nonvascular seedless plants - mt. san antonio college
TRANSCRIPT
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)
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
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
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
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
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)