1. 13B-3 Roots Not always underground Anchor the plant
Absorb water and minerals
Some do food storage

2. Root systems Taproot system
Primary root continues to grow as the main root
Has secondary branching roots
Ex. Carrot

3. Root systems Fibrous root system Many secondary roots
Not one main root
Found in monocots.

4. Growth
Primary growth (in length) takes place in the meristematic region near tip of root
Does mitosis (see diagram)
Root cap- dead cells, push through soil, protects the root

5. Growth Elongation region
Above meristematic region, cells elongate (provides length)
Cells begin to differentiate and become various root tissues
Maturation region- most differentiation takes place

6. Tissues of root Primary tissues formed during primary growth
Epidermis with root hairs (extensions of epidermis) increase surface area
Cortex- inside of epidermis, stores minerals
Endodermis
One cell layer thick, inside cortex
All incoming substances must pass through it to enter rest of plant (endodermis controls what can enter)

7. Tissues of root Vascular cylinder- center of young root
Vascular cambium- makes additional xylem and phloem (secondary growth)
Pericycle- will produce secondary root & growth in diameter

8. 13 B-4 stems Woody or herbaceous Woody (tree trunk)
Herbaceous – green, live for one year, rely on turgor pressure

9. 13 B-4 stems Function of stems
1. manufacture, support and display leaves
2. conduct materials to and from leaves

10. 13 B-4 (Draw them to remember)
Branching patterns
1. Excurrent = apical dominance (grows tall first and suppress wide then grow wide later) Ex. pine tree
2. Deliquescent = apical dominance only when young (then lateral buds more active & main stem branches repeatedly) Ex. Mango tree
3. Columnar = unbranched stem with crown of leaves Ex. Coconut tree

11. Apical meristem: cells become leaves, stem tissues, & flowers
Apical bud: at end of twig
Lateral buds: on sides
Dormant buds: survive through winter
Bud scales: protect tiny leaves, fall off & leave bud scale scars

12. Nodes: place on stem where leaves produced
Lenticels: openings for gas exchange
Leaf scars: where petiole (or leaf) was attached

13. Growth of Woody Stems
Cork cambium: makes cork to protect stem (under epidermis)
Pith: inside xylem, largest area of young stem, stores/conducts materials, is central material
Vascular rays: from central pith horizontally outward, conduct water

14. Growth of Woody Stems
Wood: secondary xylem, made by vascular cambium during growing season
Springwood: lighter color Annual ring
Summerwood: darker
Sapwood: functional
Heartwood: dead xylem filled with chemicals, hard

15. Inner bark: phloem & cortex
Bark: tissues from vascular cambium outward, protective covering on tree
Inner bark: phloem & cortex
Outer bark: cork expands & cracks, textured
Lenticels: opening for oxygen

16. Girdling: strip off a section of bark all the way around
tree will die because phloem is disrupted
Sugars can’t go down to roots, water can still go up but roots eventually die

17. Herbaceous Dicot & Monocot Stems
Stem cortex is photosynthetic, retains epidermis
Vascular tissues not in concentric circles but found as fibrovascular bundles (usually at edges of stem)
In some (bamboo) pith disappears  hollow stem