seedless plants plantsfaculty.sxu.edu/dlc1/genbioweb19/w4 plants_seedless (1).pdf · 2/15/2019 1...

2/15/2019

1

Plants

(Seedless)

Learning Objectives

• By the end of this unit, a student should be able to…

• Describe the characteristics and distinguish among the major groups of

seedless plants

• Diagram the “alternation of generations” life cycle

• Discuss challenges of adapting to life on land and which adaptations in

plants evolved in response.

• Describe the evidence suggesting the hypothesized relationship between

plants and the charophytes

• Summarize the features that distinguish bryophytes from other plants

• Name and describe the phyla of bryophytes

• Compare the gametophyte and sporophyte generations in bryophytes

• Discuss features that distinguish seedless vascular plants from algae and

bryophytes

• Distinguish between the lycophytes and the ferns

ARCHAEPLASTIDS

• Red algae

• Green algae

• Land plants

• Monophyletic based on

• molecular data

• presence of chloroplasts bound by outer and inner membranes

Green Algae

• Wide diversity in

size, structural

complexity, and

reproduction

Charophytes

• Plants probably arose from charophytes

• a group of green algae

• close match between charophytes and plant DNA and

RNA sequences

Charophytes

• Plants probably arose from charophytes

• a group of green algae

• close match between charophytes and plant DNA and

RNA sequences

Gametangia in Charophytes are

different than other plants.

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5

–

–

– Zoospores

ASEXUAL

REPRODUCTION (by

mitosis)

–

–

4 Four haploid

cells emerge, two

(+)

and two

(-).

1 Gametes are produced

by mitosis. +

–

– – SEXUAL

REPRODUCTION

+ HAPLOID (n)

GENERATION

–

+ –

DIPLOID (2n)

GENERATION 2 (+) and (-)

gametes fuse,

forming a diploid

zygote.

+ Meiosis Fertilization

3

Meiosis

occurs. Zygote (2n)

Chlamydomonas

• Chlamydomonas has

isogamous sexual

reproduction

Ulva

• Ulva has

anisogamous

sexual reproduction

Plant Life Cycle

“Alternation of Generations”

Plant Life Cycle

• Alternation of Generations

• Haploid gametophyte

• produces gametes by

mitosis

• gametes fuse

(fertilization) to form

diploid zygote

• Diploid sporophyte

• Zygote develops into

multicellular embryo/plant

• produces sporogenous

cells (mother cells)

“Land Plants”

What are environmental challenges of living on land?

How do plant adaptations meet these challenges?

Colonization of Land by Plants

• Adaptations

• Anatomical

• of or relating to bodily structure

• Physiological

• of or relating to the way in which a living organism or

bodily part functions

• Reproductive

• of or relating to the production of offspring by a sexual

or asexual process

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Colonization of Land by Plants

• Cuticle

• waxy layer

• protects against water

loss

• Stomata (stomates)

• for gas exchange

needed for

photosynthesis –Johnny Appleseed

“Type a quote here.”

VASCULAR

SEEDLESS PLANTS

VASCULAR

SEED PLANTS

NONVASCULAR BRYOPHYTES

Ho

rnw

ort

s

Liv

erw

ort

s

Mo

sses

Clu

b m

osses

Fern

s

Gym

no

sp

erm

s

An

gio

sp

erm

s

Evolution of

seeds

Evolution of dominant

sporophyte, vascular

tissue

Evolution of cuticle,

multicellular gametangia,

multicellular embryos Green algal

ancestor

Bryophytes

• Bryophyte characteristics

• Nonvascular

• lack conducting tissues

• xylem & phloem

• must remain relatively small

• Gametophyte generation is dominant

• unlike other plant groups

• sporophytes remain permanently

attached

• nutritionally dependent on

gametophytes

Hornworts

• Phylum Anthocerophyta

• ~100-150 species

• Thalloid gametophytes

• Horn-like sporophytes

Liverworts

• Phylum Marchantiophyta

• ~ 9000 species

• Some have flattened, lobed thalloid gametophytes

• resemble lobes of the liver

• most are “Leafy” gametophytes

Fig. 27-4, p. 584

VASCULAR SEED PLANTS

Evolution of seeds

Evolution of dominant sporophyte, vascular

tissue

Evolution of cuticle, multicellular gametangia,

multicellular embryos

Green algal ancestor

Liverworts

• Pores, not stoma for gas

exchange

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Fig. 27-4, p. 584


Evolution of seeds


tissue




Liverworts

• Asexual Reproduction

• Gemmae cups

Fig. 27-4, p. 584


Evolution of seeds


tissue




Liverworts

• Sexual Reproduction

• Antheridophore

• hold antheridia

• Archegoniophore

• hold archegonia

Liverworts

• Liverwort sperm cell

Pellia epiphylla

Video of liverwort sperm

Fig. 27-4, p. 584


Evolution of seeds


tissue




Mosses

• Phylum Bryophyta

• ~12,000 spp.

• Gametophytes (n)

• grow from protonema

• branching, filamentous stage

Fig. 27-4, p. 584


Evolution of seeds


tissue




Mosses

• Phylum Bryophyta

• ~12,000 spp.

• Gametophytes (n)

• grow from protonema

• branching, filamentous stage

Mosses

Fig. 27-4, p. 584


Evolution of seeds


tissue




• Sporophytes (2n)

• produce capsules

• contain spores

https://www.youtube.com/watch?v=ALGDLzWcvnU

https://www.youtube.com/watch?v=ALGDLzWcvnU

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Seedless

Vascular

Plants

Ferns

Fern Allies

Lycopods

–Johnny Appleseed


VASCULAR

SEEDLESS PLANTS

VASCULAR

SEED PLANTS


Ho

rnw

ort

s

Liv

erw

ort

s

Mo

sses

Clu

b m

osses

Fern

s

Gym

no

sp

erm

s

An

gio

sp

erm

s

Evolution of

seeds

Evolution of dominant

sporophyte, vascular

tissue

Evolution of cuticle,

multicellular gametangia,

multicellular embryos Green algal

ancestor

Seedless Vascular Plants

• What features distinguish

seedless vascular plants from

algae and bryophytes?


• What features distinguish

seedless vascular plants from

algae and bryophytes?

xylem and phloem in a

lycopod stem cross section

Vascular tissue and much

larger, dominant sporophyte

Lepidodendron from the

carboniferous period


• In vascular plants

• xylem conducts water and

dissolved minerals

• phloem conducts dissolved sugar

xylem

xylem and phloem in a

lycopod stem cross section Lepidodendron from the

carboniferous period

phloem


• Sporophyte is larger

• increases spore dispersal

• gametophytes still need water for

reproduction

• sperm swim to eggs

xylem

“fern sperm”

fern gametophyte

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–Johnny Appleseed


Fig. 27-4, p. 584

VASCULAR SEEDLESS

PLANTS

VASCULAR SEED

PLANTS

NONVASCULAR BRYOPHYTES H

orn

wo

rts

Liv

erw

ort

s

Mo

sses

Clu

b m

osses

Fern

s

Gym

no

sp

erm

s

An

gio

sp

erm

s

Evolution of

seeds

Evolution of cuticle, multicellular

gametangia, multicellular embryos Green algal

ancestor

“Club Mosses” are the Lycopods

They are not mosses

Fig. 27-4, p. 584

VASCULAR SEEDLESS

PLANTS

VASCULAR SEED

PLANTS


Ho

rnw

ort

s

Liv

erw

ort

s

Mo

sses

Clu

b m

osses

Fern

s

An

gio

sp

erm

s

Evolution of

seeds



ancestor

Lycopods

• Lycopods have microphylls

• a different way of forming vascular tissue in the leaves

Stem Microphyll

Vascula

r tissue Enation

Vein

Smooth

stem Enation Vascular

supply to

enation

Microphyll

(one vein)

Lycopods

• 3 extant (not extinct) lineages

• there used to be more

Isoetes

Selaginella

Lycopodium

Lycopods

Lycopodium

• Lycopodium (ground pine)

• flammable spores!

Lycopods

Lycopodium

• Lycopodium (ground pine)

• flammable spores!

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Lycopods

Isoetes

• Isoetes (quillworts)

• mostly aquatic

• no stomata

• obtain CO2 From roots

Lycopods

Selaginella

• Selaginella (spike moss)

• Kinda cute

• Evolved heterospory

microspores megaspores

HOMOSPORY

HETEROSPORY

microspores

megaspores

give rise to female gametophytes

that produce eggs

give rise to male gametophytes

that produce sperm

Lycopods

• Selaginella (spike moss)

• Gametophytes highly

reduced

• Much like a seed

• (convergent evolution)

Selaginella Life Cycle

Remember that

the life cycle is

the same in all

plants!

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Fig. 27-4, p. 584

VASCULAR SEEDLESS

PLANTS

VASCULAR SEED

PLANTS


Ho

rnw

ort

s

Liv

erw

ort

s

Mo

sses

Clu

b m

osses

Fern

s

Gym

no

sp

erm

s

An

gio

sp

erm

s

Evolution of

seeds

“Club Mosses” = Lycopods



ancestor

Fig. 27-4, p. 584

VASCULAR SEEDLESS

PLANTS

VASCULAR SEED

PLANTS


Ho

rnw

ort

s

Liv

erw

ort

s

Mo

sses

Clu

b m

osses

Fern

s

Gym

no

sp

erm

s

An

gio

sp

erm

s

Evolution of

seeds



ancestor

FERNS (PHYLUM PTERIDOPHYTA)

Psilotum

Equisetum

“Ferns”

Ferns (Phylum? Division?)

Psilotum

Ferns

• Psilotum (Whisk Fern)

• Leafless, dichotomous branches

• “odd” sporangia

Psilotum

Ferns

• Psilotum (Whisk Fern)

• small non-photosynthetic

gametophytes

• but with vascular tissue!

• nourished by mychorrizae Thinner

side

branch

Dichotomously

branching stems

Overtopping

(unequal

branching)

Planation

(branching in

same plane)

Webbing of side

branch system

Megaphyll (many

veins)

Equal branches

Vascular tissue

Ferns

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Thinner

side

branch

Dichotomously

branching stems

Overtopping

(unequal

branching)

Planation

(branching in

same plane)

Webbing of side

branch system

Megaphyll (many

veins)

Equal branches

Vascular tissue

Ferns

• Sporophytes have megaphylls (leaves)

Megaphyll vs. Microphyll

• Sporophytes consist of roots, rhizomes, erect

branches, and microphylls (leaves)

Psilotum

Equisetum “Ferns”


Equisetum


Ferns

• Equisetum

• hollow, jointed roots, rhizomes, aerial

stems

• strobili

Strobilus

Vegetative

shoots

Reproductive

shoots

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Ferns

• Equisetum

• Large, tree-like species now extinct

• once prominent

• The “Coal Age” (Carboniferous)

Psilotum

Equisetum “Ferns”

FERNS

FERNS • Largest and most diverse group of seedless vascular plants

• Sporophyte leaves are called fronds

• often unfurl during development

FERNS

• Sporophyte has a rhizome

• Horizontal, underground stem

• bears fronds

• has true roots

FERNS

Rhizome

• Fronds contain sporangia

• Clustered in a Sorus

• produces many spores!

FERNS

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• Fronds contain sporangia

• Clustered in a Sorus

FERN GAMETOPHYTE • Fern Gametophyte is called a prothallus

• develops from haploid spore

• bears both archegonia and antheridia

FERN LIFE CYCLE

seedless plants plantsfaculty.sxu.edu/dlc1/genbioweb19/w4 plants_seedless (1).pdf · 2/15/2019 1...

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