BotanyBasics

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Transcript BotanyBasics

Botany Basics:
Evolution of Plants:

Land plants can be informally grouped based on
presence or absence of vascular tissue (cells
joined into tubes that transport water and nutrients
throughout the plant.)

A seed is an embryo packaged with a supply of
nutrients inside a protective coat. Seed plants can
be divided into two groups. Angiosperms and
Gymnosperms.
Angiosperms:
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Angion is from the Greek that means covered or
container, and sperm means seed.
Consists of all flowering plants.
Angiosperms seeds develop inside chambers
called ovaries.
Gymnosperms:
From the Greek gymno’s, “naked.”
 Seeds are not enclosed in chambers.
 Mostly conifers.

More Terms:

Some plants, including many garden
flowers, are called "annuals," which means
they complete their life cycle in one
growing season.They die when winter
comes, but their seeds remain, ready to
sprout again in the spring.

"Perennials" live for more than two years.
Monocots & Dicots
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Until the late 1990’s, most scientists divided
flowering plants (Angiosperms) into two groups,
based partly on the number of cotyledons, or seed
leaves.
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Monocots: One cotyledon.
Dicots: Two cotyledon’s.
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Other features help define the two groups
Monocot Leaf:
Dicot Leaf:
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Monocots:
– Lilies, grasses, cattails, palms, yuccas, orchids,
irises
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Dicots:
– Almost all kinds of trees and shrubs

Monocot Stem:
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Dicot Stem:
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Monocot Root
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Dicot Root
Vascular Tissues

Two types
1. Xylem
a) Conducts most of the water and minerals.
Includes tracheids (tube shaped cells). Are
dead cells that act like water pipes.
2. Phloem
b) This tissue includes living sugar-
conducting cells arranged into tubes that
distribute sugars, amino acids, and other
organic products.
Phloem
Transports sugars and
water throughout a
plant.
Transports under
pressure (like a straw)
Transports substances
in all directions
Parts of the Plant Body

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Leaves
Stems
Roots
Leaves:
The leaf is the main photosynthetic organ
of most vascular plants.
 Leaves vary in form but generally consist of
a flattened blade, and petiole, which joins
the leaf to a node of the stem.
 Grasses and many other monocots lack
petioles.

Leaves:
Simple vs. Compound Leaves:
Simple vs. Compound Leaves:

Simple leaves
are whole,
undivided leaves
growing from a
bud on the
stem. The node
is the part of the
stem where
leaves are
attached .

Compound: the
leaf consists of 3
or more leaflets,
each leaflet
being attached
to a leaf-stalk
(note: leaflets
are not attached
to a twig).
Opposite vs. Alternate:
Palmate vs. Pinnate:
Stomata
Stomata:
Stomata:
Stomata are microscopic pores found on
the under side of leaves.
 Stomata control the amount of carbon
dioxide that diffuses into a leaf and the
amount of water that evaporates from
leaves.
 The stomata is bounded by two half moon
shaped guard cells that function to vary the
width of the pore. Each guard cell contains
chloroplasts.

Stomata:
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In light the guard cells swell, causing the pore to be at its
widest, and CO2 diffuses into the leaf and into the cells to
be assimilated in photosynthesis.
In the dark or under drought conditions the guard cells are
not turgid, the stomata are closed and no photosynthesis
takes place.
The stomata is situated on the underside of the leaf for
the reason that if it were on the top side the plant would
lose to much water.
Because the guard cells are partially light activated, plants
under direct sunlight would constantly have their
stomata open and would thus lose much water and the
plant dying.
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a) Cuticle: Waxy layer water proofing upper
leaves.
b) Upper epidermis: Upper layer of cells. No
chloroplasts. Protection.
c) Palisade Mesophyll: Tightly packed upper
layer of chloroplast containing cells. Most
photosynthesis take place here.
d) Spongy Mesophyll: Lower layer of
chloroplast containing cells. Air spaces around
them.
e) Lower Epidermis: Lower external layer of
cells in leaf.
Fall leaves:
Why do leaves change color in the fall?
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Leaves are nature's food factories.
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Plants take water from the ground through their roots. They take a gas called
carbon dioxide from the air.
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Plants use sunlight to turn water and carbon dioxide into glucose. Glucose is
a kind of sugar.
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Plants use glucose as food for energy and as a building block for growing.
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The way plants turn water and carbon dioxide into sugar is called
photosynthesis.
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A chemical called chlorophyll helps make photosynthesis happen. Chlorophyll
is what gives plants their green color.
(Chlorophyll)

6CO2 +7H20+Light
C6H12O6 + O2+H2o
Why do leaves change color in the fall?
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Leaf color comes from pigments. Pigments are natural substances
produced by leaf cells. The three pigments that color leaves are:
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1)Chlorophyll
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2)Carotenoid
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3)Anthocyanins
Chlorophyll

1)Chlorophyll is the most important of the three. Without the chlorophyll in
leaves, trees wouldn't be able to use sunlight to produce food.
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All photosynthetic organisms have Chlorophyll A. This
is supplemented by Chlorophyll B and C, which are
accessory pigments.

Chlorophylls are bound to a protein, which makes it
insoluble in water. This is why its difficult to get out
grass stains from your clothes.
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During the summer, the leaves' chlorophyll molecules
absorb the other colors in the spectrum and reflect
green, so that is what your eye sees.
Carotenoid
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2)Carotenoid create bright yellows and oranges in familiar
fruits and vegetables. Corn, carrots, and bananas are just a few
of the many plants colored by carotenoid.
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Instead of capturing light for photosynthesis, carotenoids
protect the tree from the destructive power of chlorophyll.
(Electrons may combine with 02, then roam and destroy cells.
Anthocyanins
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3)Anthocyanins add the color red and blues to plants, including
cranberries, red apples, cherries, strawberries and others.
Least prevalent, but most colorful pigment.
Why do leaves change color in the fall?
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The color a leaf shows us in the fall is its "real"
color.
Why do leaves change color in the
fall?
During summer days, leaves make more
glucose than the plant needs for energy and
growth.
 The excess is turned into starch and stored
until needed. As the daylight gets shorter in
the autumn, plants begin to shut down their
food production.
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Evergreen trees -- pines, spruces, cedars and firs
-- don't lose their leaves, or needles, in winter. The
needles are covered with a heavy wax coating and
the fluids inside the cells contain substances that
resist freezing. Evergreen leaves can live for
several years before they fall and are replaced by
new growth.

Evergreens protect their needle-like foliage from
freezing with waxy coatings and natural
"antifreezes." But broadleaf plants, like sugar
maples, birches, and sumacs, have no such
protections. As a result, they shed their leaves.
Flower Anatomy:

Stamen - the male reproductive organ of a flower
– Anther - the part of the stamen that contains pollen; usually
borne on a stalk
– Filament This is the stalk of the Anther
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Carpel: The female reproductive organ of a flower.
– style - (botany) the narrow elongated part of the pistil between
the ovary and the stigma
– stigma - the apical end of the style where deposited pollen enters
the pistil
– ovary - the organ that bears the ovules of a flower
– ovule - a small body that contains the female germ cell of a
plant; develops into a seed after fertilization
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Sepal: A whorl of modified leaves in angiosperms. It
encloses and protects the flower bud before it opens.
Self-Fertilization
Reduces variability
 More common among plants in tropical
regions
 Plants prevent self-fertilization by placing
the stigma higher than the anther
- Ex. magnolia
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Pollination
 Pollination
is the transfer of pollen
from the anther to the stigma
 Fertilization is the union of the
sperm and egg
Plants Attract Their Vectors
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Attractants
– Nectar: birds and insects love this sweet taste
– Pollen: provides food for the busy bee
– Color: birds see red well, butterflies like bright
blues
– Scent: the smell of decayed meat will attract
flies and beetles
– Display: Can the flower support it’s pollinator?
Bats need large displays to rest on.
Vectors
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A vector is a means to
transfer the pollen
from one plant to
another.
Some vectors are
birds, beetles, flies,
bees, bats and
butterflies
The End