Ideas for Teaching
Ideas for Teaching Botanical Biodiversity
Modern scientific thought does not require that scientific principles be used for everything in life, although some scientists recommend it. The scientific method is intended for dealing with things of nature, and the principles inherent in art, philosophy and religion are to be used for dealing with problems in art, philosophy and religion. There is overlap, of course, and in those cases scientists should use scientific methods, others their own methods.
Some naturalistic philosophers:
Democritus, 460-360 B.C. A materialist, he held that the world was made up of tiny particles. By constant motions they combine to make the universe. The nature of things can be discovered only by thought, for sense perceptions are confusing.
Epicurus, 342-270 B.C. Said that intellectual pleasure or serenity is the only good in life.
Lucretius, 95-54 B.C. Said that the universe came into being through the workings of natural laws in the combining of atoms (tiny particles).
Francis Bacon 1561-1626. Popularized the inductive or inferential method of modern science, which reasons from particulars to the general.
John Locke, 1632-1704. Founder of British Empiricism; Empiricism states that that all knowledge is derived from experience - as opposed to Rationalism, which, though Rationalism emphasized that reason should be the basis of human knowledge, often accepts reasoning from "basic premises", which are denied by Empiricism. Locke said that the mind at birth was a blank upon which human experience inscribes all knowledge.
Enlightenment: train of thought in the 18th Century that was rationalist, liberal, humanitarian and scientific. People associated with the Enlightenment include: Diderot, Voltaire, Montesquieu, Rousseau, Hume, Paine, Kant, and many thinkers involved in the American and French revolutions.
David Hume, 1711-1776. A skeptic, he rejected the possibility of certain knowledge; he fell back on common sense and faith.
Herbert Spencer, 1820-1903. Used the doctrine of evolution as a unifying principle in understanding all phenomena. He did not deal with the unknowable, such as metaphysics or certain scientific concepts, but dealt only with those things that can be compared with or related to other things.
METHODS OF SCIENCE
(1) Hypotheses should be falsifiable, that is, they should be presented in such a way that they can be tested. They are more acceptable as explanations to the extent that they survive repeated attempts to prove them false. Scientific hypotheses are not expected to be proven true; they are inferences that simply have not yet been proved false though not through want of trying.
(2) Observations, including results of experiments, must be reproducible by other researchers.
(3) Scientific theories and results of experiments must be openly published in sufficient detail to be testable.
(4) Scientific theories and results of experiments must be free of obvious internal contradictions.
(5) The scientist must be willing to follow the data where it leads, rather than bending the evidence to fit some preconceived rationale.
(6) Scientific hypotheses should not include explanations that are unique to a particular event or factors that are not part of observed nature.
As part of a biology curriculum, botany is important because:
(1) Plants provide, directly or indirectly, all our food, oxygen, fossil fuels, clothing, paper and much of our shelter.
(2) They are important in health maintenance through providing medicines and healthy diet.
(3) They will be important in manned space exploration.
(4) They contribute to a high-quality life by in providing psychological well-being, art, gardening, and pollution control.
(5) In biology teaching they provide a partial solution to the animal dissection controversy, since many major biological principles can be demonstrated with plant experiments.
Classification: Assigning specimens to groups in a hierarchy of ranks distinguished by structure, origin or other characteristics.
Taxonomy: The science dealing with principles and procedures of classification. Taxonomy usually implies the most basic activities of classification, such as obeying rules for naming groups, methods of sorting species and actually doing so, etc., and usually does not include biogeography (the study of distribution of organisms, especially as to migration patterns) or phylogenetics (analysis of evolutionary relationships).
Systematics: Essentially the same as taxonomy, but a more general term in that it usually includes biogeography (where things grow and why) and phylogenetics (presumed family trees).
IDEAS FOR PROJECTS:
Field collection of seeds, leaves, flowers, photos. Best to have complete plant. Collect only those groups for which you have good identification manuals, e.g. native tree leaves, common wildflowers, garden plants.
Different groups of plants require different preservation techniques. See "How to Know the ...." series of spiral-bound books in Gift Shop for instructions.
Economic Botany. Identify the plant and the part of the world from which everyday objects come: cotton, chairs, baseball bats, cocoa, penicillin, etc.
Supermarket Botany. Identify plant and plant parts of common and tropical vegetables and processed foods made from plants.
Grow plants that are commonly cultivated and also grow plants that are used by native peoples and pioneers for the same thing. This will demonstrate the utility of preserving "biological diversity" because if a commonly cultivated species disappears because of disease or insect pests, then there is another species to fall back on. What would happen if corn were to die off because of a virulent smut? Wheat? Rice? Plant breeders can make good producers from wild plants what have only a potential as foods, etc. What about plants from which products can be made that are otherwise only made from petroleum?
Write commercial associations and industry lobbying groups in Washington, DC (see Washington phone book for addresses), for information and demonstration kits of plant productions (e.g. cotton, timber, cocoa, beer, etc.).
Photograph different kinds of habitats and list all the kinds of organisms the different habitats support. Describe how the habitats differ: minerals, soils, water, sun/shade, people pressure, competition, pesticides, etc.
Vectors: observe several different kinds of flowers to see what pollinators choose to visit them. Write down flower color, odor (sweet or fruity), time of day it opens, adaptations to wind pollination or insect pollination.
Beetle-pollinated flowers: Magnolias, some lilies, wild roses, California Poppies. Also dogwoods, spiraeas, many of carrot-family, Skunk Cabbage. Beetles - highly developed sense of smell, poorer sight: therefore beetle-pollinated flowers are usually white or dull but have strong odors (fruity, spicy or fermentaceous as opposed to sweet). Nectar is secreted or if beetles chew the flower parts, the seeds are concealed beneath the floral chamber.
Bee, Wasp and Fly pollination: nectar and pollen taken. Bees see colors and outlines well, and can sense odors, cannot see red but can see ultraviolet as a distinct color. Many floral adaptations to coat hairy bodies with pollen. Bee flowers are not pure red. Orchids of genus Ophrys have flowers similar to female bees (pseudocopulation).
Moths and Butterfly pollination: Like bee pollination but many flowers are red or orange since some species of butter flies can see red or orange. Moths are nocturnal, so moth-pollinated flowers are often white and have odor only after sunset (e.g. Nicotiana). Evening primroses with yellow flowers are moth-pollinated.
Bird pollination: Hummingbirds and others in tropics. Lots of nectar but little odor, since sense of smell is poor in birds. Birds have color sense like ours, so bird-pollinated flowers are colorful, mostly red and yellow. Fuchsia, Passion-flower, Encalyptus, Hibiscus, Poinsettia, many cacti, species of banana and orchid families. Flowers are usually large.
Bat pollination: Like bird pollination, but since bats are nocturnal the flowers are usually dull-colored and many open only at night. Odors fermenting or fruity. Flowers borne usually on strong stalks or directly on trunks because bats are comparatively heavy. Organ-pipe cactus.
Wind pollination: flowers have dull colors, relatively odorless, do not produce nectar, petals small or absent, flowers often aggregated and small (some beetle-pollinated flowers are also aggregated and small). Grasses, Birch (catkins), willows, oaks.
Adaptations for seed dispersal include:
Water: water resistant husk, floats, germinates in salty water. Coconut.
Wind: Samaras are winged fruit. Elm, Ash. Maple.
Pappus hairs: Dandelion parachutes. Dust-like fruit. Orchids.
Whole plant: Tumbleweeds scatter seeds.
Explosive dehiscence: Touch-me-not (Impatiens), Witch Hazel.
Animals: Clinging fruit: hooks of Burdock fruits.
Fleshy fruit: seeds survive digestive tract. Cherry. Raspberries. Dogwoods. Grapes. The color of a ripe fruit is a signal that the seeds are mature and the fruit is ready to eat.
GROW PLANTS from supermarket produce: Seeds: avocados, papayas, mangos, grapes, grapefruit, spices, "Eyes": sweet and Irish potatoes, Whole plants (see what kind of flowers are produced): lettuce, cabbage, Brussels sprouts. Where are these plants grown for market and in what part of the world does their wild ancestors grow?
Collect seeds of garden flowers (they are identified in the inexpensive packets you can get in stores).
Visit a nursery: the plants are identified. Also: Visit a botanical garden: South Park Conservatory, Niagara Falls Park School of Horticulture.
Games: Use small or large bags and invent inference games (what's in the bag):
-How many samples must they make to make a good inference about what is in the bag? marbles, paperclips, rubber bands, mixtures of various proportions.
-When is a theory good enough? when it correctly predicts what comes next. It doesn't have to be right, as long as the exception does never comes up, then the theory is servicable to science. All theories are liable to exception.
-How would one invent an explanation game? answering question "how does it work?"
ETHICS AND LEGAL POINTS in collecting. Protected species and protected areas. Get list of "Protected Native Plants" from New York State Dept. Environmental Conservation, 518-457-7370.
The exercise is to teach methods of scientific analysis and synthesis, emphasizing general processes over merely correctly naming plants. The following demonstrate classification techniques in any field and on any collection of objects, nuts and bolts, paper fasteners, nails, etc. This might be good practice and will demonstrate how complex living things are.
A. Collection of actual specimens. Recommended are weeds or tree leaves from non-city areas (cannot identify city or garden plants with field identification guides to wild flowers). Mount pressed and dried specimens with white glue on paper with a label.
a. Analytic methods.
-Describe fully, in a large data table, the physical attributes (morphology) of each specimen. Point out in the table how the specimens differ from each other.
-The label should give the plant's name, if known. Also document each specimen as to place of collection, kind of habitat, date of collection, name of collector, color of flower, height of plant if complete plant not collected (e.g. tree leaves).
b. Synthetic methods.
-Note how each specimen is similar to the others. By noting which specimens are most similar to each other, organize the specimens into groups, and groups of groups (ranks). Make any number of groups of groups at first, but try to end up with four levels of groups of groups.
-Name the most basic groups as species and the next largest groups as genera and the next largest as families and the very largest as divisions or phyla. This can be done with or without recourse to plant identification books. Either use entirely artificial names that you make up for the basic groups (species) and for the groups of groups, or do as much as possible and if a correct name cannot be found in a book, make up a "classroom" name and use that. If you need more ranks, the following is a guideline:
Kingdom - Plantae
Division (Phylum) - Anthophyta
Class - Monocotyledones
Order - Commelinales
Family - Poaceae
Genus - Zea
Species - Zea mays (Corn)
(Zea mays (the actual species) is a taxon, so is Zea (the genus), so is Poaceae (the family), etc. Species is a rank (taxonomic level), so is Genus, etc.)
B. Collection of photographs: Photographs provide a way to document biological diversity of easily identified specimens without actual collection and subsequent negative impact on the environment. This is especially attractive to students since a full description of the specimen is not required in the case of photography. Document each photograph. To what extent can you do analytic and synthetic research using just photographs, and what does this tell you about the value of actual collecting?
This is where the specimen documentation is very important. Map the distribution (make "dot maps") of all groups and groups of groups. What might this tell us about possible reasons for these distributions? Effects of environmental factors and differing habitats (list these), and of vectors (analyze possible effect of different means of seed distribution, e.g. animal fur, stockings, dandelion seeds and acorns). Compare distributions with maps of soil types, rock types, climate differences.
Science offers no explanation about why the universe exists. Questions that cannot be answered through scientific methods are not scientific questions, but are those of art, philosophy or theology. Science has many great triumphs using purely naturalistic explanations about how the world works, and requires purely natural causes for observations for it to work well.
Genetic basis of evolution: recombination of genes. Gregor Mendel, 1822-1884, Austrian scientist and monk, developed principles of heredity from observations of his crossing of varieties of peas in his garden. These principles include: (1) characters are inherited independently from each other, (2) each germ cell receives only one of a pair of alternative factors affecting the characteristic, and (3) some factors are dominant over others. His publication was in an out of the way journal, and was not rediscovered until 1900 when three researchers rediscovered his principles independently, and also discovered his paper. T. H. Morgan in early 1900's showed that some genes are linked because they are on the same chromosome in famous experiments with fruit flies.
THE FOUR PILLARS OF EVOLUTION are:
(1) Natural selection, resulting in fitness and adaptation. Charles Darwin (Origin of species, 1859). He pointed out that variation within a species combined with a struggle for survival could result in new forms, and documented this extensively.
(2) Nature of mutations: evolution cannot go where mutations do not exist. Genetic mutation includes both point and chromosomal rearrangements (deletions, broken parts recombining, doubling. Mutation is the term for heritable changes in an individual, coined by Dutch botanist Hugo DeVries in 1901, during studies of evening primroses. In 1927, Hermann J. Muller in the US found that ionizing radiation causes mutations. Since then, we have found that some chemicals are even more powerful mutagens.
Mutation pressure. Some genes have a particular mutation frequency. It is estimated that, naturally, there occur an average of one mutation at any one gene locus per 200,000 cell divisions.
(3) Population size. Genetic drift in small populations through accidents in survival of particular individuals. Characters of a small population may easily change in isolation. Statistical studies leading to the "founder principle."
(4) Migration and hybridization. Introgression is the introduction of genes into one population from a nearby population that differs genetically. Hybridization may be followed by doubling of chromosomes, followed by loss of single chromosomes.
FITNESS AND ADAPTATION
Fitness: comparative degree of producing offspring that survive to maturity. Differential reproductive rates accompanied by random survival results in most fit species crowding out the less fit.
Adaptation: mutations allow the less fit to better survive to reproductive maturity than others in a particular environment. E.g. wildflowers have enormous reproductive capacity, but trees shade them out and get by with fewer fruit; trees channel energy they could have used for seed production into wood and leaf production.
PHYLOGENETICS, or evolutionary analysis. What relationships between the specimens can be inferred that might be attributed to "descent with modification"? Use of cladistic methods in analysis, i.e. grouping by shared advanced (recently evolved) characters. Identify advanced characteristics and decide on a primitive relative (outgroup) which will have primitive characters that will not be used in deciding relationships. Construct a "tree of life" (a cladogram) showing hypothetical relationships based on shared advanced traits. Several trees may be possible, so select the tree that requires the fewest assumptions of change (the fewest changes that can create a tree including all the items). Scientist's null hypothesis is that as more and more items are sampled, no pattern will emerge (patterns due to randomness will easily change and cancel each other out), so when a pattern emerges repeatedly with more sampling of data, the scientist rejects the null hypothesis in favor on a hypothesis supporting the reality of a pattern in nature.
Can use items other than plants by pretending there are hereditable connections between them, including bottles, nails and screws, etc. Any historical information that is amenable to analysis by clustering shared innovations can use cladistic techniques.
NUMBERS OF DESCRIBED SPECIES - Kingdoms and Divisions
(There are many more species yet undiscovered in the world.)
Kingdom Monera (no nuclear envelope)
Bacteria: 2500 species described, many more undescribed
Cyanobacteria (Blue-green Algae): 7500 species described but probably only 200 free-living forms.
Zygomycetes: 600 species
Ascomycetes: 30,000 described + 25,000 Fungi Imperfecti
Lichens: 20,000 described
Bascidiomycetes: 25,000 described
Kingdom Protista (9+2 flagella, mostly unicellular)
Water Molds: 475 spp.
Cellular Slime Molds: 650
Plasmodial Slime Molds: 450
Diatoms (5600), Golden Algae, Yellow-Green Algae: 6650
Red Algae: 4000
Brown Algae: 1500
Green Algae: 7000
Mosses, Liverworts and Hornworts: 16000
Psilophytes: 2 genera and several spp.
Lycophytes (ground pines): 1000
Gnetophytes (Ephedra and 2 other genera): 70
Flowering Plants: 235,000
Class Monocotyledones - Monocots 65,000
Class Dicotyledones - Dicots 170,000
Tifft Nature Preserve AND
Trampling and other pressures from people and animals (geese).
What would the trampled area look like without being trampled?
How would you test to find out?
• Fence a small area and compare inside and out, or fence a large one and take photos before and after.
• If you made the study a class project, how would you share the results with other schools?
Internet Kids-net, K-12 via Frednet, local community bulletin board systems.
• If you do a study, it is important to follow the scientific method so your explanation of what happened is more probably true than other explanations and your study can be duplicated by others.
Places with plants well-labeled:
Sanctuaries, arboretums, nature centers.
Conservatories, greenhouses, supermarkets, hobby stores.
Habitats and species diversity.
Where are the greatest number of different flowers, fields or woods?
More than 800,000 known plant species.
Of these, 500,000 are flowering plants
3,000 are known to have been used directly as human food.
Only 150 are important enough to have entered world commerce.
Only 12-13 provide 90% of plant calories for humans.
A supermarket is an inexpensive source of plant material for school use.
Edible portions of plants from all over the world are identified and available even during winter.
Other sources of identified plant material for school instruction include greenhouses, arboretums, conservatories, nature centers, and hobby stores that stock dried flowers and other material for arrangements.
Supermarket produce is a good way to demonstrate that different foods come from different areas of the world, and that the different kinds of produce represent distinctive parts of the plant.
Where do our supermarket plants come from?
Nowadays produce can be grown anywhere in the world that the climate is best, but each plant originally evolved in one particular area. A Russian named Vavillov analyzed the origins of important food plants in 1926, and found that most originated in one of four world centers:
Central Asia and India
Highlands of Tropical America.
The most important areas for food plant diversity were mountainous areas. This is a good reason for preserving the present biological diversity of mountainous areas because they are a proven source of plants of importance to humans.
First we must learn the names of the different parts of a typical plant. Many of these parts are sources of food. Example: CHRYSANTHEMUM
Main parts are flower, leaves, stem and roots. Example: LILY
The flower is composed of receptacle, sepals, petals, stamens, and pistil.
The pistil is composed of ovary, style and stigma.
The ovary contains the ovules. When the ovules are fertilized by the pollen from the stamens, the ovules are called "seeds" and the whole pistil is renamed a "fruit." Example: TOMATO.
The leaves are composed of a leafstalk and a blade. Example ROMAINE LETTUCE.
The stem is usually green and vertical, but may also grow underground, in which case it is called a rhizome. When the underground stem is swollen with food, it is called a "tuber." Example: POTATO.
The roots are underground, and have internal structures quite different from stems, the conducting tissues being turned inside out. Example: PARSNIP.
Let's look more closely at some examples.
CAULIFLOWER -Mediterranean region.
BROCCOLI -Mediterranean region.
ARTICHOKE -Mediterranean region.
BROCCOFLOWER -Mediterranean region.
A. COMPOUND FRUIT -several pistils.
AGGREGATE FRUIT -many pistils in one flower.
STRAWBERRY -dry achenes on a receptacle. Europe and America.
RASPBERRY -America, droplets. Raspberry comes off from receptacle, blackberries do not.
MULTIPLE FRUIT -syncarp -many flowers make up one fruit.
BREADFRUIT -southeast Asia.
MULBERRY -central Asia.
PINEAPPLE -northern South America
FIG -syncomium -Mediterranean region. Common have no seeds. Smyrna have seeds.
B. SIMPLE FRUIT -one pistil.
FLESHY FRUIT -ovary wall thickened.
Drupe -inner ovary wall hardened, outer fleshy.
COCONUT -three-sided dry drupe, Malaya.
CHERRY -central Asia.
PLUM -central Asia.
PEACH -southeast Asia.
MANGO -large seed -southern Asia.
BLACK PEPPER -dried unripe in store. India
OLIVE -central Asia. -bitter glucoside destroyed with sodium hydroxide.
PISTACHIO Western Asia.
ALMONDS -Mediterranean region.
Berry -ovary of a single chamber and whole ovary wall fleshy.
GRAPE -Europe and America.
TOMATO -tropical American highlands.
TOMATILLOS or HUSK TOMATOES -Mexico. -America (Physalis).
PRICKLY PEARS (TUNA) -Mexico.
PAPAYA -West Indies or Mexico.
BANANA -southeast Asia. Conservatory has banana trees.
PLANTAIN -India, a modified berry.
PEPPERS (HOT, BELL) -tropical America.
AVOCADO -Mexico, a one-seeded berry.
Pepo or Gourd -berry with receptacle forming a rind.
CHAYOTE -tropical America.
YELLOW SQUASH -tropical American highlands.
ZUCCINI -also pumpkins, America.
MELON -southern Asia.
WATERMELON -tropical Africa.
Hesperidium -berry with leathery rind and ovary in sections, with juice sacs = all citrus fruits.
GRAPEFRUIT -Old World?
LIME -the East Indies.
LEMON -southeast Asia.
Pome -inner wall papery, outer fleshy, receptacle expanded.
APPLE -central Asia.
PEAR -central Asia and Europe.
DRY FRUIT -ovary wall not thickened.
a. DEHISCENT -splitting open by itself.
Legume -simple pistle, two sutures. PEA FAMILY
PEA -central Asia.
BEAN -kidney (including string) and lima beans are from America.
PEANUT -South America
Follicle -simple, one or more sutures but not PEA FAMILY.
MILKWEED -North America
Capsule -compound pistil (many leaves fusing together evolutionarily), one or more sutures.
LILY -North America and Eurasia.
OKRA -tropical Africa.
INDEHISCENT -not self-splitting.
Achene -small fruit, one cavity, one seed.
SUNFLOWER -North America.
Grain -ovary wall fused to seed coat to make a husk (= bran).
CORN -maize -tropical American highlands.
WHEAT -Europe and Asia.
RICE -southeast Asia.
Samara -a winged achene
MAPLE -northern hemisphere.
ASH -northern hemisphere.
Nut—indehiscent dry fruit with a husk.
HAZELNUT (=FILBERT) -Europe and North America.
(seeds come from the inside of a ripened fruit)
PINE NUTS (Pignolia) Southern European pine species.
FLAXSEED -central Asia.
CABBAGE also Kale and Collards. -Mediterranean region.
CELERY Carrot family. -Europe.
FENNEL -Mediterranean (Foeniculum vulgare var. dulce)
RADICCHIO (Red Chicory) -India.
PARSLEY -Mediterranean region.
HERBS like Marjoram, Sage, Dill, Thyme, Basil. Mediterranean region.
BULB -a tight sphere of leaves.
ONION -(unknown in nature) Mediterranean or central Asia.
GARLIC -central Asia.
ASPARAGUS -Mediterranean region.
BRUSSEL SPROUTS -these are buds of a variety of cabbage.
BEAN SPROUTS -Mung bean is from India.
KOHLRABI -a variety of cabbage. Europe.
BROOMCORN -a variety of sorghum. Africa.
CORM -short underground stem.
TUBERS -underground stems swollen with food.
POTATO -tropical American highlands.
SWEET POTATO -southern ones are softer and sweeter and are called YAMS (true yams are tubers from a different family of plants). -tropical America.
GINGER -southeast Asia.
HORSERADISH -Mediterranean region.
PARSNIP -Mediterranean region.
RADISH -central Asia.
BEETS -Mediterranean region.
DAIKON -oriental radish variety.