Transcript Root, Stem, and Leaf Lecture

Roots, Stems, Leaves, & Flowers
Notes
I. Roots
Roots
A. Functions
• Absorb water and minerals.
• Transport water up to the stem.
• Store water and food.
• Anchor.
B. Parts
1. Xylem
• X shaped
• center of the root
= vascular tissue
that transports
water up to the stems.
2. Phloem
=vascular tissue that transports food down
from the leaves and stems.
• Roots have 4 bundles of phloem found in
the “corners” of the xylem.
3. Cambium
= Growth tissue that produces new xylem and
phloem.
• Found between the xylem and phloem.
4. Cortex
• outside ring.
• Stores food and water.
5. Root Hairs
= single-celled extensions on the root whose
purpose is absorbing water.
6. Root tips
• Cap = hard tip that pushes through soil.
• Apical Meristem
Meristem = Plant growth tissue.
C. two types of root systems
1. Taproot system
• composed of a few
large roots
examples: carrot,
tree.
2. Fibrous root system
• composed of a mat of
tiny roots.
Example: grass
D. Mycorrhiza
= mutualism
= fungus and plant roots
E. Adventitious roots
= roots that arise from some place other than
the primary root.
F. Perennial roots
= root system that survives from year-to-year
as top of the plant is annually dormant.
G. Root Foods
• Carrots
• Radishes
II. Stems
A. Functions
• Transport materials between roots and
leaves.
• Support leaves and flowers.
B. Parts
• Xylem
• Phloem
• Cambium/Meristem
herbaceous
= a plant that is soft, green, and has a thin
bark.
C. Types of Stems
1. Herbaceous monocot stem
• vascular bundles are scattered.
2. Herbaceous dicot stem
• vascular bundles form a circle.
3. Woody stem
• contains wood
• brown
• tough
• thick bark
http://www.mhhe.com/biosci/pae/botany/histology/html/woodsmic.htm
D. Food Stems
1. Potatoes are
called tubers.
• Swollen tip
of an underground
stem.
2. Onions are called bulbs.
• Small stem surrounded by thick, juicy
leaves.
3. Celery is a stem.
III. Leaves
1. Function
• Photosynthesis!
• Transport Food
• Store Food
2. Parts
A. Cuticle
=waxy, waterproof covering.
– Not made of cells.
B. Upper Epidermis
– like skin.
– made of cells.
C. Lower Epidermis
– Stomata
= holes that let CO2 in and H2O out.
– Guard Cells
= cells that surround the stomata.
– Transpiration
= plants release water from stomata.
D. Palisade Layer
– long, tall cells found under the upper epidermis.
– Lots of chloroplasts!
– Most photosynthesis occurs here!
E. Spongy Layer
– Loose cells with lots of air space.
F. Veins
• Xylem
– Bring water into the leaf.
– Top of the vein.
• Phloem
– Takes sugar from the leaf.
– Bottom of the vein.
3. Turgor
=pressure of water inside a plant cell
– Causes the cell membrane to press against the
cell wall.
– Causes the cell to be stiff.
– High Turgor causes the leaf to be
rigid.
– Low Turgor causes the leaf to be
wilted.
IV. Flowers
A. Function of Flowers
• Flowers are for sexual reproduction.
• Flowers produce seeds and fruit.
B. Parts of a Flower
1. Pistil
= female reproductive structure.
The Pistil contains three main parts:
a. Stigma
= top of the pistil where
the pollen sticks.
b. Style
= stalk
c. Ovary
=bottom of the pistil.
=produces ovules
– Ovules are the female gametophytes.
2. Stamen
= male reproductive structure
• Produces pollen
• Pollen is the male gametophyte
• 2 parts
(1) Filament
= stalk
(1) Anther
= pollen
producing
sac
3. Petals
• Modified leaves
• Often Colorful
• Often attracts pollinators
• Often produces
nectar
• Protect the
developing
reproductive
organs
4. Sepals
• Modified leaves
• Often green
• Protect the un-opened flower
C. Pollination
= the transfer of the pollen from an anther to a
stigma.
• Birds
• Bees
• Wind
D. Fertilization
= Fusing of the male and female gamete.
• Flowers undergo double fertilization
• The results are the zygote
and the endosperm.
E. Fruit
= ripened ovary
= if it contains seeds in an ovary wall, it is a
fruit.
F. Seed Dispersal
• Tasty fruits and seeds are eaten and
deposited in a nice pile of “fertilizer”
• Stickery fruits hang on to fur and britches
• Aerodynamic fruits are blown
• Floaty fruits disperse by water