Exam 4 Flashcards
Seeds components
Protective seed coat, supply of food for embryo, capability of dormancy.
Seed plant advantages
Water and fertilization: drier environments, distances between plants can be greater
Seed anatomy
Smaller gametophytes, heterospory, ovules, and pollen grain
Phylum Pinophyta
Conifers
Phylum Ginkgophyta
Ginkgo
Phylum Cycadophyta
Cycads
Phylum Gnetophyta
Gnetophytes
Gymnosperm
The seed is exposed. Seeds are produced on surface of sporophylls or similar structures instead of enclosed in a fruit like flowering plants. Seed-bearing and pollen-bearing sporophylls often arranged in cones.
Pollen cones produce
pollen grains
Female gametophyte produced
Inside an ovule that contains a nucellus. Reduced in cell number beyond ferns. Does not grow independently but develops within sporophyte structures
Nucellus
enclosed in integument, which becomes the seed coat after fertilization.
Pinophyta
Pines, firs, spruces, cedars. Most economically important phylum. Contains over 100 species.
Ginkgophyta
Has a single living representative. Tree with fan-shaped leaves. Seeds enclosed in fleshy covering.
Cycadophyta
Leaves superficially palmlike
Gnetophyta
Three genera. Wood with vessels; only hardwood of the gymnosperms
Pines are
dominant trees in coniferous forests of Northern Hemisphere. Include the world’s oldest known living organisms, the bristlecone pines.
Pine structure and form
Leaves needlelike and arranged in clusters of two to five leaves. Modifications allow them to survive harsh conditions; hypodermis located below the epidermis, giving one to two extra layers of thick-walled cells; thick cuticle; recessed or sunken stomata; resin canals; mycorrhizal fungi associated with roots of most conifers
Cluster of pine needles
Fascicles
Fascicles
Short shoots, having restricted growth
Resin
Antiseptic, prevents development of fungi, deters insects
Pine wood
Consists entirely of tracheids. softwood.
Softwood
Conifers. thick-walled cells absent
Hardwood
Broadleaf tree (dicot) wood. Thick-walled vessels and fibers present.
Pine reproduction in pollen cones
Male strobili. Consist of papery or membranous scales. Microsporangia in pairs toward bases of scales. Meiosis produces microspores that then develop into pollen grains, which consist of four cells and a pair of air sacs, which add buoyancy in the wind.
Pine reproduction in seed cones
Megaspores in megasporangia within ovules. pair of ovules at bases of seed cone scales. Seed cones larger than pollen cones. Have woody scales with inconspicuous bracts between. Ovule contains a megasporangium containing a nucellus and a single megasporocyte. Sporangia are surrounded by integument, which has a pore called a micropyle. Sporocyte undergoes meiosis, producing four megaspores. Three degenerate. Remaining megaspore develops into female gametophyte with archegonia at micropyle end.
Pine seed cone development
Seed cones take two years to mature. First year, pollen grains catch on sticky pollen drops oozing out of micropyle; pollen grain produces pollen tube that grows through nucellus; two sperms produced in pollen tube; mature male gametophyte is germinated pollen grain with pollen tube and two sperm; sperm have no flagella and no antheridium is formed; megaspore develops. Second year, female gametophyte and archegonium mature; pollen tube arrives at archegonium; one sperm unites with egg, forming zygote; other sperm degenerates. Embryo is then nourished by female gametophyte; integument becomes seed coat
Yew and California nutmeg
Produce ovules singly at tips of shoots. Each ovule at least partially surrounded by cuplike aril (fleshy nucellus).
Junipers
Seed cones fleshy
Southern hemisphere conifer
Merkus pine. Podocarpus - fleshy-coated seeds with large appendage at base
Phylum Ginkgophyta Characteristics
Only one living species. Only exists in cultivation. Notched, broad, fan-shaped leaves on short, slow-growing spurs. No midrib or prominent veins. Hair-like veins branch dichotomously. Deciduous.
Ginkgophyta life cycle
Similar to pines. Dioecious. Seeds enclosed in fleshy seed coat with unpleasant odor
Dioecious
Male and female structures on separate trees
Phylum Cycadophyta characteristics
Slow growing plants of tropics and subtropics. Tall, unbranched trunks. Crown of large, pinnately divided leaves. Life cycle similar to conifers. Pollinated sometimes by beetles. Dioecious. Has pollen and seed strobili.
Phylum Gnetophyta Characteristics
Unique among the gymnosperms in having vessels in the xylem. 3 Genera
Joint firs (Ephedra)
Gnetophytes. Shrubby plants of drier regions of southwestern North America
Gnetum
Gnetophytes. Vine-like plants with broad leaves found in the tropics
Welwitschia
Gnetophyte. Only one species, confined to the deserts of southwestern Africa. Short stem, long taproot, only two straplike leaves that become tattered and split. Dioecious. Has male and female strobili.
Human relevance of conifers
Edible inner park and needles of white pine and seeds of most pines. Masts in sailing vessels. Crates, boxes, matchsticks, furniture. Telephone poles, railroad ties, mine timbers. Turpentine and rosin (both from resin). Fuel. Pulpwood. Construction lumber. Ornamentals. Pharmaceuticals (taxol from yew trees).
Human relevance of other gymnosperms
Ginkgo: seeds for food (after seed coat removal); Ginkgo extracts to increase blood circulation. Ephedra: Mormon tea; drug ephedrine for respiratory problems.
Angiosperms
Flowering plants (vessel seed). Seed enclosed in carpel. Pistil composed of a single carpel or two or more united carpels. Seed develops from ovule within carpel. Ovary becomes a fruit.
Angiosperm Taxonomy
Phylum Magnoliophyta, Classes Magnoliopsida (Dicots; DNA and cladistic evidence suggest that two groups of dicots should be recognized) and Liliopsia (Monocots)
Magnoliophyta Characteristics
Heterosporous. Sporophytes dominant. Female gametophytes wholly enclosed within sporophyte tissue and reduced to only a few cells. At maturity, male gametophytes consist of a germinated pollen grain with three nuclei.
Magnoliophyte development of female gametophyte
Diploid megasporocyte differentiates in ovule. Undergoes meiosis and produces four haploid megaspores. Three degenerate. Remaining cell enlarges and nucleus divides to produce 8 nuclei (without walls). Outer two layers of ovule differentiate into integuments that later become seed coat. Micropyle at one end of ovule. 8 nuclei form two groups, 4 near each end. One nucleus from each group migrates to cell middle and form central cell. Cell walls form around remaining 6 nuclei. Egg and 2 synergids closest to micropyle, 3 antipodals at opposite end (unknown function).
Mature female gametophyte
Large sac containing 8 nuclei and 7 cells. Megagametophyte/embryo sac.
Magnoliophyte development of male gametophyte
Formation takes place in anthers. Four patches corresponding to pollen sacs of microsporocyte cells differentiate in anther. Each microsporocyte undergoes meiosis to produce quartet of haploid microspores, undergoing 3 important changes: divide once by mitosis to form a small generative cell inside the larger tube cell (tube cell nucleus is the vegetative nucleus); members of each quartet of microspores separate; wall becomes 2-layered (outer layer is exine, finely sculpted, contains chemicals that may react with chemicals in stigma). Generative nucleus will later divide to produce 2 sperm
Mature male gametophyte
Germinated pollen grain with vegetative nucleus in tube cell followed by two sperm cell nuclei from generative nucleus.
Pollination
Transfer of pollen grains from anther to stigma. Self-pollination: pollen grains germinate on stigma of same flower. Pollination by insects, wind, water, animals, or gravity.
Fertilization
Union of sperm and egg
Fertilization and development of seed
After pollination, further development of male gametophyte may not take place unless pollen grain is from a different plant of the same species or from a variety different from that of the receiving flower. Pollen tube grows between cells of stigma and style until it reaches ovule micropyle. Vegetative nucleus stays at tips of pollen tube while generative cell lags behind and divides into two sperm. Pollen tube enters female gametophyte, destroying synergid in the process, and discharges sperms.
Double fertilization
One sperm unites with egg, forming zygote, then embryo. Other sperm unites with central cell nuclei, producing triploid endosperm nucleus that develops into endosperm tissue, which becomes extensive part of seed in some monocots. It is absorbed into cotyledons in most dicots. Ovule becomes seed, ovary matures into fruit, integuments harden into seed coats
Endosperm tissue
nutritive tissue for embryo
Other types of female gametophyte development
Female gametophyte can have from 4-16 nuclei or cells at maturity. Endosperm usually 3x, but can be 5x, 9x, or even 15x.
Lily example
All four haploid megaspore nuclei produced from megasporocyte remain functional. Three of nuclei unite forming 3x nucleus and fourth nucleus remains haploid. Results in female gametophyte with four 3x nuclei and four 1x nuclei. One central cell nucleus is 3x and other is 1x. Fertilization results in 5x endosperm nucleus.
Apomixis
Without fusion of gametes but with the normal structures otherwise being involved. Embryo may develop from diploid nutritive cell (2x) or other diploid cell of ovule, instead of from zygote. Results in a vegetatively propagated plant.
Parthenocarpy
Fruits develop from ovaries with unfertilized eggs. Results in seedless fruits. Navel oranges and bananas.
Carpel organization
Simple has a single carpel; compound has multiple carpels fused together
Hypogynous flower
Superior ovary. Ovary produced on top of receptacle. Other flower parts attached around ovary base.
Perigynous flower
Superior ovary. Flower parts attached to corolla tube of fused petals, creating floral tube that is not attached to ovary
Epigynous flower
Inferior ovary. Receptacle or other flower parts fused to ovary and grown up around it. Calyx and corolla appear to be attached to top of ovary.
Complete flower
Has calyx, corolla, stamens, and pistil
Incomplete flower
Corolla or other flower parts mission
Perfect flower
Both stamens and pistil are present
Imperfect flower
Either stamens or pistil are missing
Monoecious imperfect species
Male and female imperfect flowers on same plant
Dioecious imperfect species
Plant bears only male flowers and other plants bear only female flowers.
Bee pollination
Attracted by color. Generally bright, mostly blue or yellow. Often have lines or other distinctive markings, which may function as honey guides to lead bees to nectar. Bees see UV light.
Beetle pollination
Attracted by odor. Strong, yeasty, spicy, or fruity odor. White or dull in color. Beetles do not have keen visual senses. Some do not secrete nectar but furnish pollen or food on petals in special storage cells
Fly pollination
Attracted by odor. Smell like rotten meat. Dull red or brown.
Butterfly and moth pollination
Attracted by fragrance. Often have sweet fragrances. White or yellow for night-flying moths. Sometimes red, often blue, yellow, or orange for butterflies. Nectaries at bases of corolla tubes or spurs for long tongues.
Bird pollination (hummingbirds and sunbirds)
Often bright red or yellow. Little if any odor; birds do not have a keen sense of smell. Large and part of sturdy inflorescence. Copious amounts of nectar, as birds are highly active. Flowers have long floral tubes.
Bat pollination
Primarily in tropics. Open at night when bats are foraging. Dull in color. Large enough for bat to insert head or consist of ball-like large numbers of small flowers.
Orchid flowers
Have all types of pollinators. Some adaptations between orchid flowers and pollinators are extraordinary. Pollen grains produced in little sacs called pollinia with sticky pads at base. Members of Ophrys have modified petal that resembles female bumble bee or wasp. Male bees or wasps attracted to flower. Pollinia deposited on their head
Herbaria
Libraries of dried, pressed plants, algae, and fungi, arranged and labeled. Methods: fungi and bryophytes dried and stored in small packets. Plant press used for vascular plants. Vascular plant specimens mounted on herbarium paper. Specimens stored so retrieval of specimens is easily accomplished.
Harlan’s Regions
Near-eastern region, Chinese region, African continent, South Asia and Pacific Islands, North America, South and Central America
Near-eastern region
Mediterranean, northern Europe. Barley, wheat, peas, lentils, asparagus, beets, carrots, turnips olives, cherries, plums, apricots, apples, onions, garlic, broccoli, lettuce, flax, and pistachios
Chinese Region
Temperate and southern China. Bamboo, peach, walnut, ginger, gourds, camphor, tea, soybean, buckwheat, horseradish, and cucumber
African continent
Mostly Ethiopia and West Africa. Yams, sorghum, okra, sweet melons, coffee, some cotton.
South Asia and Pacific Islands
Sugar can, eggplant, mango, banana, citrus, safflower, nutmeg, clove, cardamum, turmeric, black pepper, coconut, taro, rice, sesame, and onion.
North America
Sunflower, cranberry, blueberry, and tobacco.
South and Central America
Garden beans, corn, peanut, white potato, lima beans, cashew, pineapple, avocado, red pepper, tomato, cotton, cacao (chocolate), sweet potato, pumpkin, squash, rubber, vanilla, and cassava
The Buttercup family
Ranunculacaea. Dicot. Nearly all 1,500 species are herbaceous. Petals vary in number. Numerous stamens. Several to many pistils with superior ovaries. Concentrated in north temperate and arctic regions. Most at least slightly poisonous.
The Laurel family
Lauraceae. Dicot. About 1000 species of tropical evergreen shrubs and trees. No petals, but sepals sometimes petal-like. Stamens in three or four whorls. Anthers open by flaps that lift up. Cinnamon, cassia, camphor, sassafras, trees, sweet bay, avocado.
The Poppy family
Papaveraceae. Dicots. Herbs of temperate and subtropical regions. Numerous stamens, but single pistil. Milky or colored sap. All species produce alkaloidal drugs. Opium poppies: opium - white fluid from capsules; morphine and codeine (heroin); papaverine and noscapine; poppy seeds.
The Mustard Family
Brassicaceae. Dicots. Nearly all 2500 species in temperate and cooler regions of North America. Four flower petals arranged in a cross. Six stamen: 2 short, 4 long. Fruits: siliques or silicles. All produce pungent watery juice. Many cultivated edible plants: cauliflower, brussel sprouts, broccoli, radish, turnip, horseradish, watercress, and rutabaga. Mustard - ground seeds of two species of Brassica
The Rose Family
Rasaceae. Dicots. More than 3000 species of trees, shrubs, and herbs. Flowers have basal parts fused into cup, with petals, sepals, and numerous stamens attached to cup’s rim. Family subdivided into subfamilies on basis of flower structure and fruits. Enormous economic impact: stone fruits - cherries, apricots, peaches, plums; pome fruits - apples, pears; aggregate fruits - strawberries, blackberries, raspberries; garden ornamentals - roses; fragrances; fruits of roses - hips - Vitamin C
The Legume family
Fabaceae. Dicots. Third largest of flowering plant families with 13,000 species. Cosmopolitan (grows globally in many diverse environments). Flowers radial to biradial. Stamens fused into tube around ovary. Fix nitrogen from the air. Fruit is a legume. Many important crop plants: peas, beans, soybeans, peanuts, alfalfa, sweet clover, licorice, and carob.
Spurge family
Euphorbiaceae. In tropical and temperate regions. Several economically important plants. Cassava - staple food in tropical regions. Para rubber tree - crude rubber from latex of inner bark. Stamens and pistils produced in separate flowers, which are often inconspicuous and lack corolla.
Cactus Family
Cactaceae. More than 1500 species native only to Americas in dry, subtropical regions. Leaves reduced in size, often spines. Fleshy stems
Mint Family
3000 species. Unique combination of angular stems that are square in cross section, opposite leaves, and bilaterally symmetrical flowers. Ovary superior and four parted, developing into four nutlets. Plants produce mint oils, used medicinally and antiseptically in different parts of the world. Menthol: toothpaste, candies, gum, liqueurs, and cigarettes. Spices: rosemary, thyme, sage, oregano, marjoram, basil, lavender, catnip, peppermint, and spearmint.
Nightshade Family
Solanaceae. 3000 species concentrated in tropics of Central and South America. Flowers have fused petals with stamens fused to corolla. Superior ovary develops into berry or capsule. Foods: Tomato, white potato, eggplant, peppers, and petunia. Many are poisonous while having medicinal qualities: Belladonna drug complex - atropine: shock treatment, pain relief; scopolamine: tranquilizer - Capsicum from red pepper - gastric stimulant - Jimson week - asthma - Tobacco
Carrot Family
Apiaceae. Approximately 2000 members widely distributed in Northern Hemisphere. Savory-aromatic herbs with dissected leaves and petiole bases that form sheaths around stem. Flowers small, numerous, and arranged in umbels. Inferior ovary and two-lobed stigma. Dill, celery, carrot, parsley, caraway, coriander, fennel, anise, and parsnip. Some members poisonous; Socrates believed to have died from ingestion of water hemlock.
Pumpkin Family
Cucurbitaceae. 700 species of prostrate or climbing herbaceous vines. Flowers unisexual with fused petals. Female flowers with inferior ovary of three carpels.
Sunflower Family
Asteraceae. Second largest flowering plant family with about 20,000 species. Dandelions, lettuce, endive, chicory, artichoke, dahlia, chrysanthemum, marigold, sunflower, and thistle. Tarragon is a spice in meat and pickle. Individual flowers are florets. Florets are arranged in compact inflorescence that resembles a single flower.
Monocot Grass Family
Poaceae. Flowers wind-pollinated and highly specialized. Calyx and corolla are tiny scales. Flowers protected in boat-shaped bracts. Stigmas exposed and feathery. Leaf bases sheath stems. Contains nearly all cereals - wheat, barley, rye, oats, rice, and corn. Sugar cane - six meters tall; juice squeezed from cane then centrifuged: solids crystalized into table sugar, dark remnant becomes molasses. Baskets, fibers, thatching for huts. Citronella oil.
Monocot Lily Family
Liliaceae. Approximately 4550 members that occur in almost any area supporting vegetation. Flowers often large and their parts are in multiples of three, with sepals and petals often resembling each other.
Monocot Orchid Family
Orchidaceae. Largest family with >35,000 species, especially abundant in tropics. Widely distributed with diverse habitats. Flowers exceptionally varied in size and form. Many epiphytic on bark of trees. Others aquatic or terrestrial and saprophytic. Specific adaptations between orchid flowers and pollinators are extraordinary and sometimes bizarre. Vanilla from vanilla orchid.
