PLANT SCIENCE:
Botany
Plant Importance
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Primary food source
Produce oxygen
Cooling
Renew air
Slow wind
Prevent erosion
Provide shelter
Beautify
Building materials and fuels
Parts of Plants
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Four basic parts: leaves, stems, roots, and flowers
 Flowers

later become fruits or seeds
Leaves:
 Food
factory location (photosynthesis)
 Shape
 Used
and size vary
for identification of plants
 Arrangement
varies
Leaf Arrangement
External Leaf Structure
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Petiole – leaf stalk
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Blade – larger, usually flat part of leaf
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Veins – form structural framework
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Midrib – large, central vein that all other veins extend from
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Margins – edges of leaves
External Leaf
Leaf
Structures
Internal Leaf Structure
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Cuticle – waxy covering layer
Epidermis:
 “skin”
of leaves
 Single layer of cells
 Prevent moisture loss
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Guard cells:
 Open
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and close pores on the underside of the leaf
Stoma:
 Pores
 Allow
transpiration (exchange oxygen and carbon dioxide)
Leaf Structures
Internal Leaf
Internal Leaf Structure
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Chloroplasts:
 Green
due to chlorophyll (pigment)
 Manufacture food through photosynthesis
A
process where carbon dioxide and water in the presence of
light are converted into sugar and oxygen
 6CO2 + 6H2O + light energy  C6H12O6 + 6O2
Respiration
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Consume oxygen and give off carbon dioxide
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All plants need oxygen to all parts (including roots!)
 If
not, can lead to death
 Poor

drainage, over watering
Plants produce more oxygen than they consume
Stems
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Functions:
 Movement
of materials
 Water
and minerals up from roots
 Food down to roots
 Support
of the leaves and reproductive structures
 Flowers,
 Food
 If
fruits, seeds
storage and/or production
green, can use photosynthesis
 Reproduction:
 Cuttings
and rafting
Stems: external structure
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Lenticels – breathing pores
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Bud scale scars – where a terminal bud has been located
 Distance
between 2 scars = one year of growth
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Leaf scars – where leaves were attached
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Terminal bud – a bud at the end of the stem
 Produces
new growth
Stem Structure
Stems: internal structure
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Xylem – carries water and minerals UP
Phloem – carries manufactured food DOWN
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Dicots:
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Plants that have 2 seed leaves (cotyledons)
Xylem and phloem from 2 layers separated by cambium
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Produces all new cells (phloem to outside, xylem to inside)
ie: trees
Continues to grow as long as it lives, not limited in size
Monocots
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1 seed leaf
ie: corn
Vascular bundles: phloem and xylem tissue in a bundle
All cells are formed in initial growth, cells simply expand over time
Limited in size
Monocot Stem
Dicot Stem
Monocot versus Dicot
Roots
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Underground, not visible (usually)
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Functions:
 Anchor
 Absorb
 Store
water and minerals
food
 Reproduce
(some plants)
Root Internal Structure
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Outer phloem (corklike bark)
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Cambium
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Xylem
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Very similar to stem internal structure
Root External Structure
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Root cap
 Produces
 Helps
a continuous supply of new cells
to push a path through soil
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Primary root
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Lateral roots
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Root hairs
 Absorb
water and minerals
Root Structures
Root Systems: Fibrous Roots
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Much easier to transplant
Roots are shorter, smaller and more compact
Root Systems: Tap Roots
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Longer with fewer roots
Root Systems: Comparison
Flowers: types
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Vary in size, shape, and color
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Complete flower: has both male and female parts
 Self-fruitful
 Can
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pollinate itself
Incomplete flower: has only male OR female parts
Complete Flower Parts
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Sepal: green, leaf-like part that covers and protects the
flower bud before it opens
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Petals: modified leaves used to attract pollinators
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Pollinators: insects, birds, animals, wind, etc
 Used
to fertilize plants to produce seeds
Complete Flower Parts
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Stamens: male reproductive organs
Stalk- filament
 Anther- sac-like structure at top of filament
 Pollen- male sex cells, contained in anther
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Pistil: female reproductive organs
Center of flower
 Produces eggs- when fertilized by pollen, become seeds
 Stigma: sticky top region, used to catch pollen
 Style: tube leading from stigma to ovary to transport pollen
 Ovary: where the egg cells develop and are fertilized
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After fertilization, ovary becomes a fruit or seed coat
Complete Flower
Incomplete Flowers: Differences
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Does not have both male and female parts
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Male: sepals, petals, and stamen
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Female: sepals, petals, and pistil
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Pollinated by same factors, but must move between
flowers, not within flower
Incomplete Flower
The Role of Flowers
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Beauty
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Reproduction
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Economic value
 Multimillion
dollar business