Seedless Plants

Plant Evolution

This is what we

discussed from

exam 1. Plants

(embryophtes)

sister taxa is the

green algae

Charophyceans

Plant Evolution

Nonvascular Seedless plants

– (Ordovician - 475 mya)

Vascular Seedless plants

– (Devonian - 400 mya)

Vascular Seed plants

– (Carboniferous - 360 mya)

Flowering plants

– (Cretaceous - 130 mya)

Plant Evolution(Common with Algae)

Multicellular and Eukaryotic

Cell walls made of Cellulose

Chlorophyll a and b

Store excess sugar as starch

Adaptations to Terrestrial Life

Apical Meristems

Multicellular Dependent Embryos

Alternation of Generation

Walled Spores produced in Sporangia

Other Adaptations

– Cuticle, stomata, Xylem & Phloem,

secondary compounds

Apical Meristems

These are localized

regions of cell division at

the tips of shoots (left)

and the tips of roots

(right). These cells can

divide throughout the

plants life and allows for

growth and

environmental resources.

Multicellular Dependent Embryos

A Significant change

is the development of

these embryos from

zygotes. The

parental tissue

protect the embryo

and supplies

nutrients such as

sugars and amino

acids.

Alternation of Generation

We saw this in

different algaes

(Brown, Red,

Green) but it

differs because

both stages

(haploid and

diploid) have

multicellular

organisms

Walled Spores produced in Sporangia

Sporopollenin (a

durable

polymer)

surrounds the

spores formed

by a

multicellular

structure called

sporangia

Other Adaptations Cuticle (top) – some plants have

evolved a covering made of wax

and other polymers to resist drying

out

Stomata (middle) – some plants

have evolved specialized pores

that allow for gas exchange but

also deal with water retention.

Xylem and Pholem (bottom) –

vascular tissue seen in “vascular”

plants to transport water and food

accordingly

Secondary compounds (not

shown) are produced by plants for

the protection from predation

Adaptations in Shallow Water Algae

Subjected to occasional drying

Protection of gametes and embryos in

gametangia (a specialized organ or cell in

which gametes are formed in algae, ferns,

and some other plants – (you saw this in

Fucus (Oogonia and Antheridium)

Sporopollenin (waxy polymer to prevent

zygotes from drying out) – seen in

charophytes

Classification of Seedless Plants

Nonvascular Seedless

plants (n)

– Bryophyta

Mosses

– Hepatophyta

Liverworts

– Anthocerophyta

Hornworts

Vascular Seedless

plants (2n)

– Lycophyta

Club mosses

– Psilophyta

Whiskferns

– Spenophyta

Horsetails

– Pterophyta

Ferns

Nonvascular Seedless Plants

The plant is a thallus (no vascular

tissue)

– no true leaves, roots, stems

They are Embryophytes

– They have gametangia

(antheridium and archegonium)

– They have sporangia (produces

spores)

Alternation of Generation

Nonvascular Seedless Plants

They are represented by Liverworts,

Hornworts and Mosses shown as (a) in the

slide before

The “plant” is the part of the gametophyte

generation and is haploid

The sporophyte generation is small and

completely dependent on the gametophyte

generation

Hepatophyta Liverworts (n) – the

name comes from the

“liver” shape of the

gametophytes. In

medieval times, it was

thought this plant could

help treat liver disease.

They come in two forms

leafy (80%)

thalloid (20%)

Hepatophyta

Liverworts reproduce

asexually through

gemmae cups

The gemmae are a

haploid gametophyte that

will develop into a full

plant. Dispersal is done

when rain splashes into

the cup allowing the

gemmae to disperse.

Hepatophyta

Liverworts reproduce

sexually through

gametangia. Antheridia

produce sperm and

Archegonia produce

eggs. The sporophyte

that produces spores

will develop in the

archegonium once an

egg is fertilized by a

sperm

Anthocerophyta Hornworts are

similar to liverworts

except for the

sporophytes that

look like horns.

These are thought

to be the most

closely related to

vascular plants

BryophytaMosses

Bryophyta Mosses are usually found in moist habitats

Mosses are gametophyte dominant

– The “plant” looking part is haploid

– The male has antherdia (produce sperm)

– The female has archegonia (produce eggs)

The spores produce a haploid structure called a

protonema. This structure is made of filaments like

some green algae but it is branched.

The sporophyte is dependent on the gametophyte

– It always grows out of the female gametophyte

BryophytaMosses

(Life Cycle)

You will need to be able to draw

this

Vascular Seedless Plants

Formation of vascular tissue

– Xylem (water)

– Phloem (food)

– True leaves, roots, and stems

Lignin (polymer that strengthen

the cell wall in xylem)

Sporophyte generation dominate

Sperm with flagella

Alternation of Generation

Vascular Seedless Plants

They are represented by Lycophyta and

Pterophyta shown as (b) in the slide before

The “plant” is the part of the sporophyte

generation and is diploid

The gametophyte generation is small and

completely independent of the sporophyte

generation

Vascular Seedless Plants

This group has two Divisions

– Lycophyta – the Club Mosses, Spikemosses, and

Quillworts.

– Pterophyta which includes several types of plants

that were once in their own divisions. New

evidence suggests they are more closely related

Whisk Ferns (Psilophyta)

Horsetails (Spenophyta)

Ferns (Pterophyta)

Lycophyta Lycophytes include Club Mosses,

Spikemosses, and Quillworts. There

are very few left and they are

considered relic species.

Lycophytes have true leaves that are

small with a single strand of vascular

tissue and these leaves are called

microphylls

The also have true stems and true roots

They also have sporophylls that are

leaves that produce spores

Pterophyta (Psilophyta) This division

includes the Whisk

Ferns

The have no true

leaves and no true

roots – They are just

a stem. They may

have had leaves

once but they have

been lost.

Pterophyta (Sphenophyta)

This division includes

Horsetails

They have true leaves

called microphylls which

often die at maturity. The

true stems have silica in

them that give them a gritty

feel. The stems are where

most photosynthesis

occurs. They also have

true roots

Division: Pterophyta

Division: Pterophyta

Pterophyta (Ferns) Ferns are sporophyte dominant

– The “plant” looking part is Diploid

Unlike the other pterophytes, ferns have macrophylls

(large leaves with several or many large veins

branching apart or running parallel and connected by

a network of smaller veins). The name of fern

macrophylls is a frond.

The Gametophyte generation is a heart-shaped

structure called a prothallus.

– The male has antherdia (produce sperm)

– The female has archegonia (produce eggs)

Fern Life Cycle

You will

need to be

able to draw

this