Download Plant Diversity Stations Activity

Plant Taxonomy Stations Lab
Station 1: Bryophyta - Mosses
Restricted to damp environments, mosses are familiar to those of us
in the rainy NW! Mosses (Phylum Bryophyta) do not have vascular
tissue – no veins! They absorb moisture from the wet ground like a
sponge.
The green carpet of moss we observe consists of leafy haploid
individuals.
 Some leafy little moss plants make sperm, and some, eggs.
 With rain, sperm cells are splashed to the eggs -- another reason
why bryophytes are restricted to damp habitats.
 The diploid zygotes, embedded at the tops of the leaves of the
moss plants, are not found within seeds – mosses don't have
seeds! The vulnerable zygotes have cell division and grow up
into little stalks.
 At the top of each stalk is a capsule where meiosis produces
spores.
 The spores fall to the wet ground and grow up into leafy
haploid moss plants…
Take a look at the moss plants here! Do you see both haploid
Plant Taxonomy Stations Lab
and diploid individuals? Make a little sketch so you know which
is which.
Plant Taxonomy Stations Lab
Station 2: Bryophyta – Liverworts
The flat, fleshy plants here are moss cousins called liverworts: liver,
because their leaves look vaguely like the lobes of a human liver,
and wort for herb.
Like mosses, liverworts are considered to be primitive plants. They
lack veins (so they soak up moisture from the wet ground like a
sponge) and, like mosses, the liverwort life cycle features swimming
sperm and no seeds. As a result liverworts are only found in very
moist places.
Check it out: The liverworts here may have little "cups" on
their surfaces called gemmae ("GEM mee") cups. Inside
gemmae cups are tiny asexually-produced plantlets. When rain
splashes on the gemmae cups, the plantlets fall to the soil and
grow.
(As mentioned above, liverworts also reproduce sexually.)
Plant Taxonomy Stations Lab
Station 3: Filicinophyta
Ferns – you know 'em! Fern fronds have veins. They have vascular
tissue. As a result, filicinophytes are taller than bryophytes.
Ever wondered what the “dots” on
the undersides of fern fronds are?
They’re called sori. Each sorus is a
cluster of sporangia (sporeSorus
producing structures).
Do any of the fern fronds at this station have sori?
The big leafy fern we know is diploid.
 Within sori, haploid fern spores are made by meiosis.
 Spores fall to the ground and grow up into tiny, flat, heartshaped haploid ferns that we never see…
 The haploid fern plants make sperm and egg cells by mitosis.
 A sperm cell swims to and fertilizes an egg, producing a zygote.
But that zygote is not enclosed in a seed. Ferns are seedless.
 The zygote quickly grows up into the leafy, diploid fern we
see….
Because of its swimming sperm and seedless zygotes,
ferns are restricted to moist habitats.
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Plant Taxonomy Stations Lab
Are you familiar with horsetails, genus Equisetum? They are cousins of
ferns. Check out the pictures and/or specimens here: Does the name
“Horsetail” make sense? Fun fact: Horsetails have a gritty texture and
pioneers used them to scrub their pots and pans.
Plant Taxonomy Stations Lab
Station 4: Coniferophyta
Washington is the Evergreen State because of our cone-bearing trees,
or conifers. Conifers belong to Phylum Coniferophyta and include
firs, pines, spruces, hemlocks, cedars and redwoods. There are only
about 550 species of conifers in the entire world!
Clearly, given how tall they can grow, conifers have vascular tissue!
Conifers do not require free-standing water to complete their life
cycles as bryophytes and filicinophytes do. The conifer life cycle
features an adaptation to protect the zygote: seeds! Seeds form on
the scales of a (female) cone, rather than enclosed in the ovaries of
flowers. Thus conifers are sometimes called “naked seed plants”.
Check out the picture of a cross-section of a pine needle here.
See its (1) vascular tissue? (2) photosynthetic mesophyll tissue?
(3) epidermis and thick cuticle? Needles are an adaptation for
low-water conditions (such as hot summers and cold winters in
which water is locked up as ice/snow).
(FYI: the 2 big tubes in the mesophyll are resin glands.)
Plant Taxonomy Stations Lab
Station 5: Angiospermophyta
Plants in Phylum Angiospermophyta have “covered seeds.” The
ovary of a flower encloses the embryo and its food supply (both
within a protective seed coat). Some sources refer to Phylum
Angiospermophyta as Anthophyta.
Angiosperms or flowering plants are the dominant plants on Earth
today. Botanists estimate that there are more species of angiosperms
than there are all other kinds of plants combined!
There are two Classes of angiosperms, monocots and dicots.
Using only their visible characteristics (e.g. please don't destroy
the plants!!), classify the potted plants at this station as monocots
or dicots.
You will notice that leaf venation is one way to distinguish
monocots and dicots. Angiosperms have vascular tissue.
Plant Taxonomy Stations Lab
Station 6: Xerophyte Angiosperms
Examine the angiosperms here (living or pictures). Dry-adapted
angiosperms are called xerophytes. (Xero is Greek for “dry.”) Cacti
and euphorbs are common examples of xerophytes.
Brainstorm a list of different structural adaptations of
xerophytes. Consider leaf size/shape, root size, location of
stomata, possession of special tissues, and other morphological
or physiological adaptations enabling them to thrive in dry
conditions. Aim for 5-6 items on your list! Then, see the KEY:
KEY:
Some desert plants avoid drought by riding out a drought as seeds or tubers, and then
starting to grow when water becomes available.
Some xerophytes (e.g. Ocotillo) shed their leaves when water is scarce, and then sprout a
new set when there is sufficient water.
Some xerophytes are able to more efficiently extract water from the soil by having
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very salty cell cytoplasm and therefore a very low Ψ in the roots
very deep roots to go after deep sources of water
very shallow roots which pick up the slightest rainfall immediately.
Some have special leaf/stem features to minimize transpirational water loss, like:
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Thick, leathery cuticles (e.g. Aloe)
Fewer stomata (e.g. Cactus)
Stomata underneath "hairs" (e.g. Edelweiss) or within pits or grooves (e.g.
Ammophila), all of which create a humid microclimate
Water stored in stems and tubers (Baobab), and featuring spines or toxins to protect
that same tissue from herbivores.
Some xerophytes have a different type of photosynthesis that allows them to open their
stomata for carbon fixation at night, then complete the rest of photosynthesis during the
day with their stomata closed.
Plant Taxonomy Stations Lab
Source: Tomkins, S. and J. Hewitson. “Science and Plants for Schools (SAPS) Questions and Answer Archive.” Cambridge
University. Updated: 2/25/09. Date accessed: 10/16/09. http://wwwsaps.plantsci.cam.ac.uk/records/rec254.htm
Plant Taxonomy Stations Lab
Station 7: Jurassic Plant!
Study this picture of the fossil Jurassic angiosperm Archaefructus.
It is enlarged about 6 times in the picture. (So, how big was it in
real life??)
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Read the text below: (adapted from “Fossil Discovery: World’s Oldest Flowering
Plant?,” The Seattle Times, 27 Nov.’98.)
This 142-million year old fossil was unearthed from the
lower Yixian Formation near Beipiao in northeast China.
The Yixian Formation was once on the bottom of a lake
that was periodically showered with volcanic ash.
Villagers digging in the fossil beds have unearthed
dinosaurs, insects, birds, and other plants, but this is the
first time a flowering plant has been found.
This ancient plant lacks the petals and shape most people
associate with flowers. “It doesn’t have any beautiful or
showy flowers, but it is a flowering plant… Some of the
leaves are closed, like peapods, and contain seeds. This
makes them carpels. Carpels define the angiosperms.”
Check out the diagram showing carpel evolution from a leaf.
Plant Taxonomy Stations Lab
Station 8 or 9: Plant Diversity
Copy this learning target onto the last page of your yellow Plants
Learning Targets packet:
"5.5.3 Distinguish between the following phyla of plants using simple
external recognition features: bryophyta, filicinophyta, coniferophyta,
and angiospermophyta."
Having visited at least stations 1-5, you can do this! How about
making a chart like this in your journal:
Plant Phylum
Bryophyta
Filicinophyta
Coniferophyta
Angiosphermophyta
External recognition features
Restricted
Other
Veins? Seeds? to moist Size? cool
places?
stuff