ROOT SYSTEMS

          1. TAPROOT SYSTEM - FOUND IN CONIFERS AND DICOTS
                 
       RADICLE THAT EMERGES FROM A
SEED FORMS A PROMINENT TAP-
                  ROOT THAT PERSISTS THROUGHOUT THE LIFE OF A PLANT.
                 (EX. CARROT, BEET)

       BRANCH ROOTS GROW FROM THE TAPROOT

       TAPROOTS CAN BE:

       1. MODIFIED FOR STORAGE (CARROTS, BEETS)
       2. MODIFIED FOR REACHING WATER DEEP IN THE GROUND

       BRANCH ROOTS CAN TAKE OVER FOR THE TAPROOT IF IT IS
       DAMAGED

   2. FIBROUS ROOT SYSTEM - MONOCOTS (GRASSES)

               CONSISTS OF A MASS OF SIMILAR SIZED ROOTS

               RADICLE IS REPLACED BY ADVENTITIOUS ROOTS (ROOTS
               NOT ARISING FROM OTHER ROOTS)

      ARE EXCELLENT IN PREVENTING SOIL EROSION

      SOME ARE MODIFIED FOR STORAGE

      1. IPOMOEA BATATAS - SWEET POTATO

   3. ADVENTITOUS ROOTS - ARISE FROM PLANT PARTS.

      CAN GROW FROM THE NODES OF SHOOTS OR FROM PLACES ON
               THE LEAVES AND PETIOLES

      OFTEN FORM AT THE CROWN OF A PLANT

      THE CROWN IS WHERE THE STEM AND ROOT COME TOGETHER

FUNCTIONS AND STRUCTURES OF ROOTS

FOUR (4) PRIMARY FUNCTIONS:

1. ANCHORAGE - KEEP PLANT IN A SINGLE SPOT FOR LIFE
2. STORAGE - STORE FOOD RESERVES FOR THE PLANT
3. ABSORPTION - ABSORB LARGE AMOUNTS OF WATER AND
       NUTRIENTS
4. CONDUCTION - TRANSPORT WATER AND DISSOLVED NUTRIENTS TO AND
   FROM THE SHOOT

STRUCTURE

1. ROOT TIP -COVERED BY A ROOT CAP THAT IS MADE UP OF CELLS
   HAVING STARCH GRAINS

   THE STARCH GRAINS SETTLE IN RESPONSE TO GRAVITY, "TELLING"
   THE ROOT WHICH WAY IS DOWN

   IF YOU REMOVE THE ROOT CAP, THE ROOT DOES NOT KNOW WHICH
   DIRECTION TO GROW

   CELLS OF THE ROOT CAP ARE CONSTANTLY BEING RUBBED OFF
       AND REPLACED BY NEW CELLS

   SECRETE MUCIGEL WHICH IS MADE BY DICTYOSOMES

MUCIGEL CONTAINS:

1. SUGARS
2. ORGANIC ACIDS
3. VITAMINS
4. ENZYMES
5. AMINO ACIDS

MUCIGEL FUNCTIONS IN:

1. PROTECTION FROM:
       a. DESICCATION
       b. FROM THE ROOTS OF OTHER PLANTS
              - MAY SECRETE CHEMICALS THAT INHIBIT OTHER PLANTS ROOTS
2. LUBRICATION
3. WATER ABSORPTION
       a. SOIL PARTICLES STICK TO MUCIGEL
4. NUTRIENT ABSORPTION -
       a. MAY ATTRACT NITROGEN FIXING BACTERIA

QUIESCENT CENTER - LOCATED JUST UNDER THE ROOT CAP

   a. CONSISTS OF 500-1000 INACTIVE CELLS
        b. SERVES AS A RESERVE FOR CELLS TO REPLACE THE
               APICAL MERISTEM IF THE A.M. IS DAMAGED

2. SUBAPICAL REGION - DIVIDED INTO THREE REGIONS

A. ZONE OF CELL DIVISION -CONTAINS THE APICAL MERISTEM
       1. SMALL CELLS
       2. DENSELY CYTOPLASMIC

B. ZONE OF CELL ELONGATION
       1. ELONGATE BY FILLING VACUOLES WITH WATER

C. ZONE OF CELLULAR MATURATION
       1. CELL DIFFERENTIATION
       2. ROOT HAIR FORMATION
       3. MATURE REGION

BEHIND THE ZONE OF MATURATION

   a. EPIDERMIS - ONE CELL LAYER THICK, DIFFERENTIATES FROM
      THE PROTODERM, LACKS CUTICLE AND STOMATES

   b. CORTEX - UNDER EPIDERMIS, FORMED FROM THE GROUND
      MERISTEM, MADE UP OF THE:

      1. HYPODERMIS - SUBERIZED PROTECTIVE LAYER OF CELLS
      2. STORAGE PARENCHYMA - THIN WALLED CELLS CONTAINING
         STARCH, LOTS OF AIR SPACES
               3. ENDODERMIS - PACKED TIGHTLY TOGETHER AND CONTAIN A
         SUBERIZED CASPARIAN STRIP.

WATER MOVEMENT INTO AND OUT OF A PLANT

MOVEMENT OF WATER INTO A ROOT CAN OCCUR IN ONE OF TWO WAYS:

1. APOPLASTICALLY
       a. MOVEMENT THROUGH CELL WALLS AND INTERCELLULAR SPACES

2. SYMPLASTICALLY - MOVEMENT THROUGH MEMBRANES AND LIVING
   CELLS

THE STELE - ALL TISSUES INSIDE THE CORTEX

1. PERICYCLE
2. VASCULAR TISSUES

PERICYCLE

1. LAYER OF PARENCHYMA CELLS ONE CELL LAYER THICK

2. MERISTEMATIC
       a. SITE OF ORIGIN OF LATERAL ROOTS

VASCULAR TISSUE

1. COMPOSED OF XYLEM AND PHLOEM
2. XYLEM AND PHLOEM ALTERNATE

MODIFIED ROOTS

1. STORAGE (BEETS, TURNIPS,RADISH, CARROT)
2. PROPAGATION (GIVE RISE TO NEW PLANTS)
3. AERATION (PNEUMATOPHORES)
       IMPORT OXYGEN FROM THE ATMOSPHERE. EXTEND INTO THE
   ATMOSPHERE 
TO COLLECT OXYGEN FOR THE ROOTS. COMPOSED OF
       AERENCHYMA.
4. NUTRITION
       a. PARASITISM - PARASITIZE OTHER PLANTS TO GET NUTRIENTS
       b. MYCORRHIZAL ROOTS

      MYCORRHIZAE IS A FUNGUS THAT FORMS A SYMBIOTIC
      RELATIONSHIP WITH ROOTS TO INCREASE THE ROOTS SURFACE
      AREA. MUTUALISM

   c. NODULES - CAUSED BY BACTERIA ASSOCIATED WITH ROOTS IN
      THE PEA FAMILY

      INTERIOR RED IN COLOR BECAUSE OF THE PRESENCE OF
      LEGHEMOGLOBIN.

OTHER ROOTS

AERIAL ROOTS-

1. WATER RETENTION - VELAMEN, A MULTIPLE EPIDERMIS, IS
        MECHANICAL PROTECTION AGAINST WATER LOSS.

2. PHOTOSYNTHESIS - SOME ORCHID ROOTS ARE PHOTOSYNTHETIC

3. SUPPORT - PROP ROOTS

ECONOMIC IMPORTANCE OF ROOTS

1. FOOD - CARROTS, BEETS (SUGAR AND RED), RADISHES

2. SPICES

3. DRUGS (IPECAC, GINSING, RESERPINE)

4. DYES (CARROTS, COFFEE)

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