Download Exercise 1 A BRIEF SURVEY OF MEMBERS OF THE PLANT

Exercise 1
A BRIEF SURVEY OF MEMBERS OF THE PLANT KINGDOM
& OTHER PHOTOSYNTHETIC ORGANISMS
According to E. O. Wilson in his book The Diversity of Life over 248,000 different species of living plants
are presently known. Most of these plants possess green pigments (i.e., chlorophyll) and manufacture their own
food using the raw materials from their environment and the energy from sunlight through a process called
photosynthesis. Plants, by and large, are autotrophs (self feeders), whereas animals, fungi, and most bacteria are
heterotrophs (other feeders) and obtain their food from living or non-living organic matter. Other photosynthetic
organisms, not currently classified in the plant kingdom, include single-celled prokaryotes (e.g., cyanobacteria or the
“blue-green algae”), eukaroyotic single-celled algae (e.g., some green algae, diatoms, dinoflagellates, and desmids),
eukaroyotic colonial algae (e.g., Volvox), eukaryotic filamentous algae (e.g., some green algae, such as Spirogyra
and Ulothrix), and multicellular algae (e.g., some green algae such as Ulva or sea lettuce, as well as red and brown
algae). This exercise is an introduction to the different groups within the plant kingdom and other autotrophic
organisms. Students should observe all demonstrations as directed by the laboratory instructor.
For additional information, refer to the figures and text given in the
PRELUDE section that appears near the beginning of the photographic
atlas for the hierarchal classification scheme used for living organisms.
I. BACTERIA DOMAIN: PHOTOSYNTHETIC BACTERIA
Bacterial species are prokaryotes (i.e., lacking a true membrane bound nucleus within the cell) that are
microscopic in size, and found all around the world. Some members of the Bacteria Domain are heterotrophic
(other feeders) and therefore are incapable of making their own food. Many of these bacteria are decomposers,
while others are pathogenic or disease causing. Other members of this domain are autotrophs. These are
represented by the photosynthetic bacteria, which are divided into three categories that include the Cyanobacteria
or “blue-green algae” (e.g., Anabaena, Oscillatoria, Nostoc), Green bacteria (e.g., Chlorobium), and Purple
bacteria (e.g., Rhodospirillum).
Note the specimens of living and/or preserved cyanobacteria that are
available at Station I in the laboratory. Take a few moments to
examine these under the microscope according to the directions given
to you by the laboratory instructor. Compare what you see in lab with
the figures given in the photographic atlas (i.e., Figures 2.9, 2.15, 1.16,
2.17, 2.19, 2.20, 2.21; Table 2.1).
II. EUKAROTA DOMAIN: KINGDOM PROTISTA - THE ALGAE
Like other members of the Eukarota Domain, cells of these organisms possess a true nucleus and other
membrane bound organelles, including chloroplasts, within the living cell. Algae are members of the Kingdom
Protista. Algae grow mainly in water throughout the world and include such forms as the pond scums, kelps, and
sea weeds. Many are microscopic, while some marine forms reach lengths of one hundred feet of more.
Photosynthetic and accessory pigments vary among these diverse organisms causing different groups to differ in hue
and color (e.g., yellow, brown, red, and green). Algae furnish aquatic animals with food and produce over one-half
of the world's oxygen supply. Some are consumed as human food, while others are beneficial as emulsifiers and
stabilizers in frozen foods and dairy products. Certain algae are useful in producing a laboratory culture medium
(agar) for microorganisms. Some are also used for filtering, as abrasives in toothpaste, and the production of
explosives. Red tides are caused by certain algae.
Note the specimens of living and/or preserved algae that are available
at Station II in the laboratory. Take a few moments to examine these
under the microscope according to the directions given to you by the
laboratory instructor. Compare what you see in lab with the figures
given in the photographic atlas (i.e., Figure 3.3, 3.6, 3.25, 3.26, 3.27,
4.2, 4.9, 4.30, 4.32, 4.38, 4.41, 4.42, 4.48, 4.49, 4.50, 4.51, 4.65, 4.66,
4.69).
NOTE: THE FOLLOWING PLANT GROUPS ARE ALL
MEMBERS OF THE EUKAROTA DOMAIN: KINGDOM
PLANTAE - THE MULTICELLULAR PLANTS
III. LIVERWORTS AND MOSSES
These are small land plants lacking conducting tissues. They grow mainly in moist habitats and are
important for soil conditioning, water retention, and as ground cover. Most liverworts grow close to the substrate
and possess a flat body called a thallus. Mosses grow more erect and possess a plant body called a gametophore.
Note the specimens of mosses and liverworts that are available at
Station III in the laboratory. Compare what you see in lab with the
figures given in the photographic atlas (i.e., Figures 6.1, 6.24, 6.26,
6.30, 6.31, 6.33).
Note: The following plant groups are also land plants, possess an
embryo, are multicellular and, in addition, possess conducting tissue that
enables increased growth. Most have true roots, stems, and leaves.
IV. CLUB MOSSES
Club mosses are seedless vascular plants that are somewhat larger than liverworts and mosses and are
mainly found in wet areas. They are good for ground cover, for terrariums, and also as miniature pines (as in
Christmas ornaments).
Note the living specimen of whisk fern or Psilotum and other available
club mosses on display at Station IV in the laboratory. Compare what
you see in lab with the figures given in the photographic atlas (i.e.,
Figures 7.3, 7.12, 7.19).
V. HORSETAILS
These seedless vascular plants constitute a small group of plants considered by many as living fossils.
They grow erect to heights of 5 or 6 feet and can grow in dry or wet areas. Some fossil forms of horsetails are tree
size. Horsetails have large amounts of silica in certain cells and were used by early settlers to clean and scour pots
and pans. Hence, they are sometimes called scouring rushes.
Note the living specimen of horsetail or Equisetum on display at
Station V in the laboratory. Compare what you see in lab with the
figures given in the photographic atlas (i.e., Figures 7.26, 7.27).
VI. FERNS
Although ferns are most abundant in tropical regions, they are also found in temperate areas. Some are tree
forms reaching heights of 60 feet. Ferns reproduce by spores, which originate in brownish structures on the
underside or tips of leaves (fronds). The plants are often grown in greenhouses and gardens for the beauty of their
foliage. Some ferns are used for human food, and one kind furnishes a drug useful in expelling tapeworms. A few
ferns are considered poisonous.
Note the living specimens of ferns on display at Station VI in the
laboratory. Compare what you see in lab with the figures given in the
photographic atlas (i.e., Figures 7.37, 7.38, 7.44, 7.45, 7.56).
Note: The following plant groups, in addition to growing on
land, having an embryo, being multicellular, and possessing
conducting tissue, also reproduce by seeds.
VII. GYMNOSPERMS - “naked seed”
This group includes pines, firs, spruce, bald cypress, cedar, and ginkgo. Seeds are borne in cones and
leaves are mainly small, needle-like, or awl shaped (except Ginkgo). The group contains important trees for lumbar,
fuel, resins, pulpwood, and Christmas trees. The Douglas fir is the most important lumber tree in the United States.
Note the living specimens of gymnosperms on display at Station VII in
the laboratory. Compare what you see in lab with the figures given in
the photographic atlas (i.e., Figures 8.2, 8.3, 8.19, 8.20, 8.21, 8.22,
8.34, 8.44, 8.61, 8.77, 8.80 ).
VIII. ANGIOSPERMS - “vessel seed”
All angiosperms possess flowers and bear seeds in an ovary, which later develops into a fruit. This is the
largest and most important of all plant groups today. They are important as food, for medicines, fabrics, and for
lumber. The trees are considered hardwoods with oaks being the most important lumber trees of the Angiosperms in
the United States.
Note the living specimens of flowering plants or angiosperms on display
at Station VIII in the laboratory. Compare what you see in lab with
the figures given in the photographic atlas (i.e., Figures 9.1, 9.2, 9.4,
9.110).
CAMPUS FIELD TRIP
I. KEY TO THE CAMPUS TREES
Many kinds of plants occur on a university campus and some of the more prominent plants are trees. This
laboratory exercise is a quick way to identify some of the common trees on your campus. This method of
identification is by following a process of elimination using a dichotomous key. The reader is always given two
choices and the choice that matches the plant being observed is the one to select. The reader will be referred to an
alphabetical choice such as A, S, or U. The letter choice may be replaced occasionally by a plant name (hopefully
correct) which means the reader has identified the plant. The common name for the kind of plant is given first and
the scientific genus is second. For example: Teeth not bristle-tipped...Elm (Ulmus).
A. Leaves needle-like or scale-like.....B
B. Leaves in fascicles (clusters).....C
C. Five or less leaves per fascicle (cluster).....Pine (Pinus)
C. More than five leaves per fascicle (cluster).....Cedar (Cedrus)
B. Leaves not in fascicles (clusters).....D
D. Needle-like leaves present.....Spruce (Picea)
D. Needle-like leaves absent, leaves scale-like.....Eastern Red Cedar (Juniperus)
A. Leaves not needle-like or scale-like, but broad and flat.....E
E. Fan-shaped leaves present, venation open dichotomous type.....Ginkgo or Maiden Hair Tree (Ginkgo)
E. Fan-shaped leaves absent, venation net type.....F
F. Leaves with whorled arrangement.....Catalpa (Catalpa)
F. Leaves not whorled, alternate, opposite, etc.....G
G. Plants with opposite leaves.....H
H. Leaves pinnately compound.....Ash (Fraxinus)
H. Leaves not pinnately compound, simple.....I
I. Margins of leaves entire (smooth).....Dogwood (Cornus)
I. Margins of leaves not entire, lobed.....Maple (Acer)
G. Plants without opposite leaves, alternate.....J
J. Leaves pinnately compound.....K
K. Bipinnately compound leaves present.....Mimosa (Albizzia)
K. Pinnately compound leaves present.....Hickory and Pecan (Carya)
J. Leaves not pinnately compound, simple.....L
L. Buds clustered at tip of stem.....Oak (Quercus)
L. Buds not clustered at tip of stem, scattered.....M
M. Margin of leaves entire (smooth).....N
N. Leaves heart-shaped, thin.....Redbud (Cercis)
N. Leaves not heart-shaped, thick.....Magnolia (Magnolia)
M. Margin of leaves not smooth, toothed, lobed, etc.....O
O. Leaves with numerous small teeth on margins.....P
P. Teeth on margins rounded.....Mulberry (Morus)
P. Teeth on margins not rounded.....Q
Q. Leaves narrowed at the base.....R
R. Teeth bristle-tipped.....Chestnut (Castanea)
R. Teeth not bristle-tipped.....Elm (Ulmus)
Q. Leaves not narrowed at the base.....S
S. Lobes present on leaves.....Sweetgum (Liquidambar)
S. Lobes absent on leaves.....Linden or Basswood (Tilia)
O. Leaves lacking small teeth, or teeth large, or leaves lobed.....T
T. Lobes present on leaves.....Sycamore (Platanus)
T. Lobes absent on leaves.....Cottonwood, Poplar (Populus)