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Watch
the Power Point The Seedless Vascular Plants: Ferns and Their
Relatives. We will concentrate on the Ferns. Read pages 22 – 31 in
Chapter 2 in the study guide on Ferns. Then complete the assignment:
The Laboratory Examination of the Fern draftTHIS IS A VERY EASY ASSIGNMENT, I AM SENDING YOU ALL THE INFORMATION YOU NEED AS IT WILL BE LINKED IN THE ATTACHMENTS BELOW. A PERFECT SCORE IS NEEDED, SO PLEASE DO YOUR BEST ON THIS.
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Chapter 21
Lecture Outline
The Seedless Vascular
Plants: Ferns and Their
Relatives
Copyright © McGraw-Hill Education. Permission required for reproduction or display.
©McGraw-Hill Education.
Outline
Introduction
Phylum Psilotophyta – The Whisk Ferns
Phylum Lycophyta – The Ground Pines,
Spike Mosses and Quillworts
Phylum Equisetophyta – The Horsetails
and Scouring Rushes
Phylum Polypodiophyta – The Ferns
Fossils
©McGraw-Hill Education.
Introduction
During early stages of vascular plant
evolution:
Internal conducting tissue developed.
True leaves appeared.
Roots that function in absorption and
anchorage developed.
Gametophytes became progressively
smaller.
Four phyla of seedless vascular plants:
Psilotophyta, Lycophyta, Equisetophyta,
Polypodiophyta
©McGraw-Hill Education.
Introduction (2)
Psilotophyta
Sporophytes have neither true
leaves, nor roots.
Stems and rhizomes fork
evenly.
Lycophyta
Plants covered with
microphylls.
Microphylls – Leaves with
single vein whose trace is
not associated with a leaf
gap
Psilotum
Lycopodium
©McGraw-Hill Education.
Introduction (3)
Equisetophyta
Sporophytes have ribbed stems
containing silica.
Have whorled, scalelike
microphylls that lack
chlorophyll
Polypodiophyta
Sporophytes have megaphylls
that are often large and much
divided.
Megaphylls – Leaves with
more than one vein and a
leaf trace associated with
leaf gap
Equisetum
A fern
©McGraw-Hill Education.
Phylum Psilotophyta – The Whisk Ferns
❖
Resemble small, green whisk brooms
Structure and form:
Sporophytes:
Dichotomously forking stems
Above ground stems arise from
rhizomes beneath surface of
ground.
Have neither leaves nor roots
Enations along stems.
Enations – Tiny, green,
superficially leaflike, veinless,
photosynthetic flaps of tissue
Rhizoids, aided by mycorrhizal
fungi, scattered along rhizomes.
©McGraw-Hill Education.
Phylum Psilotophyta – The Whisk Ferns (2)
Reproduction:
Sporangia fused in threes and produced
at tips of short branches.
Gametophytes develop from spores
beneath ground.
Branch dichotomously
No chlorophyll
Rhizoids aided by mycorrhizal fungi.
Archegonia and antheridia scattered
on surface.
Zygote develops foot and rhizome.
Rhizome separates from foot.
©McGraw-Hill Education.
Phylum Psilotophyta – The Whisk Ferns (3)
Reproduction:
©McGraw-Hill Education.
Phylum Psilotophyta – The Whisk Ferns (4)
Fossil whisk fern look-alikes:
Silurian, 400 million years ago
Cooksonia and Rhynia
Naked stems and terminal
sporangia
Devonian, 400-350 million years ago
Zosterophyllum
Naked stems and rounded
sporangia along stem
Thought to be ancestral to club
mosses
©McGraw-Hill Education.
Phylum Lycophyta – The Ground Pines, Spike
Mosses, and Quillworts
Collectively called club mosses
Two living major genera
Lycopodium
Selaginella
Two living minor genera
Several genera that became
extinct about 270 million years
ago
Sporophytes have microphylls.
Have true roots and stems
©McGraw-Hill Education.
Phylum Lycophyta
Lycopodium – Ground pines
Often grow on forest
floors
Stems are simple or
branched.
Develop from
branching rhizomes
Leaves usually less than 1
cm long.
Roots develop along
rhizomes.
©McGraw-Hill Education.
Phylum Lycophyta (2)
❖
Lycopodium reproduction:
Sporangia in axils of
sporophylls.
Sporophyll – Sporangiumbearing leaves
In some species,
sporophylls have no
chlorophyll, are smaller
than other leaves and
clustered into strobili
(singular: strobus).
• In sporangia, sporocytes undergo meiosis,
producing spores.
©McGraw-Hill Education.
Phylum Lycophyta (3)
Lycopodium reproduction:
Spores grow into independent
gametophytes.
In some species, gametophytes
resemble tiny carrots, develop in
the ground and are associated
with mycorrhizal fungi.
In others, gametophytes develop
on surface and are green.
Archegonia and antheridia
produced on gametophytes.
Sperm are flagellated and water is
essential for fertilization.
©McGraw-Hill Education.
Phylum Lycophyta (4)
Lycopodium reproduction:
©McGraw-Hill Education.
Phylum Lycophyta (5)
Selaginella – Spike mosses
Especially abundant in tropics
Branch more freely than ground pines
Leaves have a ligule on upper surface.
©McGraw-Hill Education.
Phylum Lycophyta (6)
Selaginella reproduction:
Produce two different kinds of gametophytes =
heterospory.
Microsporophylls bear microsporangia containing
microsporocytes, producing tiny microspores.
Microspore becomes male gametophyte, consisting
of an antheridium within microspore wall.
Megasporophylls bear megasporangia containing
megasporocytes, producing 4 large megaspores.
Megaspore develops into female gametophyte
consisting of many cells inside megaspore.
Several archegonia produced where spore wall
ruptures.
©McGraw-Hill Education.
Phylum Lycophyta (7)
Selaginella
reproduction:
©McGraw-Hill Education.
Phylum Lycophyta (8)
Isoetes – Quillworts
• Most found in areas partially submerged in water
for part of year.
• Microphylls are arranged in a tight spiral on a
stubby stem.
• Ligules occur towards
leaf bases.
• Corms have vascular
cambium.
• Plants generally less
than 10 cm tall.
©McGraw-Hill Education.
Phylum Lycophyta (9)
Isoetes
reproduction:
Similar to spike
mosses, except
no strobili
Sporangia at
bases of
leaves.
©McGraw-Hill Education.
Phylum Lycophyta (10)
Ancient relatives of club
mosses and quillworts:
Dominant members of
forests and swamps of
Carboniferous, 325
million years ago
Large, tree-like, up
to 30 meters tall Lepidodendron
Surface of Lepidodendron,
showing microphyll bases
©McGraw-Hill Education.
Phylum Equisetophyta – The Horsetails and
Scouring Rushes
Equisetum
Branched and unbranched forms,
usually less than 1.3 meters tall
Stems jointed and ribbed.
If branched, then branches in
whorls.
Scalelike leaves in whorls at
nodes.
Stomata in grooves between
ribs.
©McGraw-Hill Education.
Phylum Equisetophyta
Stem anatomy:
Hollow central cavity from break down of pith
Two cylinders of smaller canals outside pith.
– Carinal canals
conduct water
with xylem and
phloem to
outside.
– Vallecular
canals outside
carinal canals
contain air.
❖
Silica deposits on walls of stem epidermal cells.
©McGraw-Hill Education.
Phylum Equisetophyta (2)
Equisetum reproduction:
Asexual by fragmentation of
rhizomes
Sexual reproduction:
Strobili at tips of stems
with sporangia
connected to
sporangiophores.
Spores green with 4
ribbon-like elaters
attached.
Aid in spore dispersal
Gametophytes lobed,
green, cushionlike, up to
8 mm in diameter.
©McGraw-Hill Education.
Spores with
elaters
Phylum Equisetophyta (3)
Equisetum reproduction:
©McGraw-Hill Education.
Phylum Equisetophyta (4)
Ancient relatives of horsetails:
Flourished in Carboniferous,
300 million years ago.
Human and ecological relevance:
Many giant horsetails used for
food by humans and other
animals.
Scouring rush stems used for
scouring and sharpening.
Reconstruction of fossil giant
horsetail, Calamites
©McGraw-Hill Education.
Phylum Polypodiophyta – The Ferns
Structure and form:
Vary in size from tiny floating forms less than 1 cm to
giant tropical tree ferns up to 25 m tall
Fern leaves are megaphylls – Referred to as fronds.
Typically divided into smaller segments
Require external water for reproduction
©McGraw-Hill Education.
Phylum
Polypodiophyta –
The Ferns (2)
Reproduction:
Sporophyte is conspicuous
phase.
Fronds, rhizomes, roots
Fronds first appear coiled
in crozier (fiddlehead),
and then unroll and
expand.
Fronds often divided
into segments called
pinnae (singular:
pinna).
©McGraw-Hill Education.
Crozier
Phylum Polypodiophyta – The Ferns (3)
Reproduction:
Sporangia stalked.
May be scattered on lower
leaf surface, confined to
margins, or found in discrete
clusters called sori (singular:
sorus).
Sori may be protected by
indusia (singular:
indusium).
With row of heavy-walled,
brownish cells = annulus
Annulus catapults spores
out of sporangium.
©McGraw-Hill Education.
Sorus covered by
indusium
Phylum Polypodiophyta – The Ferns (4)
Reproduction:
Meiosis forms spores in sporangia.
Spores released and grow into gametophytes
called prothalli (singular: prothallus).
• Prothalli are one cell thick,
and have archegonia and
antheridia.
• Zygote develops into young
sporophyte.
• Gametophyte, or portion of
it, dies and leaves
sporophyte growing
independently.
©McGraw-Hill Education.
Phylum Polypodiophyta – The Ferns (5)
Reproduction:
©McGraw-Hill Education.
Phylum Polypodiophyta – The Ferns (6)
• Devonian, 375 million
years ago – Fossil
relatives of ferns
–
Resemble ferns in
growth habit, but look
more like whisk ferns
Possible ancestors: Aglaophyton and Psilophyton
©McGraw-Hill Education.
Phylum Polypodiophyta – The Ferns (7)
Fossil relatives of ferns
Carboniferous, 320-250 million
years ago – Tree ferns abundant
Seeds found on some of
fossil tree ferns.
©McGraw-Hill Education.
Phylum Polypodiophyta
Human and ecological relevance:
House plants
Function well as air filters
Outdoor ornamentals
Cooked rhizomes as food
Folk medicine
Fronds used in thatching for
houses.
Basketry and weaving
©McGraw-Hill Education.
Fossils
A fossil – Any recognizable prehistoric organic
object preserved from past geological ages.
Conditions of formation almost always
include quick burial and an accumulation of
sediments.
Hard parts more likely preserved than soft
parts.
©McGraw-Hill Education.
Fossils (2)
Molds, casts, compressions, and imprints:
After being buried in sediment and hardened into
rock, organic material slowly washed away.
–
If air space remains – Mold
–
If silica fills space – Cast
• Compression – Objects buried by layers
of sediment and overlying sheer weight
compresses them to thin film of organic
material and an outline.
–
Image of an impression = imprint
–
Coal is a specific type of compression.
Compression fossil
©McGraw-Hill Education.
Fossils (3)
Petrifactions – Uncompressed rock-like material in which
original cell structure has been preserved
Chemicals in solution infiltrate cells and cell walls, where they
crystallize and harden, preserving original material.
Coprolites – Dung of
prehistoric animals and
humans
Unaltered fossils – Organisms
fell into oil or water that
lacked oxygen and did not
permit decay.
Petrified wood
©McGraw-Hill Education.
Review
Introduction
Phylum Psilotophyta – The Whisk
Ferns
Phylum Lycophyta – The Ground
Pines, Spike Mosses and Quillworts
Phylum Equisetophyta – The
Horsetails and Scouring Rushes
Phylum Polypodiophyta – The
Ferns
Fossils
©McGraw-Hill Education.
©McGraw-Hill Education.
Laboratory Examination of the Fern
Name ____________________
Total points =
1. The fern has a life cycle that demonstrates alternation of generations.
Name the two stages that alternate during the life cycle of the fern. 2 points
Define the terms haploid and diploid. 4 points
Which stage of the life cycle is haploid and which stage is diploid? 2 points
What reproductive structures (cells) are produced by each stage in the life
cycle? 4 points
Which stage of the life cycle is dominant in the ferns? Is this stage
independent? Explain 4 points
2. Does the fern have true roots, stems, and leaves? 2 points
What three characteristics make these structures “true”? 6 points
3. What is the fern stem called? What is the definition of this structure? 4
points
The fern rhizome is found underground where we would normally find roots.
However it is considered to be a stem. Explain. 4 points
4. What is the term for a fern leaf? 2 points
The fern leaf is divided into individual leaflets that are arranged along the
sides of a common axis. What term is used to describe this? 2 points
5. What is the term that describes the roots in ferns? Define this term. 4 points
6. Examine the picture showing a fern leaf with sori. Where are the sporeproducing structures, the sori located in the fern Polypodium? 2 points
Describe the indusium. What is its function? 4 points
1
7. What environmental factor causes spore dispersal in the fern? 2 points
Where does the sporangium break open? 2 points
Describe the changes in the position of the annulus that lead to spore
dispersal. Refer to the study guide. 4 points
Name two other plants that we have studied previously in which this same
environmental factor causes the dispersal of spores. For each of those
plants, explain the mechanism that is responsible for the dispersal of the
spores into the wind. 6 points
8. What is the function of the xylem? What is the function of the phloem?
4 points
What advantage does the possession of vascular tissue, having the functions
indicated above, make possible for the plant? 2 points
9. Examine the picture of a fern gametophyte showing antheridia and
archegonia.
Where are the antheridia located? Use anatomical terminology to indicate
the surface. 2 points
Where are the archegonia located? Use anatomical terminology to indicate
the surface. 2 points
Fern gametophytes are monoecious. What does this term mean? 2 points
10. Rather than fertilizing their own eggs, the sperm travel to archegonia located
on other gametophytes.
What is the mechanism that results in cross-fertilization? 4 points
What advantages does cross fertilization give to the fern plant? 4 points
11. Examine the sperm inside the antheridium.
Are the sperm flagellated? 2 points
2
How do the sperm get to the egg? 2 points
What is the evolutionary significance of this? 4 Points
12. Examine several archegonia under high power.
Describe the parts of the archegonium. 6 points
Examine the picture showing a young sporophyte growing from a
gametophyte.
What is the relationship between the sporophyte and gametophyte at this
time? 2 points
Will the sporophyte become an independent plant? Approximately how long
does this take? 4 points
3
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