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PLANT DIVISIONS
Invasion of land
• Stomata
• Cuticle
• Lignin: bonds to cell wall
cellulose to add strength and
waterproofing
• Vascular tissue: xylem and
phloem
• Roots: absorb nutrients and
water vs. rhizoids of moss and
holdfasts of algae that don’t.
• Seeds: dormancy
• Fruit: spreading seeds
• Flowers: cross pollination
Cuticle
– A waxy cuticle covers parts exposed to air to prevent
dessication. Openings in the cuticle (stomata) allow for
gas exchange and are controlled by the guard cells.
Guard cells
Vascular tissue
– Most division (all
except bryophytes)
have vascular tissue of
xylem (water and
minerals) and phloem
(nutrients).
– Picture shows
vascular tissue in a
leaf in a bundle known
as a vein. These are
the lines you can see
in the leaf.
Carbon dioxide
• Plants lowered the levels of carbon dioxide from 25X
current levels to current levels over a period of 100 million
years as they adapted to and spread on land.
Cuticle, Dermal tissue, ground
tissue, and vascular tissue
Flagellated sperm vs. pollen
• The more primitive plants have flagellated sperm
that allow them to swim to the egg. This means
that the mosses, ferns, and other primitive plants
require water to have fertilization.
Fern sperm
Types of
pollen
Plant Divisions
• Divisions is used instead of phyla
Evolution of plants from green
algae
• A certain group of green algae known as the
charophytes have the following in common with plants.
– Chloroplasts of both have thylakoids stacked as grana and
chlorophyll b and carotene to act as accessory pigments for
chlorophyll a.
– The % of cellulose in both is around 25%
– Similar mitosis and cytokinesis mechanisms
– Similar sperm structure for sperm
– DNA evidence backs this up.
– Body of some charophytes is haploid, but fertilized egg is
retained in the organism and grows and then does meiosis:
clue to how alternation of generations started.
Plants
• NOTE: We use the
term Divisions
instead of the term
Phyla when referring
to plants.
• Characteristics of
plant kingdom
members
– Alternation of
generations with the
diploid sporophyte
generation dominant
except in bryophytes
Plant Divisions: Bryophyta
• MOSSES
• Dominant gametophtye
generation (green)
• Also includes liverworts and
hornworts
• Need sperm to fertilize egg
• NO vascular tissue limits
height of the plant and
therefore have no true roots,
stems, or leaves.
• haploid spores are made by
meiosis in the sporangium of
the sporophyte.
Moss
sporophyte
Other Bryophytes
Hornwort
Liverworts
• Homospory:
one type of
spore
• Heterospory:
female and
male spore.
Gametophytes
• Antheridium
• Male gametophyte
• Makes sperm
Archegonium
Female gametophyte
makes egg
Pterophyta: Ferns
• Homosporous: create one spore that is
bisexual.
• Vascular tissue but no seeds: allows them
to get taller, but limits them to shady moist
areas for reproduction.
• Fronds: big “leaf like” arrangement
• Fiddlehead: emerging sporophyte
• Sporangium make spores on underside of
fronds when reproducing.
Ferns
• Fiddlehead
• Sporangia on
underside of
frond
• Fronds
• Bisexual
gametophyte
Gymnosperms (naked seeds) have no
flowers: gingko, cycad, and conifers
Coniferophyta
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Redwoods, firs, pines, yews, cypresses
Naked seeds: not enclosed in fruits
Wind pollination (NEEDS A LOT)
Seeds, vascular tissue
No flowers
Often needles thick with cuticle and small
in size to limit transpiration.
Seed cones vs. pollen cones
Seed cones
seeds
Pollen cones
Oldest and largest
• Redwoods (400 feet tall)
bristlecone pine (4600 years old)
Anthophyta
• Flowering plants
• Flower will develop into fruit that is used for
seed dispersal via wind, water, or animal.
• Pollination can be by wind, bird, bat, insect.
• Most advanced (recent)
• Gametophyte is reduced and within the
flower.
• Most diverse: grasses to trees
Monocot (one cotyledon) vs. Dicot
(two cotyledons): the subdivisions
of anthophyta/angiosperms
Monocots
•Often grasses and the
relatives of grasses
Dicots
• Trees, garden plants
Vascular bundles location
Monocot: scattered
Dicot: ring around the outside
#2: veination in the leaves
• Parallel veins
• Monocot
Netlike veins
Dicot
#3: number of seed parts
#4:Flower parts
• Monocot
• Petals: in multiples of 3
Dicot
Petals: 4 or 5
Review Questions
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Which is haploid, spore or gamete?
Which is made by mitosis, spore or gamete?
Where is the vascular tissue of a monocot?
Are ferns homosporous or heterosporous?
Do bryophytes have roots?
Do ferns have pollen?
Do gymnosperms have seeds?
Where are fern sporangia found?
Flower structure: reproduction
organ of some plants
Parts: functions
• Female (carpel/pistil)
– Stigma is sticky “top” that collects pollen
– Style is connection between stigma and ovary.
– Ovary is where eggs are made in the ovules
• Male (stamen)
– Anther makes the pollen
– Filament holds anther away from female part to allow for
wind/insect to carry pollen away
• Petals (collectively called corona): attracts
pollinators
• Sepals (collectively called calyx); protects the bud
before blooming
Monoecious (one house) plant: has
both male and female on one plant
• Name the parts
• Dioecious: Two
houses/ male
and female
plant
• Complete: one
flower had both
female and
male while
incomplete has
only one
Prefixes for plants
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Mega and Arche are female
Micro and Anther are male
Microgametophyte = pollen (becomes sperm)
Megagametophyte = makes eggs
Atheridium: anthers make male gametes
Archegonium: place where eggs are made
Double Fertilization
• Generative nucleus becomes two “sperm” through
mitosis. First sperm fertilizes egg in the ovule and
second sperm fertilizes polar nuclei to become triploid
endosperm. Endosperm will become “food” for seed.
Seed and Fruit
• Seed, Develops from the ovules within the
ovaries: Covering (seed coat), food
(endosperm), embryo
– Allows for dormancy until conditions are right
– Germination triggers massive cell division and
cellular respiration
• Fruit: The ripened ovary becomes the fruit
after fertilization leading to making of the
seeds: seed dispersal is the goal
• Vegetable: part of a plant you eat: not a
biological term
Fruit: Seed
dispersal
Review
• The helicopters of a maple tree are what part of the
plant?
• What is made by the archegonium?
• What part of the flower “catches the pollen?
• What is one gymnosperm other than
coniferophyta?
• What part of a flower becomes the fruit?
• What part of the flower becomes the seed?
• What are the two products of double fertilization?
More review
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How do pine trees get pollen to the female?
How do apple trees get pollen to the female?
What division of plants includes the tallest trees?
What is the food of a seed called?
What is the purpose of the endosperm?
What group of green algae are the closest relatives to
plants?
• What does the cuticle prevent?
• What division of plant has no flowers, but does have
seeds?
• What is true of plants that are heterosporous?