Plant Diversity
Chapter 22
22-1 Introduction to Plants

Plants are the base for the food chain on land.

Provide shade, shelter, food and oxygen

Evolved more than 470 million years ago

Trees, shrubs, grasses, mosses and ferns
22-1 Introduction to Plants
yoo-KAR-ee-ah-tik
What is a Plant?


Multicellular – more than 1 cell
Eukaryotic – cells have a nucleus

Cell walls made of cellulose

Photosynthesis using chlorophyll a and b
22-1 Introduction to Plants
The Plant Life Cycle
Plant
life cycles have two
alternating phases, a diploid (2N)
phase and a haploid (N) phase,
known as alternation of generations.
22-1 Introduction to Plants
guh-MEET-uh-fyt
The Plant Life Cycle

Haploid (N)-Gametophyte
Gamate (sex cell) Producing
 Sex cells produced during meiosis


Diploid (2N)-Sporophyte
Spore Producing
 Produce a new individual by mitosis

22-1 Introduction to Plants
SPOH-ruh-fyts
Alternation of Generations
Two multi-cellular body forms:
Gametophyte (haploid) that produces
gametes. Gametes fuse to form zygotes that
develop into…
Sporophytes (diploid) that produce
spores. Spores are haploid cells that can
develop into a new organism.
22-1 Introduction to Plants
Alternation of
Generations
22-1 Introduction to Plants
What Plants Need to Survive

Sunlight


Water and Minerals


Water for photosynthesis, minerals for growth
Gas Exchange



Energy to carry out photosynthesis
CO2 for photosynthesis
O2 for respiration
Movement of Water/Nutrients


Make food in their leaves – moves down
Water and nutrients – moves up
22-1 Introduction to Plants
Early Plants

First plants were dependent on water

Evolved from multicellular green algae

Similar to today’s mosses in structure and
grew close to the ground

Evolved different adaptations for terrestrial
(land) environments
22-1 Introduction to Plants
kuhk-SOH-nee-uh
The First Plants

The first true plants
were dependent on
water to complete
their life cycles,
similar to today’s
mosses in that they
were simple in
structure and grew
close to the ground.
Cooksonia, a vascular plant 400 million years old
22-1 Introduction to Plants
Overview of the Plant Kingdom
 Plants
are divided into four groups based on
these features:
 water-conducting tissues
 seeds
 Flowers
 Plants
are also classified by other features,
including reproductive structures and body plan.
22-1 Introduction to Plants
Overview of the Plant Kingdom
Four Main Groups of Land Plants
•Bryophytes – mosses and their relatives
•Pterophytes – ferns and their relatives
•Gymnosperms – (naked seeds) cone bearing
•Angiosperms – flowering plants
22-1 Introduction to Plants
Cladogram of Plant Groups
Section 22-1
Flowering
Plants
Cone-bearing
plants
Ferns and
their relatives
Mosses
and their
relatives
Flowers;
Seeds
Enclosed
in Fruit
Seeds
Green
Algae
Ancestors
Water-Conducting
(Vascular) Tissue
(shows evolutionary relationships)
22-1 Introduction to Plants
Bryophytes: Moss
BRY-oh-fyts
22-1 Introduction to Plants
Pterophytes: Ferns
TERH-oh-fyts
22-1 Introduction to Plants
JIM-noh-spurmz
Gymnosperms: Cone Bearing
22-1 Introduction to Plants
AN-jee-oh-spurmz
Angiosperms: Flowering plant
22-1 Introduction to Plants
Some highlights
of plant evolution
22-1 Introduction to Plants
The Diversity of Plants
Cone-bearing plants
760 species
Ferns and
their relatives
11,000 species
Mosses and
their relatives
15,600 species
Flowering
plants
235,000 species
BRY-oh-fyts
22-2 Bryophytes

Nonvascular plants

Use osmosis to draw up water

Water needed for reproduction

Act as natural sponge and form peat moss

Include moss, liverworts and hornworts
22-2 Bryophytes
BRY-oh-fyts
Groups of Bryophytes

Moss

Liverworts

Hornworts
22-2 Bryophytes
BRY-oh-fyts
22-2 Bryophytes
bri-oh-FYT-uh
Moss (Phylum Bryophyta)
22-2 Bryophytes
hih-PAT-ik-oh-fy-tuh
Liverwort (Phylum Hepaticophyta)
Can reproduce
asexually.
Gemmae can
divide by mitosis
JEM-ee
“Hepatic”
because it is
“liver” shaped
22-2 Bryophytes
An-tho-SEHR-oh-fy-tuh
Hornwort (Phylum Athocerophyta)
22-2 Bryophytes
Asexual
Reproductive
Structure
The
Structure
of a moss
plant
Diploid (2N)
(spores)
Sexual
Reproductive/
Photosynthetic
Structure
Haploid (N)
(sperm & egg)
22-2 Bryophytes
BRY-oh-fyts
Life Cycle of Bryophytes

During at least one stage of their life
cycle, bryophytes produce sperm that
must swim through water to reach eggs
of other individuals.

Therefore, they must live in places
where there is rainfall or dew for at
least part of the year
22-2 Bryophytes
The life cycle of
Polytrichum,
a moss
poly-TRY-cum
22-2 Bryophytes
The life cycle of
Polytrichum,
a moss
poly-TRY-cum
22-2 Bryophytes
The life cycle of
Polytrichum,
a moss
poly-TRY-cum
22-2 Bryophytes
arc-uh-GOH-nee-um
Life Cycle of Bryophytes (moss)
Gametophytes
Capsule
Archegonia
Sporophytes
Protonema
22-2 Bryophytes
SFAG-num
Human Uses of Mosses
1. Bryophytes were world’s only plants for 100 million years.
2. Peat bogs are made mostly of moss called
sphagnum. They contain 400 billion tons of carbon and cut
down the amount of greenhouse gases. Peat is harvested,
dried, and used as a fuel.
3. Sphagnum is harvested for use as a soil conditioner and
plant packing material.
22-2 Bryophytes
SFAG-num
Sphagnum, or peat moss
22-3 Seedless Vascular Plants
 In
just a few million years, plants grew
taller and taller on the landscape.
Q: What caused this increase in size?
A: Vascular Tissue
22-3 Seedless Vascular Plants
Evolution of Vascular Tissue
 Specialized
tissue (groups of cells)
that conduct water and nutrients
through plant even against gravity.
22-3 Seedless Vascular Plants
TRAY-kee-id
Evolution of Vascular Tissue
Tracheid Cells
 Hollow
cells with thick cell walls that
resist pressure
 They
connect end to end to allow
water to move efficiently.
22-3 Seedless Vascular Plants
ZY-lum
Evolution of Vascular Tissue
Xylem Cells
 Carry
water
 Upward
from the roots to every part of
the plant
22-3 Seedless Vascular Plants
FLOH-um
Evolution of Vascular Tissue
Phloem Cells
 Transport
nutrients and carbohydrates
produced by photosynthesis
 From
the leaves down to the roots
22-3 Seedless Vascular Plants
Evolution of Vascular Tissue
22-3 Seedless Vascular Plants
Evolution of Vascular Tissue
 Vascular
plants also evolved the ability
to produce lignin, a substance that
makes cell walls rigid.
 The
presence of lignin allows vascular
plants to grow upright and tall
22-3 Seedless Vascular Plants
Ferns and Their Relatives
 Seedless
vascular plants include club
moss, horsetails, and ferns.
 Like other vascular plants, ferns and
their relatives have true roots, leaves,
and stems.
22-3 Seedless Vascular Plants
Roots
 Absorb
water
and minerals
22-3 Seedless Vascular Plants
Leaves
 Collect
light for photosynthesis
22-3 Seedless Vascular Plants
Veins
 Made
of xylem and phloem
22-3 Seedless Vascular Plants
Stems
 Used
for
support,
connect roots
and leaves,
carry water &
minerals
22-3 Seedless Vascular Plants
LY-ko-fy-tah
Club Moss (Phylum Lycophyta)
22-3 Seedless Vascular Plants
AHR-thro-fy-tah
Horse Tail (Phylum Arthrophyta)
Just
Kidding!
22-3 Seedless Vascular Plants
AHR-thro-fy-tah
Horse Tail (Phylum Arthrophyta)
22-3 Seedless Vascular Plants
Ferns and Their Relatives

Club Moss

Horse Tails
22-3 Seedless Vascular Plants
TERH-oh-fy-tah
Fern (Phylum Pterodphyta)
Ferns have
vascular tissues,
strong roots,
underground
stems called
rhizomes,
and leaves
called fronds.
22-3 Seedless Vascular Plants
Life Cycle of Ferns
•Sporophyte is dominant stage
bryophytes have dominant gametophyte
•Alternation of generations
•Ferns are dispersed to new environments as
spores; no seeds present
22-3 Seedless Vascular Plants
22-3 Seedless Vascular Plants
Spoh-RAN-jee-uh
Life Cycle of Ferns
 Fern
sporophytes develop haploid
spores on the underside of their
fronds in structures called sporangia.
 Sporangia
called sori.
are grouped into clusters
22-3 Seedless Vascular Plants
Spoh-RAN-jee-uh
Life Cycle of Ferns
 The
Underside of a Fern Frond
Sporangia
Sorus
22-3 Seedless Vascular Plants
Life Cycle of Ferns
Sori
SOH-ry
22-3 Seedless Vascular Plants
SOHR-uhs
Life Cycle of Ferns
Sorus
22-3 Seedless Vascular Plants
Spoh-RAN-jee-um-
Life Cycle of Ferns
Sporangium
Releasing
Spores
22-3 Seedless Vascular Plants
A fern spore
Life Cycle of Ferns
Spore
22-3 Seedless Vascular Plants
Life Cycle of Ferns
Young
Gametophyte
guh-MEET-uh-fyt
22-3 Seedless Vascular Plants
22-3 Seedless Vascular Plants
arc-uh-GOH-nee-uh
Life Cycle of Ferns
 The
antheridia and archegonia are
found on the gametophyte.
 In
ferns, fertilization requires water,
which allows the sperm to swim to
the eggs.
22-3 Seedless Vascular Plants
guh-MEET-uh-fyts
Life Cycle of Ferns
Archegonia
Contain
Eggs
Antheridia
Contain
Sperm
Mature
Gametophytes
22-3 Seedless Vascular Plants
arc-uh-GOH-nee-uh
Life Cycle of Ferns
Archegonia
Contain Eggs
22-3 Seedless Vascular Plants
Life Cycle of Ferns
Developing
Sporophyte
SPOH-ruh-fyt
22-3 Seedless Vascular Plants
Life Cycle of Ferns
22-3 Seedless Vascular Plants
Life Cycle of Ferns
22-4 Seed Plants
22-4 Seed Plants
Seed plants are the
most dominant group
of photosynthetic
organisms on land.
22-4 Seed Plants
Seed plants are divided into two groups:
Gymnosperms
bear seeds directly on
the surfaces of cones.
Angiosperms,
or flowering plants, bear
seeds within a layer of tissue that
protects the seed.
22-4 Seed Plants
Gymnosperms include conifers,
cycads, ginkgoes and gnetophytes.
22-4 Seed Plants
Angiosperms include grasses, flowering
trees, shrubs, and all species of flowers.
22-4 Seed Plants
Reproduction without Water

Unlike mosses and ferns, seed plants do
not require water for fertilization of gametes.
Q: Why was this an advantage?
A: They can live further away from water
22-4 Seed Plants
Reproduction without Water
Adaptations that allow seed plants to
reproduce without water include:
flowers or cones
the transfer of sperm by pollination
the protection of embryos in seeds
22-4 Seed Plants
Reproduction without Water

Cones - seed bearing structure for gymnosperms

Flowers - seed bearing structure of angiosperms

Pollen grains - contain male gametophytes

Seeds - embryo with seed coat and food supply

Eaten and dispersed by animals or stick to fur

Fossils from 30 million years ago
22-4 Seed Plants
Cones
 Seed
bearing structure of gymnosperms
22-4 Seed Plants
Flowers
 Seed
bearing
structures of
angiosperms
22-4 Seed Plants
Pollen grain
 Contains
male
gamete
(sperm)
22-4 Seed Plants
Pollination
 Transfer
of pollen from the male
gametophyte to female gametophyte
22-4 Seed Plants
A Bee With Pollen On It’s Leg
22-4 Seed Plants
Seeds
22-4 Seed Plants
Seed
 Embryo
of plant
 Encased
in a
protective coat
 Surrounded
by
a food supply
22-4 Seed Plants
Embryo
 Early
development
stage of plant
 Seed’s
food supply
provides nutrients
as embryo grows
22-4 Seed Plants
Seed Dispersal
22-4 Seed Plants
Evolution of Seeds Plants

Over a period of millions of years, continents
became much drier, making it harder for
seedless plants to survive and reproduce.

For that reason, many moss and fern species
became extinct. They were replaced by seed
plants with adaptations that equipped them to
deal with drier conditions.
22-4 Seed Plants
Gynosperms – Cone Bearers
 Cone
plants - oldest seed plants
 Bear
their seeds directly on the
surfaces of cones
Ex.) conifers, cycads, ginkgoes and
gnetophytes
22-4 Seed Plants
Gymnosperms include conifers,
cycads, ginkgoes and gnetophytes.
22-4 Seed Plants
Gymnosperms
 Contains
the
oldest living
plant – Bristle
cone pine
 Contains the
tallest living
plant – Sequoia
or redwood
22-4 Seed Plants
NEE-toh-fyts
Gynosperms – Cone Bearers
1)
Gnetophytes - (gnetophyta):


Ex. Welwitschia-Namibian desert with large,
leathery leaves; spread across the ground
Cycads - (Cycadophyta):



Palm-link plants with large cones
Appeared during Triassic Period (225 million yrs ago)
Grow in tropical and subtropical places
22-4 Seed Plants
Gynosperms – Cone Bearers
3)
Ginkgoes - Only Ginkgo biloba currently exists



4)
One of the oldest seed plant species alive today
Cultivated in China and planted around temples
Often planted in urban settings in U.S. due to
resistance to air pollution
Conifers - (Coniferophyta)



Ex. Pines, spruces, firs, cedars, sequoias, redwoods
Long, thin leaves (Ex. Pine needles)-reduces surface
area, waxy layer
Most are “evergreens” with cycling of needles
22-4 Seed Plants
NEE-toh-fy-tuh
Gnetophytes (Phylum Gnetophyta)
Welwitschia mirabilis
22-4 Seed Plants
SY-kad-oh-fy-tuh
Cycads (Phylum Cycadophyta)
22-4 Seed Plants
GING-koh-fy-tuh
Ginkgoes (Phylum Ginkgophyta)
22-4 Seed Plants
Koh-nif-ur-oh-FYT-uh
Conifers (Phylum Coniferophyta)
22-5 Angiosperms – Flowering Plants
 Phylum

Anthophyta “enclosed seed”
Flowering plants
 Bear
their seeds within a layer of
tissue that protects the seed (fruit)
Ex.) grasses, flowering trees shrubs, all
species of flowers
22-5 Angiosperms – Flowering Plants
Angiosperms include grasses, flowering
trees, shrubs, and all species of flowers.
22-5 Angiosperms – Flowering Plants
Flowers and Fruits

Angiosperms have unique reproductive
organs known as flowers.
Q: Why are flowers great evolutionary
adaptations?
A: They attract animals that pollinate them
22-5 Angiosperms – Flowering Plants
Flowers and Fruits

Flowering plants
originated on land
and quickly came to
dominate Earth’s
plant life.

The vast majority of
living plant species
reproduce with
flowers.
22-5 Angiosperms – Flowering Plants
22-5 Angiosperms – Flowering Plants
Flowers and Fruits
 Flowers
contain ovaries, which
surround and protect the seeds
 After
pollination, the ovary develops
into a fruit, which protects the seed
and aids in its dispersal.
22-5 Angiosperms – Flowering Plants
Fruit
 Ripened
ovary
 thick
wall
of tissue

surrounds
the seed
22-5 Angiosperms – Flowering Plants
Diversity of Angiosperms
 The
angiosperms are an incredibly
diverse group. There are many ways
of categorizing these plants.
 Monocot
vs. Dicot
 Woody vs. Herbaceous
 Annual vs. Biennial vs. Perennial
22-5 Angiosperms – Flowering Plants
Monocots vs. Dicots
 Cotyledons
– “seed leafs” in the embryo.
Monocots have
one seed leaf
Dicots have
two seed leafs
22-5 Angiosperms – Flowering Plants
Monocots vs. Dicots
Monocots
Dicots
Seeds
Single
cotyledon
Two
cotyledons
Leaves
Parallel
veins
Branched
veins
Flowers
Floral parts
often in
multiples of 3
Floral parts often
in multiples
of 4 or 5
Stems
Vascular
bundles
scattered
throughout stem
Vascular
bundles
arranged in
a ring
Roots
Fibrous roots
Taproot
22-5 Angiosperms – Flowering Plants
Woody vs. Herbaceous
plants – have woody stems
 trees, shrubs, vines
 Woody
22-5 Angiosperms – Flowering Plants
Woody vs. Herbaceous
 Herbaceous
stems are smooth and
nonwoody
dandelions,
tomatoes, and
sunflowers
22-5 Angiosperms – Flowering Plants
Annuals, Biennials & Perennials

Annuals - Complete a life-cycle within one
growing season
Ex. Marigolds,
petunias, pansies,
zinnias, wheat and
cucumbers
22-5 Angiosperms – Flowering Plants
Annuals, Biennials & Perennials

Biennials - Complete life cycle in 2 years
 Year 1- germinate and grow roots &
very short stems
 Year 2 - Grow new stems and leaves
and produce flowers and seeds
Ex. Carrots,
primrose, parsley,
celery
22-5 Angiosperms – Flowering Plants
Annuals, Biennials & Perennials

Perennials - Live for more than 2 years
Ex. Asparagus, grasses - herbaceous
Ex. Maple trees-woody stem
Chapter 22 Review
1. Bryophytes – liverworts, hornworts, mosses
- Bryophytes have no vascular tissues.
- Bryophytes live in damp/moist environments and are small
so they don’t need vascular tissue. They are sometimes called
non-vascular plants.
-Gametophyte is the dominant recognizable stage in the life
cycle of bryophytes (does most of the plant’s photosynthesis)
- The rest three groups are all vascular plants.
- Vascular plants have cells that are joined to produce
tubes that transport water and nutrients throughout the
plant. Vascular plants do not rely on water for reproduction
Chapter 22 Review
The vascular plants are, in order of their evolution:
2. Pteridophytes – ferns, horsetails, lycophytes
a. seedless plants
3. Gymnosperms – conifers, ginkgo, cycads, gnetopsids
a. early seed plants
b. produce naked seeds
4. Angiosperms – flowering plants
a. seeds protected by growing in ovaries
b. majority of modern plants are in this group
Sporophyte is the dominant recognizable stage in the life
cycle of Vascular (do most of the plant’s photosynthesis