Transcript kingdom_plantae_phylax

Early Plants
• The earliest plants were
similar to today’s
mosses. They grew
close to damp ground
and depended on water
to complete their life
cycles (to carry the
gametes).
Kingdom Plantae (page 550)
• Characteristics:
- eukaryotic
- multicellular (most)
- have cell walls made of a complex
carbohydrate called cellulose
- sessile (anchored by roots)
- Autotrophic - Contain chlorophyll in
chloroplasts within their cells. (The green
pigment necessary for photosynthesis) Some
plants though, are also parasitic or saprobes.
-Reproduce both sexually (production of sex
gametes) and asexually (fragmentation,
budding, spores)
Life cycle (page 552)
- Undergo a life cycle called “alternation of
generations”.
This means the plant alternates between a
gametophyte (produces gametes/haploid
cells) and a sporophyte (produces
spores/diploid cells).
One generation is usually dominant.
Land plants
• Land plants are first divided into non-vascular
and vascular plants.
• Vascular plants have a system of “vessels” that
carry food and water around. Non-vascular
plants do not.
• Special cells, called tracheids which transport
water were developed.
• Tracheids are hollow cells with thick cell walls
that resist osmotic pressure. They join
together and die, leaving a long hollow tube
like a straw.
• Tracheids allowed for the development of
vessels and vascular plants.
• Xylum is the transport
system in plants that
carries water.
• Phloem transports the
solutions of nutrients
and carbohydrates
produced by
photosynthesis.
Xylem and Phloem
Phylum Bryophyta (Bryophytes)
(mosses and their relatives)
• Non-vascular plants
• No “tissues”
• Depend on water for
reproduction (HOW?)
• Draw up water by
osmosis only
• Have to be short,
growing only a few
centimeters above
ground (WHY?)
Phylum Bryophyta continued
• The sperm must swim
to reach neighbouring
eggs
• Must live in, near water
or heavy dew for at
least some of the year.
(near streams, forest
floor)
Phylum Bryophyta continued
• Can tolerate low
temperatures and fairly
harsh climates
• ”leaves” are only one
cell thick
• has rhizoids rather than
true roots
• In the life cycles of
plants, there are two
“generations” (phases) ;
gametophyte or
sporophyte.
• Gametophyte is the
dominant generation
(Moss spends most of
its life cycle in this
generation).
Life Cycle of a Bryophyte, including
peat moss (page 558)
• Moss spore lands in a
moist place
• Germinates and grows
into protonema.
• As the protonema
grows, it forms rhizoids
that grow into the
ground and shoots that
grow into the air.
Bryophyte Life Cycle
• The shoots are the
gametophyte stage of
the moss’s life cycle and
this is what we see and
think of as “moss”
• http://www.youtube.com/watch?v=jcWYAnm
m-QE
Know this!
• Antheridium (antheridia – plural)
• Archegonium (archegonia - plural).
• Homework:
Questions 1, 3, 4, and 5 on page 559.
Vascular Plants
(all plants except those in the Phylum
Bryophyta)
• Ferns, herbs, trees, flowers, vegetables.
• The vascular system allows these plants to
transport nutrients and water throughout the
plant, even against gravity.
• Sporophyte generation is dominant (diploid)
• Gametophyte generation is short (haploid)
Seedless vascular plants (club mosses,
horsetails and ferns)
• Have:
Roots: underground organs that absorb water
and minerals. Water-conducting tissues are in
the center of the root
Leaves: photosynthetic organs that contain
one or more bundles of vascular systems
gathered into veins made of xylem and
phloem.
• Stems: supporting structures that connect
roots and leaves, carrying water and nutrients
between them
Phylum Pterophyta (ferns)
• Most numerous phylum
of seedless vascular
plants (over 11 000
species).
• Ferns have:
– Vascular tissue
– Strong roots
– Underground systems
called rhizomes
– Large leaves called
fronds
Pterophyta
• Like wet habitats
• Like shady areas
• In tropical areas can
grow as large as small
trees
Life cycle of the fern 
• Ferns and other
vascular plants have a
life cycle in which the
diploid sporophyte is
the dominant stage.
• Fern sporophytes
develop haploid spores
on the underside of
their fronds in tiny
containers called
sporangia.(also see
page 562).
• Sporangia are
grouped
together in
tiny clusters
called sori
(singular,
sorum).
• When the spores
germinate, they develop
into haploid
gametophytes.
• The gametophyte first
grows a set of root-like
rhizoids.
• It then flattens into a thin,
heart-shaped green
structure that is the
mature gametophyte.
• The gametophyte contains both egg (in the
archaegonia) and sperm (in the antheridia).
• Once the egg is fertilized by the sperm, it
grows into a sporophyte.
• See the diagram on page 562 in your text for
the life cycle of the fern.
•
•
•
•
Answer these questions from page 559
1. How is water essential in the life cycle of a
bryophyte?
3. What is the relationship between the
gametophye and the sporophyte in mosses?
4. What is an archegonium? An antheridium?
How are these structures important in the life
cycle of a moss?
5. What characteristic of bryophytes is
responsible for their small size?