Pl t E l ti & Di itPlant Evolution & Diversity · First tracheophytes Phylum Rhyniophyta Had the basic structures observed in all other tracheophyte phyla Club mosses (Lycophyta)

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Pl t E l ti & Di itPlant Evolution & Diversity

AP Biology Rapid Learning Series

Rapid Learning Centerwww.RapidLearningCenter.com/© Rapid Learning Inc. All rights reserved.

AP Biology Rapid Learning SeriesWayne Huang, PhD

Andrew Graham, PhDElizabeth James, PhD

Casandra Rauser, PhD Jessica Habashi, PhD

Sara Olson, PhDJessica Barnes, PhD



Learning ObjectivesBy completing this tutorial, you will learn about:

Plant EvolutionOrdovician Period 488 Million Year Ago

Plant Diversity

Plant Classification

Plant Adaptations

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Oldest Land Plant Fossils

Concept Map: Evolution and DiversityEvolution Origin of plants from algaeOrigin of plants from algae

-500 x 106 yearsEvolved from algae

300,000 types of plants

Photosynthetic EukaryotesPhotosynthetic Eukaryotes Roots, cuticleRoots, cuticlestomata etc

MulticellularCell wall of cellulose

chlorophyllEmbryophytesEmbryophytes

Land plants

Tracheids Vs Non TracheidsTracheids Vs Non Tracheids

Land Adaptation

Divided into 10 phyla

Cell type

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No realroots

Seed bearingSeed bearingSeedless

Protect embryoProtect embryo

Definition

Tracheids

Bryophytes



Plant Evolution

IntroductionEvolution

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EvolutionFossil RecordsAncestral Origin Invasion of LandAdaptation to Land

Plants are photosynthetic

multicellular eukaryotes.

Embryophytes are a group of plants made up of bryophytes and vascular plants: trees, flowers ferns mosses and other

Plant Introduction and Overview

eukaryotes. flowers, ferns mosses and other green land plants.

Embrophytes produce an embryo that is protected by tissues of the

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tissues of the parent plant.



Evolution of Plants

Fossil evidence indicates plants are derived from green algae between 400-500 million years ago when some algae moved on land.

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cyanobacteria aka blue-green algae3 Billion years ago

Age of Plants

350 MYAVascular plants appeared

300 MYAForests

d.

500 MYA 360 MYA

appeared appeared

150 MYA

Mosses

Ferns Cycads

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500 MYALand plants from green algae 500 million years ago.

360 MYAOrigin of the seed

150 MYAAngiospermsFlowering plants

MYA=Million Years Ago



This is the fossil records of some protists and plant groups. The width of the shaded area is an indicator of the number of species.

Fossil Records of Plants

Algae is the oldest and angiosperm is the most recent.

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From a single ancestral organism thought to be algae,

Ancestral organism

Ancestral Origin of Plants

t oug t to be a gae,a host of land plants

evolved with even greater complexity.

Stramenopiles “Brown Plants”

Red algae “Red Plants”

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Chlorophytes

Charophytes

Embryophytes

“GreenPlants”



Invasion of the Land

Embryophytes invaded land about

500 million years ago. What were some of

Water not as readily available and rapidly lost from plant in the

Dispersal of gametes is much more

difficult outside challenges they had

to overcome?

from plant in the terrestrial

environment.of an aquatic environment.

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Gravity prevented

vertical growth.

Difficulties on the Land

Temperature regulationDesiccationOther problems

plants faced when they

ReproductionSupport

Gas exchange

when they invaded the

land included:

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Dispersal



Adaptation From Water to Land

Plants adapted by becoming multicellular on land and

developing a thicker cell wall toThey also developed a transport system fordeveloping a thicker cell wall to

prevent drying.transport system for

nutrients and minerals, as well as root, stems, leaves

and seeds

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Plant Diversity

Embryophytes

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Plant Species

Plant Kingdom

Plant Life Cycle



Embryophytes: Role of Tracheids

Tracheids are specialized cells for conducting water. When plants

moved onto the land, some of them developed these cells and are The first plants on earth

called tracheophytes. Those that didn’t are called non-

tracheophytes.

placked vascular tissue or like

some mosses, had very simple conducting tissue that

developed from dead cells.

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Diversity of Embryophytes

Embryophytes 10 Phyla

Tracheophytes 7 Phyla

Non-Tracheophytes 3 Ph l

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7 Phyla

Have well developed vascular systems

3 Phyla

Lack tracheidsMembers: mosses, hornworts and liverworts



From Green Algae to Plants

ChlorophytesAncestral

alga

Charophytes

Liverworts Hornworts

Mosses

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Club mosses

FernGymnosperm

Angiosperm

Reproduction of EmbryophytesReproduction Evolution For Land Plants

Gametes must be dispersed in a non

Plants adapted by producing gametes within gametangia

aquatic environment. and the egg gets fertilized within the female organ.

The zygote develops into an embryo that was retained within

the protective cells of the female’s gametangia

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Embryos must be protected from desiccation.

female s gametangia.

This adaptation results in plants being referred as

embryophytes.



Species of PlantsMore than 300,000 plants are estimated to exist. Many thousands remain unknown.

GymnospermsAngiosperms y p

300,000 1000

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Plant Kingdom: CharacteristicsMore than 300,000

species existOften have plastids in

cytoplasm

.

Cell wall is made of cellulose

Store reserve food as starch

Generate energy by photosynthesis

20/59 Contains multicellular phototrophsUsually live on land, but

some live on water

y p y

Contain chlorophyll and beta carotene



Unique Characteristics of Plants

Most plants reproduce sexually and are capable of

l ti

Meiosis produces spores that develop

into multicellular haploid individualsasexual propagation

Alternation of generations is a universal feature

of the life cycles of

haploid individuals

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plants.

Life cycle includes both multicellular diploid and

multicellular haploid individuals

Gametes are produced by mitosis

Plant Life CycleThe 2N sporophyte undergoes meiosis

making a 1n reproductive cell called a spore. The spore undergoes mitosis to produce a

gametophyte.

The gametophyte makes a haploid

gamete that fuses to form a diploid

zygote sporophytezygote sporophyte.

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Alternation between haploid (gametophyte) and diploid (sporophyte)

generations is a distinctive feature of plants.



Alternation of Generations

Multicellular Gametophyte

Meiosis Fertilization

Spore GametesHaploid (n)

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Multicellular sporophyte

ZygoteDiploid (2n)

Plant Classification

Introduction

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Bryophytes

Tracheophytes

Gymnosperms

Angiosperms



Plant Classification Introduction

There are two major plant divisions depending on if the plant is a non-vascular (Bryophyte) or a vascular plant.

Notice the types and similarities between the groups.

Nonvascularplants

Vascularplants

25/59 Algae Liverworts

Hornworts

Mosses

Club mosses

Fern

GymnospermAngiosperm

Bryophytes : Introduction

Require a constantly moist environment

Evolved 500 million years ago

No roots but root like structures known as rhizoids

Earliest land plantsLiverworts

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Bryophytes Division Members

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Mosses (Bryophyta)

Hornworts (Anthocerophyta)

Liverworts (Hepatophyta)

Many grow in dense

Have leaf like structures that catch and hold water that splashes onto them.

Bryophytes: Features

Small enough that minerals can be distributed evenly by

diffusion.

Many grow in dense masses through which water can

move by capillary action.

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Basic Characteristics of Bryophytes

1. Maternal tissues prevent loss of water from the embryo

2. Grow in all 6 continents and on the coast of Antarctica.

3. Grow in dense moist habitats and are usually small.

4. Have a thin cuticle that is not very

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effective in retarding water loss.

Absorb water via filaments

Liverworts

Most ancient surviving plants

A l

Several genera have both sexual and asexual

reproduction

Absorb water via filaments located on the lower surfaces of gametophytes.

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Asexual reproduction is by

simple fragmentation of the

gametophyte.

p



Hornworts

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The hornworts, phylum mosses and tracheophytes, all have special adaptations

for life on land.

These plants have (pores) stomata that allow the uptake of CO2 and the release of O2,

but these pores can be closed to prevent excessive water

loss.

Non-Tracheophytes

Non

Spores germinate and give rise to a

multicellular, haploid tracheophytes Visible green

structure is the gametophyte.

S h t d

gametophyte whose cells contain chloroplasts.

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Sporophyte produces unicellular, haploid

spores through meiosis within sporangium or

capsules.



The zygote develops into a sporophyte which produces 1N spores in the sporangia which

germinate into another gametophyte.

Reproduction in Bryophytes

Female gametangia are called

The male antheridium produces sperm.

Water is required for the sperm to swim to the archegonium.

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The haploid gametophyte makes

haploid gametes.

are called archegonium and produces eggs.

Tracheophytes: Introduction

Sporophyte generation of a now extinct organism

produced a new cell type called Tracheid

Tracheid is the principal water

conducting element in the xylem of all

Early vascular plants had no roots, leaves,

fruits or flowers.

called Tracheid. ytracheophytes except

the angiosperms.

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Tracheids



History of TracheophytesFirst tracheophytes Phylum Rhyniophyta

Had the basic structures observed in all other tracheophyte phyla

Club mosses (Lycophyta)

Ferns horsetails and whisk

Silurian PeriodDevonian Period

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Ferns, horsetails and whisk ferns (Pteridophyta)

Lycophyta and Pteridophyta have true roots, true leaves, and a

differentiation between two types of spores.

Development of Tracheids

Evolution of tracheids had two important applications. First it allowed for a pathway to transport food and minerals.Second it provided rigid structural support for vertical growth.

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Tracheophytes have a branching independent sporophyte.



Club mosses Horsetails Whisk fern

Branching independent sporophyte

Multiflagellate sperm, complex

leaves

Evolution of Today’s Plants

Club mosses Horsetails Whisk fern

Fern

Seeds

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CycadsConifers

Ginkgos Gnetophytes

AngiospermsFlowers

The mature fern is diploid 2N sporophyte.

Ferns and their allies have a

heteromorphic alternation of

Reproduction - Gametophytes

The plant creates 1N spores by

meiosis dispersed by the wind.

The diploid zygote then grows out of the prothallus as the sporophyte.

generations.

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The prothallus carries out sexual reproduction making a 2N zygote.

The spore germinates and

grows into a haploid prothallus.



Roots have their origins as branches, either as rhizomes or

Early roots were simple structures that penetrated

the soil, branching and anchoring the plant.

Characteristics of Tracheophytes

above ground portion of stems.

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Plant Divisions

Vascular Plants TracheophytesVascular Plants

Includes seedless plants

Seed bearing forms

Tracheophytes

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Specialized transport cells

Xylem Transport water and minerals

Phloem Transports sugars

These plants are more complex and organized



Most plants above the fern have

magaphyllous leaves.

The term leaf gap denotes a gap in the

vascular cylinder above the leaf insertion.

Formation of Leaf Gaps

The petiole is the leaf stem and stipules are the small

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processes at the base of the

petiole.

Vegetative Stem:

N=node, I=internode, B=branch in

whorl, L=fused megaphylls

Seedless Tracheophytes

Horse tailsClub moss

Examples of seedless tracheophytes.

Horse tailsClub moss

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Ground pines Ferns- Most common vascular plants



Horsetails

Only living genus is equisetum

Live in damp locations and have flagellated

sperm

Most are homosporous

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Some have photosynthetic gametophytes

Ferns

Most common

Look on the under side of a fern and you will see their many

sporangia.

Most common seedless plant

Leaves have a branched vein

system

Water is necessary for

fertilization

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Sporophylls bear sporangia

on their underside

Gametophyte is fragile & requires a

moist habitat



Seed Bearing Tracheophytes

Successful due to

Seed Bearing Plants

Efficient vascular system

Two types of seed bearing tracheophytes

Extensive root system

XylemPhloem

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Gymnosperms

Angiosperms Flowering plants

Naked seed plants such as Conifers

GymnospermsGymnosperms contain

cycads and conifer. The seeds are naked and not

enclosed in a pericarp as in . angiosperms.

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Tracheids transport water and sieve cells carry organic

materials.Pine cones



AngiospermsAngiosperms or flowering plants may be either monocots or dicots.

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Monocots have parallel veined leaves and floral parts in 3’s.

Dicots have net-veined leaves and floral parts

in 4’s and 5’s.

Plant Adaptations

Leaves and StemsGrowth

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GrowthSeed ProductionPollenSpecial Adaptation of Flowering PlantsSenescence and Death



Adaptation of Leaves and Stems

Have stomata to regulate water loss, and chlorophyll to absorb light.

Leaves and stems adapted to absorb light and CO2. They are protected by a waxy covering to prevent loss of waterprevent loss of water.

Leaves have a rigid structure to prevent wilting.

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Plant Adaptability in GrowthLignin is a chemical compound derived

from wood and is an integral part of the cell

walls of plants

One possible form of lignin.

walls of plants.

Lignin provides skeletal support maintains plant

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support, maintains plant rigidity and reinforces

cellulose.

Lignin is important in plant evolution because it enables

plants to grow vertically.



Seed Production

So why is seed development so critical to

plant evolution?

Seed production is important because seeds can survive for many years and in harsh

conditions.

It is a good method to disperse the plants into new

habitats and avoid inbreeding.

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Also the seeds protect the plant from pathogens and

competition.

Role of Pollen

Male Gametophyte

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It can be blown/travel great distances by wind/insects.



Adaptations of Angiosperms

Flowering plants have special adaptation to help them survive. For instance they are designed to attract

pollinatorspollinators.

Also they have developed a co-evolution with insects that help them to survive, such

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p ,as pollinators.

Their fruits and seeds are designed to aid in their

dispersal.

Flower Specialization

Flowers became specialized to help them survive and

evolve. Some of their adaptations included color,

Adaptations of growth characteristics include: radial or symmetrical,

complete or incomplete. adaptations included color, nectar and odor.

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Characteristics of flower shape included single versus composite and

perfect versus imperfect.



Senescence and Death

Annual plants live one Perennials live two Annual plants live one season and die. years or more.

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Question: ReviewWhat kingdom do plants belong to?

___________Plantae

Fossil evidence indicates ___________

___________

Green algae

Non-vascular

T h h t

Fossil evidence indicates plants evolved from ______.

Green plant having a vascular

Of the two major plant divisions the Bryophyte is __.

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___________Tracheophytep gsystem: ferns, gymnosperms, angiosperms.

A chemical compound derived from wood and a important component of plant cell walls.

___________Lignin



Learning Summary

Embryophytes are the plants

that produce an

Embryophytes are the plants

that produce anPlants are the multicellular

Plants are the multicellular

Non vascular plants are the

most primitive.

Non vascular plants are the

most primitive.that produce an embryo that is

protected by the parent plant.

that produce an embryo that is

protected by the parent plant.

photosynthetic organisms

evolved from green algae.

photosynthetic organisms

evolved from green algae.

most primitive.Vascular plants allow transport

of water and minerals.

most primitive.Vascular plants allow transport

of water and minerals.

Pl t d t d tPl t d t d t

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Plants reproduce sexually and

have ability of asexual

propagation.

Plants reproduce sexually and

have ability of asexual

propagation.

Plants adapted to land by having

cuticle, stomata, gametangia,

pigments and spores.

Plants adapted to land by having

cuticle, stomata, gametangia,

pigments and spores.

Congratulations

You have successfully completed the core tutorial

Plant Evolution and Diversity

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Pl t E l ti & Di itPlant Evolution & Diversity · First tracheophytes Phylum Rhyniophyta Had the basic structures observed in all other tracheophyte phyla Club mosses (Lycophyta)