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Roots, Stems, Leaves, & Flowers Notes
I. Roots
RootsA. Functions
• Absorb water and minerals.
• Transport water up to the stem.
• Store water and food.
• Anchor.
B. Parts1. 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 systems1. 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 barkhttp://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. PartsA. 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 Flower1. Pistil
= female reproductive structure.
The Pistil contains three main parts:a. Stigma= top of the pistil where
the pollen sticks.b. Style= stalkc. 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