Root System

Question 0

What are primary and secondary the functions of roots?

Answer 0

Primary

• absorption
• anchorage

Secondary

• Conduction
• storage
• vegetative reproduction

Question 1

What are the two root systems? How do they differ?

Answer 1

Diffuse Root System

• Several or many main roots.
• Slender
• Uniform size
• Numerous branches
• ex. corn, wheat, grasses, sweet potatoes

TAP ROOT
-one primary root

Question 2

What is the scientific name for the primary root

Answer 2

The radicle

Think radish. Radicle radish…

Question 3

What are the root elements in order from the tip and up?

Briefly describe their functions.

Answer 3

Root cap

• Protects vulnerable meristematic region
• Slippery due to rupturing of cells as the root grows. (aids penetration)

Meristematic region

• Mass of small cubical cells with thin walls and dense protoplasm
• Region where new cells are formed by mitosis
• functions in primary growth

Elongation region

• Recently formed cells undergoing enlargement (length)
• New protoplasm formed when vacuoles expand

Maturation

• Enlarged cells differentiate into mature tissue (Xylem/Phloem)
• Area of ROOT HAIR generation

Question 4

What is the function of root hairs?

Answer 4

Increase absorptive surface area by up to 20 times

Absorb water and dissolved mineral salts in soils

Question 5

What are the layer of a standard root starting at the outside?

Briefly describe their makeup

Answer 5

Epidermis
-Surface layer of cells
-Absorbs water and dissolved minerals from the soil and offers some protection to inner root.
Cortex
-Irregular parenchyma cells
-Mainly water and food storage
-Between epidermis and endodermis
-Radial walls thickened with suberin for water proofing
Endodermis
-separates cortex from pericycle
Pericycle (root equivalent of intrafascicular parenchyma)
-As roots mature, cambium develops between xylem and phloem to increase root diameter
-gives rise to secondary roots
-meristematic
Xylem
-Composed of vessels (angio), tracheids (gymno), fibers and parenchyma.
-Conducts water and minerals upward
Phloem
-Sieve tubes, companion cells alternating with radial xylem bands
-Parenchyma
-functions in Downward conduction of food

Question 6

What are the three root types? Briefly describe

Answer 6

Primary Root
-arises from radicle

Secondary Roots
-Arises from primary root

Adventitious Roots
-Roots arising from a shoot system

Question 7

Name some types of adventitious roots

Answer 7

Prop roots (Aerial roots)
- provide aerial support
Stolon
- roots that form from nodes on stems where the root is near the ground.
Rhizome
-Horizontal, below ground stem.

Question 8

What are the three root tissues?

Answer 8

Protoderm
-epidermis and root hairs

Ground meristem

• cortex
• storage and lateral water movement

Procambium

Question 9

What are miccorhizae? What kind of relationship do they have with trees?

Answer 9

Underground mycelium that branch out in a root like pattern, interacting with and even connecting tree’s roots.

Form a symbiotic relationship with roots.
Enhance uptake of n2 and P to tree in return for sugars. Provide tree with nutrients during times of need.

Question 10

What are root nodules?

Answer 10

Bacterial association where atmospheric N is converted to ammonium nitrate that can be absorbed by the tree in return for sugars.

Common on red alder (rhizobium bacteria)

Question 11

Where do lateral roots form from the…

Answer 11

Pericycle

Question 12

3 styles of tree roots?

Answer 12

Tap root

Heart root

Shallow roots