What are primary and secondary the functions of roots?
Primary
- absorption
- anchorage
Secondary
- Conduction
- storage
- vegetative reproduction
What are the two root systems? How do they differ?
Diffuse Root System
- Several or many main roots.
- Slender
- Uniform size
- Numerous branches
- ex. corn, wheat, grasses, sweet potatoes
TAP ROOT
-one primary root
What is the scientific name for the primary root
The radicle
Think radish. Radicle radish…
What are the root elements in order from the tip and up?
Briefly describe their functions.
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
What is the function of root hairs?
Increase absorptive surface area by up to 20 times
Absorb water and dissolved mineral salts in soils
What are the layer of a standard root starting at the outside?
Briefly describe their makeup
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
What are the three root types? Briefly describe
Primary Root
-arises from radicle
Secondary Roots
-Arises from primary root
Adventitious Roots
-Roots arising from a shoot system
Name some types of adventitious roots
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.
What are the three root tissues?
Protoderm
-epidermis and root hairs
Ground meristem
- cortex
- storage and lateral water movement
Procambium
What are miccorhizae? What kind of relationship do they have with trees?
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.
What are root nodules?
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)
Where do lateral roots form from the…
Pericycle
3 styles of tree roots?
Tap root
Heart root
Shallow roots
