PLANT PHYLOGENY- THE SEEDLESS PLANTS
DR. SUSAN PETRO
"Whoever does not draw, does not observe." Leonardo da Vinci
"Whoever does not draw, does not observe." Leonardo da Vinci
Laboratory drawings must:
Use your lab manual and A Guide to Biology Lab by Thomas Rust to assist you.
I. Division Hepatophyta - liverworts - read the section on
liverworts
in your lab manual
on pages 166-168 as you do the following drawings. The
adaptations to a terrestrial lifestyle that the Hepatophyta exhibit
in common with all plants is that their gametes, zygotes and
embryos develop protected by tissues of the parent plant and
their spores are non-motile and encased by a very resistant
polymer called sporopollenin.
The gametophyte is the dominant stage of the life cycle in
liverworts and the spore is the dispersal unit.
A. Marchantia
polymorpha
- live specimen
Drawing #1 - Upper surface of thallus (the word thallus refers
to an
undifferentiated plant body i.e. one with no roots stem,
or leaves). Use the dissecting microscope.
B.
Marchantia
sp.
Drawing #2 - Cross section of thallus - prepared slide.
Include
air pores
and rhizoids.
Drawing #3 - Gemma cups (lucite block or living specimen if
available).
Method of asexual reproduction
Drawing #4 - Antheridia (gametangia that produce sperm)
- prepared slide
Drawing #5 - Archegonia (gametangia that produce eggs) -
prepared slide
Drawing #6 - Sporophyte (non-photosynthetic and dependent on the
gametophyte in liverworts) - prepared slide
II. Division Bryophyta - mosses - Read the section on mosses
in
your lab manual on
pages 168-171 (omitting the optional section) as you do
the following drawings. Mosses, unlike liverworts, have a
cuticle and stomata with guard cells. The gametophyte is
still the dominant stage of the life cycle and the spore is still
the dispersal unit.
A. Unidentified
mosses
Drawing #7 - Macroscopic view of a living gametophyte with
attached
sporophyte
B. Polytrichum
sp.
Drawing #8 - Longitudinal section of capsule (which is part of
the
sporophyte) - prepared slide
C. Unidentified
mosses
Drawing #9 - Protonemata. Use the dissecting
microscope
to view the Petri
plate with the moss protonemata. The word protonema
means 'first thread'.
Drawing #10 - Antheridia - prepared slide
Drawing #11 - Archegonia - prepared slide
The word Pteridophyta is often used as a collective term for
the
ferns
(Division Polypodiophyta) and fern allies (Division Lycopodiophyta
and
Division Equisetophyta). In the ferns and fern allies the
sporophyte
becomes
the dominant stage in the life cycle and a vascular system with xylem
and phloem
is now present. The sperm remain flagellated in the Pteridophytes
so these
plants are still dependent on water for fertilization. The spore
remains the
dispersal unit.
III. Division Polypodiophyta - ferns - read the section on
ferns
on pages 171-175
(omitting the optional section) as you do the following
drawings.
A.
Unidentified ferns
Drawing #12 - Observe Petri plate with prothalli (name for the
gametophytes of ferns) under dissecting microscope. If too
immature to have archegonia and antheridia use a prepared
slide to draw a prothallus with archegonia and antheridia
Drawing #13 - Young sporophyte - prepared slide - Use the
dissecting
microscope to view this slide.
B.
Phelebodium aureum - Hare's foot fern
Drawing # 14 - Look at the sori (groups of sporangia) on
the back of
a fern frond under your dissecting microscope. Now
make a slide of the sporangia by scraping several sori
into a drop of water on a slide, crushing with the
razor blade and covering with a cover slip. Draw a
sporangium with spores. There is a nice drawing of
this in your lab manual on page 175.
C. Pteridium sp. - bracken fern
Drawing #15 - Cross section of a rhizome (underground stem) -
prepared slide. Use the dissecting microscope to
view this slide. Note the presence of vascular
bundles containing xylem (the cell walls of xylem
contain lignin) and phloem. Also note the presence
of sclerenchyma, a supporting tissue whose cell walls
contain lignin. There is a nice photograph of this
slide in A Guide to Biology Lab by Thomas Rust.