Transcript Chapter 29-The Importance of Plants

Chapter 29: The Importance of Plants
29-1 Plants and People
29-2 Plants and the Environment
29-1 Plants and People
I. Botany
• Branch of biology dealing with the 350,000 species of plants.
II. Plants as Food
• Fewer than twenty plant species provide more than 90 percent of our
food supply; 10,000 plant species have shown value as foods.
(1) Agriculture (11,000 years ago)
• Farmers propagated plants that had valuable traits, including high fruit
yield.
(2) Cultivars (i.e., cultivate-variety)
• Crops that evolved through artificial selection (e.g., Thompson Seedless
Grapes, MacIntosh Apples, Valencia Oranges, Yoshiro Cherries.)
III. Food Crops
• Classified by use and by family but not phylogeny.
Description
Examples
grasses with edible dry fruit
rice, wheat, corn, oats, rye
known as grains
roots or underground
stems rich in
carbohydrates
potato, sweet potato, taro
members of the pea family
with protein-rich seeds in
pods
soybean, peanut, bean,
pea, alfalfa
the part of a flowering plant apple, banana, grape,
containing seeds
orange, pineapple
leaves, stems, seeds, and
roots of soft plants
spinach, sweet corn,
tomato, turnip
a one-seed fruit with a hard peanut, walnut, pecan,
outer layer
coconut, almond
plant parts other than the
leaf that add taste to food
pepper, vanilla, ginger
plant leaves that add taste
to food
sage, dill, basil, mint,
oregano
Category
Description
Examples
Cereals
grasses with edible dry fruit
rice, wheat, corn, oats, rye
known as grains
Root crops
roots or underground
stems rich in
carbohydrates
potato, sweet potato, taro
Legumes
members of the pea family
with protein-rich seeds in
pods
soybean, peanut, bean,
pea, alfalfa
Fruits
the part of a flowering plant apple, banana, grape,
containing seeds
orange, pineapple
Vegetables
leaves, stems, seeds, and
roots of soft plants
Nuts
a one-seed fruit with a hard peanut, walnut, pecan,
outer layer
coconut, almond
Spices
plant parts other than the
leaf that add taste to food
pepper, vanilla, ginger
Herbs
plant leaves that add taste
to food
sage, dill, basil, mint,
oregano
spinach, sweet corn,
tomato, turnip
(A) Cereals (provide 50% of the worldwide calories in the human diet)
• Grasses containing grains, the edible, dry fruits of a cereal.
• Rice, wheat, corn, oats, sorghum, rye and millet are all examples of cereal
crops.
(B) Root Crops
• Roots or underground stems that are rich in carbohydrates.
• Potatoes, beets, carrots, radishes, rutabagas, turnips, and cassava
(tapioca).
(C) Legumes (mutualism with the N-fixing bacteria Rhizobum in the
roots)
• Members of the pea family and bear protein-rich seeds in pods.
• Soybean, Alfalfa, Peanuts, and Clover.
(D) Fruits, Vegetables, and Nuts
• A group of classifiable plant products consumed for nutrition.
(1) Fruits
• Part of the flowering plant that usually contains the seeds. (e.g.,
tomatoes, green beans, squash, etc…)
(2) Vegetables
• Derived from the leaves, stems, seeds, and roots of non-woody plants.
(e.g., spinach, celery, lettuce, carrots, etc…)
(3) Nuts
• Hard outer layer and a dry, one-seed fruit. (e.g., almonds, walnuts,
pecans, hazelnuts, cashews, etc..)
Assortment of true and false nuts: A. Hazelnut (Corylus americana), B. Pecan (Carya illinoensis), C.
Peanut (Arachis hypogea), D. Macadamia Nut (Macadamia integrifolia), E. Almond (Prunus
amygdalus), F. Brazil Nut (Bertholletia excelsa), G. Chestnut (Castanea dentata), H. Kukui Nut
(Aleurites molucanna), I. Water Chestnut (Trapa bicornis), J. Walnut (Juglans regia). [True nuts: A. &
G.; Drupes: B., D., E., H., I. & J.; Seeds: F.; Legumes: C. Note: The pecan (B) and walnut (J) are also
considered to be a true nuts by some botanists.]
(E) Spices, Herbs, and Flavorings
• Spices are derived from non-leaf tropical plant parts and herbs are
usually derived from leaves and can be temperate; flavorings like chocolate
are placed in a separate category.
(1) Quinine (a type of flavor)
• Flavor derived from the bark of the cinchona tree used to make tonic
water and also treat malaria.
(F) Food Production
• Massive food shortages have not occurred due to increased use of
irrigation, fertilizers, pesticides, and improved cultivars.
(1) Fertilizers
• Supply plants with essential minerals and nutrients like nitrogen and
phosphorous.
(2) Pesticides
• Chemicals designed to prevent competition for limited resources,
typically with herbivorous insects.
IV. Nonfood Uses of Plants
• Include industrial, recreational, atmospheric, and medicinal forms of
utilitarian value.
(A) Medicines
• Plants were our first medicines, and early plant biologists or botanists
like Carolous Linnaeus, were often medical doctors.
(1) Aspirin (acetylsalicylic acid)
• Derived from the bark of the white willow tree (Salix genus)
(B) Clothing and Fabric Dyes
• Cotton (hairs attached to seed of cotton plant), Linen (flax plant), and
artificial fabrics (rayon)—processed wood fibers, tannin (many trees)
used to toughen leather products.
• Dyes derived from coal, which is partially the result of fossilized plant
remains.
(C) Fuels (for heat, electricity, and machine fuel)
• Fossil fuels (developed countries) and wood materials (underdeveloped
countries)
(1) Gasohol
• Grains can be fermented into alcohol and mixed with gasoline; about 10%
alcohol, can be used as a cost effective alternative to full gasoline.
(D) Other Uses of Plants
• Environment—Prevent soil erosion, reduce noise pollution, provide
habitats for life, act as windbreaks, provide shade for housing.
• Inspirational—the “cocklebur plant” provided an idea for Velcro when
the inventor had a burr caught in his clothing.
29-2 Plants and the Environment
I. Plant Ecology (interactions between plants and the environment)
• Plants play a major role in the abiotic cycling of Earth’s water, oxygen,
carbon dioxide, and inorganic nutrients (and also biotic roles).
II. Plant-Animal Interactions
• Plants have evolved roles at prey, predators, and mutualistic symbionts.
• Ex: Some orchid species have evolved to resemble their wasp or bee
pollinators.
III. Plant-Microbe Interactions (mutualism and parasitism)
• Mutualisms between nitrogen-fixing bacteria (legumes) and mycorrhizal
fungi (most terrestrial plant species)
IV. Protecting Native Plants
• Human activity has changed natural plant populations by introducing
foreign plant species, diseases, and animals.
(1) Weeds (e.g., water hyacinth, kudzu, crabgrass, and dandelion)
• Undesirable plants that often crowd out crop plants or native plant
species.
• Water hyacinths float on lakes and rivers, growing so rapidly and densely
that they impede boats and shade underwater plants.
• The introduction of a fungal disease in 1904, chestnut blight, virtually
wiped out the American chestnut as a dominant forest tree in eastern USA
V. Harmful Plants
• Tobacco, cocaine, opium, poison ivy, poinsettia sap, holly berries, and
American mistletoe.
(1) Hay Fever (plant allergies of small, drab flowers that are wind-pollinated)
• Allergic reaction that results from pollen release of three seasons:
(1) Early Spring—Oak, Ash, Birch and Sycamore Pollen
(2) Late Spring/Early Summer—Grasses Pollen
(3) Late Summer/Early Fall—Ragweed Pollen
Revisiting Interdependence of Organisms
• Plants provide people with food, medicines, commercial materials, and
oxygen.
Assessing Prior Knowledge
• Describe several plant adaptations that have been selected for by nature.
• Explain how human activity may have influenced the evolution of several
plant species.