1. Roots Framework of relatively large, woody, long-lived roots
Supporting a mass of small, short-lived non-woody absorbing roots

2. The Power of Roots

3. What Do Roots Do? Anchor the tree (whole root system)
Store sugars (larger roots)
Generation of vegetative shoots (e.g., aspen)
Production of some growth hormones
Prevent soil erosion
Absorption of water & minerals from soil (fine roots)
Regulate water loss(?)

4. Root Buttresses
The buttress provides support on the thin, old and highly weathered tropical soils. Decomposition is very rapid in the tropics, so having roots near the surface where the action takes place is crucial for effectively competing for the available nutrients.

5. We used to think that the primary reason for knees was respiration, but now it’s assumed their more for support.

6. Three types of roots Fibrous root Adventitious root Tap root
Forms from the radicle
Early stability in seedlings
Survival (dry and fire-prone sites)
Common in pines and species with large seeds with much food reserve (oaks, hickories, chestnuts, walnuts)
Fibrous root
Most common type of root
Typically slender
Branches and re-branches
Adventitious root
Form from shoot tissues.
Often arise after injury to roots OR from main stem, branch, etc.
Examples are those formed on stem/leaf cuttings & stilt roots

7. Tap Roots Tap root is one large central root. B:intermediate water
C: reaching to water table
D: low water growing lots of roots to meet its needs

8. Three types of roots Fibrous root Adventitious root Tap root
Forms from the radicle.
Early stability in seedlings
Survival (dry and fire-prone sites)
Common in pines and species with large seeds with much food reserve (oaks, hickories, chestnuts, walnuts)
Fibrous root
Most common type of root
Typically slender
Branches and re-branches
Adventitious root
Form from shoot tissues.
Often arise after injury to roots OR from main stem, branch, etc.
Examples are those formed on stem/leaf cuttings & stilt roots

9. Fibrous Roots
The exposed fibrous roots are not typical.

10. Three types of roots Fibrous root Adventitious root Tap root
Forms from the radicle.
Early stability in seedlings
Survival (dry and fire-prone sites)
Common in pines and species with large seeds with much food reserve (oaks, hickories, chestnuts, walnuts)
Fibrous root
Most common type of root
Typically slender
Branches and re-branches
Adventitious root
Form from shoot tissues.
Often arise after injury to roots OR from main stem, branch, etc.
Examples are those formed on stem/leaf cuttings & stilt roots

11. Adventitious Roots
Mangrove roots are primarily for oxygen uptake.

12. Root Form
Form and structure of the root system is primarily genetically controlled
Nevertheless, site conditions markedly influence the form and pattern of root development
This goes back to the discussion on genotype (genetic heritage) and phenotype (environmental influence on genotype).

13. Root System Architecture
Heart system- many horizontal and vertical roots
Plate or sinker system- large lateral roots and some smaller vertical roots
Taproot system- one major central root and smaller horizontal and vertical roots

14. Roots: Horizontal Distribution
Depends upon stand density & competition
Often 2-5 times the crown extension!

15. Roots: Vertical Distribution

16. Root Morphology {
Cortex
Vascular
Cambium
Endodermis
Phloem
Xylem
Cortex = several layers of relatively large, thin-walled living cells with intercellular air spaced forming interconnected air channels
seem to be essential for internal aeration. Suberin is a principal component of the outer cell walls of all underground organs and is associated with the cork cells of the periderm, the tissue that forms the outer bark of stems and roots during secondary growth of woody plants.

17. Root Morphology

18. Root Forms Suberized (permanent roots)
Outer tissue is dead bark
HOLD THE TREE UP!!!
Unsuberized (< 1 mm diameter, white)
Live 1-3 months
Only 1-5% of root biomass, BUT 90% of root surface area
DO THE WORK!!!
Coarse roots are suberized – hold the tree up and store nutrients.
Unsuberized
live 1-3 months – then either die or suberization occurs
absorb nutrients and water 100 times faster