SECONDARY GROWTH

ONLY FOUND IN DICOTS AND SOME MONOCOTS

DICOTS-   2 COTYLEDONS
          NET VEINED LEAVES
                          
MONOCOTS- 1 COTYLEDON
 
                    PARALLEL VEINED LEAVES

THE VASCULAR CAMBIUM

1. MADE UP OF TWO TYPES OF CELLS
        a. FUSIFORM INITIALS - PRODUCE SECONDARY PHLOEM AND XYLEM FOR
      LONGITUDINAL (UP AND DOWN MOVEMENT)

   XYLEM MADE UP OF TRACHEIDS AND VESSELS (DEAD WHEN FUNCTIONAL)

   1. TRACHEIDS ARE LONG AND SKINNY
        2. VESSELS ARE SHORT AND FAT

   PHLOEM MADE UP OF SIEVE TUBES AND COMPANION CELLS
       (BOTH LIVING WHEN FUNCTIONAL)

   1. SIEVE CELLS LACK A NUCLEUS
        2. COMPANION CELLS HAVE A NUCLEUS - DIRECT SIEVE CELLS

   b. RAY INITIALS - PRODUCE SECONDARY PHLOEM AND XYLEM FOR
      HORIZONTAL MOVEMENT

VASCULAR CAMBIUM ORIGIN

MADE FROM PROCAMBIUM CELLS

CONTROLLED BY HORMONES - AUXIN

       IN SPRING, CAMBIAL CELLS RESPOND TO AUXIN
       IN FALL, CAMBIAL CELLS DONíT RESPOND TO AUXIN

   VASCULAR CAMBIUM REACTIVATED YEAR AFTER YEAR

SECONDARY XYLEM: WOOD

FORMS TO THE INSIDE OF THE VASCULAR CAMBIUM

USED FOR LUMBER, PULP AND PAPER PRODUCTS

KINDS OF WOODS

1. SOFTWOOD - NONFLOWERING SEED PLANTS
       a. SPRUCE
       b. PINE
       c. FIR
       d. REDWOOD

   - HAVE RESINS
       - LIGHT WEIGHT
       - ONLY HAVE TRACHEIDS

2. HARDWOOD - FLOWERING SEED PLANTS
       a. OAK
       b. MAPLE
       c. WALNUT
       d. ASH

   - HEAVY
       - HAVE TRACHEIDS AND VESSELS

3. SAPWOOD
       a. OUTER FEW CMS OF WOOD
       b. SAP IS CONDUCTED

4. HEARTWOOD
       a. CENTER OF A TREE
       b. DUMPING GROUND FOR TREE

CUTS OF WOOD

1. CROSS SECTION

2. RADIAL SECTION

3. TANGENTIAL

PROPERTIES OF WOOD

1. KNOTS
2. GRAIN
3. TEXTURE
4. FIGURE
5. DENSITY
6. DUABILITY
7. WATER CONTENT

BARK: SECONDARY PHLOEM AND PERIDERM

SECONDARY PHLOEM FORMED TO THE OUTSIDE OF THE VASCULAR CAMBIUM

PERIDERM - REPLACES THE RUPTURED EPIDERMIS

MADE OF:

1. PHELLOGEN - CORK CAMBIUM

2. PHELLUM - CORK

3. PHELLODERM