas exchange
Support
Water conservation
Transport of water and products of photosynthesis

9. Modified roots, stems and leaves
Storage roots– roots swollen with food. (ex. Carrot)
STEMS
Stem tubers= parts of the stem that grow down into the ground and are used for food storage (ex. Potato)
LEAVES
Bulbs= leaf bases– used for food storage (ex. Onion, tulip)
Tendrils= outgrowths from leaves that allow plants to vine. (ex. Vining plants)

10. Dicots have…
Meristems (perpetually embryonic parts that make new cells for plant growth)
apical: tips of roots and buds; primary growth (height of plant)
lateral: cylinders of dividing cells along length of roots and stems; secondary growth (girth of plant);
Produce wood

11. Control of Plant Growth
Plant growth is controlled by hormones:
Ex. Auxin and phototropism
Other factors also affect growth… ex.

12. Terrestrial Plant Support
Thickened cellulose
Cell turgor
Lignified xylem (lignin– a hardening agent found in wood)

13. End of IB STUFF

14. Secondary Growth Two lateral meristems
(TREE RINGS)
Two lateral meristems
1. vascular cambium ~ produces secondary xylem (wood) and secondary phloem (diameter increase; annual growth rings)
2. cork cambium ~ produces thick covering that replaces the epidermis; produces cork cells; cork plus cork cambium make up the periderm;
lenticels (split regions of periderm) allow for gas exchange;
bark~ all tissues external to vascular cambium (phloem plus periderm)

15. Plant tissue Systems
Dermal tissue system (epidermis): single layer of cells for protection
Cuticle– waxy coating secreted by epidermis of leaves
Root hair epidermis used for absorption
Vascular tissue system (material transport)
xylem: water and dissolved minerals from roots to shoots
2 cell types: tracheids & vessel elements: elongated cells dead at maturity
phloem: food from leaves to roots and fruits
sieve-tube members: phloem tubes alive at maturity capped by sieve plates (porous); companion cells (nonconducting) connected by plasmodesmata to sieve tube member. P.681
Ground tissue system– makes up most of the young plant (photosynthesis, storage, support): pith and cortex

16. Plant Tissue Cell Types
Parenchyma primary walls thin and flexible; no secondary walls; large central vacuole; most metabolic functions of plant (chloroplasts)
Collenchyma unevenly thick primary walls used for plant support (no secondary walls ; no lignin– a hardening agent)
Sclerenchyma support element strengthened by secondary cell walls with lignin (may be dead; xylem cells);
Two types = fibers (long, occur in bundles) and sclereids (shorter, irregular, nutshells etc.)

17. Plant Growth Life Cycles annuals: 1 year (wildflowers; food crops)
biennials: 2 years (beets; carrots)
perennials: many years (trees; shrubs)
Meristems (perpetually embryonic)
apical: tips of roots and buds; primary growth
lateral: cylinders of dividing cells along length of roots and stems; secondary growth (wood)

18. Primary growth Roots root cap~ protection of meristem
zone of cell division~ primary (apical) meristem
zone of elongation~ cells elongate; pushes root tip
zone of maturation~ differentiation of cells (formation of 3 tissue systems)

19. Primary Tissues of Roots
Stele~ the vascular bundle where both xylem and phloem develop, (also, the entire collection of vascular tissue in roots and stems)
Pith~ central core of stele in monocot; parenchyma cells
Cortex~ region of the root between the stele and epidermis (innermost layer: endodermis)
Lateral roots~ arise from pericycle (outermost layer of stele); just inside endodermis, cells that may become meristematic

20. Leaf structure

21. Summary of primary & secondary growth in a woody a stem
PRIMARY PRIMARY LATERAL SECONDARY
MERISTEMS TISSUES MERISTEM TISSUES
Protoderm Epidermis Secondary
phloem
Primary phloem Vascular
Procambium cambium Secondary
Primary xylem xylem
Ground
meristem Ground Pith &
tissue: Cortex Cork
cambium Cork
Apical
meristem
of stem
Periderm

22. Hydrophyte Characteristics