Units 22 and 23
•SEED PLANTS
Life Llife Cylce of
Nonseed Plant Life Cycle
Seed Plant Life Cycle
Flagellated sperm must swim
Pollination
How Did Seed Plants Become Today’s Dominant
How Did Seed Plants
• Late in the Devonian, some
Vegetation?
Become Today’s
plants developed
secondary growth:
Dominant Vegetation?
• Thickened woody stems of
xylem
• Which led to:
• Stems
• Leaves
• Roots
• Flowers
Seed plants fall
into two groups:
• Gymnosperms: pines and cycads
• Angiosperms: flowering plants
SEESEEDS
Let’s look at……….
•What separates
Seed plants from
Seedless plants?
• The SEED provides the
embryonic plant essential
nourishment and
protection.
• The SEED it's self has
stored nutrients allowing
it to stay dormant until
conditions are just right
for germination to begin.
• Seed Plants
• Evolution of the seed
has changed the
destiny of plants
• Give plants a "head
start"
• Provide food for
humans and animals
Three vegetative organs of a generalized plant
Leaves
Stem
Roots
Roots…..
Anchor the plant in soil
Absorb water and minerals
from soil
Stores products of
photosynthesis
Stems…..
supports a leaf, flower, or fruit
the main body of a plant which is
above ground; trunk; stalk.
Leaves…..
The organ that produces food
for the plant –photosynthesis
Well adapted for gathering
light
Leaf Anatomy
Cuticle
Stoma
Guard cells
Parenchyma
Collenchyma
Vascular tissue:
Vein
Xylem
Phloem
Leaf Diversity
Leaf diversity for us
• A simple leaf has a single
blade.
• A compound leaf has
multiple blades (or
leaflets) arranged along
an axis or radiating from a
central point.
Monocot vs. Dicot leaf
Dicot Leaf
Monocot Leaf
Gymnosperms
• Any vascular plant that
reproduces by means of an
exposed seed, or ovule
• “Naked Seed”
• Mature on the
surface of a cone
• The nutritive
material
accumulates prior
to fertilization
Angiosperms
• Flowering plants are the
dominant plant today
• They are the largest group of plants
with about 90% of all plant species.
.
A
•Angiosperm
 Protected Seeds
 In angiosperms the
nutrient materiel is
stored only after
fertilization.
 Seeds are encased in
a fruit
 Fruits are the product
of flowers
A
• Angiosperm -Protected Seeds
 Dry fruit vs. Fleshy fruit
• FLOWERS are the
exclusive reproductive
organ of angiosperms
• “The earth laughs
in flowers
” Ralph Waldo Emerson
Angiosperm: “enclosed seed”
• Male reproductive structures
Stamen



Female reproductive structures
Carpel
Stigma, style, and ovary
bear megasporangia -egg
(one or more carpel make up a pistil)
Anther
Filament
bear microsporangia - sperm ( pollen)
• Pollen
•
B
- Dandelion (Taraxacum sp.) Transmission electron microscopy
•
F
- Pine (Pinus sylvestis): Light microscopy
•
G
- Mixed pollen grains (bright field light microscopy, stained)
• Flowers may have
contributed to the
enormous success
of angiosperms.
• The flowers attract
a pollinators which
carry pollen to
other individuals of
the same species
Attracted to sweet smells
Need landing platform
Attracted to strong smells
Can hover; nocturnal
Need bigger landing platform
Like bright colors
Can hover
Prefer red color
•
Double fertilization
Sperm A leads to the
formation of a Seed
Sperm B leads to the
formation of an endosperm
(a nutritive tissue within the
seed that feeds the
developing plant embryo)
•Cotyledon
• Embryonic seed
• is the first leaf or
set of leaves that
sprout from a
seed
• Store nutrients
for the embryo
• A cotyledon – “seed leaf”
• contain nutrients for growth during embryonic
development
• upon germination, the cotyledon may become the
embryonic first leaves of a seedling
• Flowering plants are divided into two groups
Final thoughts…………..