The Structure of Flowers. Angiosperms – flowering plants whose seeds are enclosed in an ovary,...
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Transcript of The Structure of Flowers. Angiosperms – flowering plants whose seeds are enclosed in an ovary,...
The Structure of Flowers
Angiosperms – flowering plants whose seeds are enclosed in an ovary, which becomes a fruit
Gymnosperms – plants whose seeds are not enclosed in a fruit; usually a conifer
Flowers are the reproductive part of the plant
They produce fruit and seeds One primary function: produce seeds
for reproduction Basic parts of a flower: sepals, petals,
stamens, pistils Pedicel (or peduncle) – flower stalk Receptacle – connects the flower parts
to the pedicel
1. What is an angiosperm?plants that bear fruit and flowers
2. The flower attaches to what part of the plant?receptacle
3. Why are flowers brightly colored?to attract insects to help them pollinate
4. Name two mammals that might pollinate a plant.bat, mouse
5. If the petals of a flower are reduced or absent, how is the plant pollinated?wind
6. The female reproductive structures are called the:pistils or carpels
7. Name the three parts of the pistil:stigma, style, ovary
8. Where are the ovules stored?ovary
9. Name the two parts of the stamen:anther and filament
10. Describe sexual reproduction in plants.the pollen from an anther is transferred to the stigma; the sperm in the pollen travels to the ovary to fertilize the egg cells
11. The ovary develops into what structure?the fruit
12. Define fruit.a structure that encloses and protects the seeds; enlarged ovary of a flower
13. Some flowers are not brightly colored at all, but have a very pungent odor that smells like rotting meat. How do you think these flowers are pollinated?flies
14. In many flowers, the pistils and stamens reach maturity at different times. Considering what you know about pollination, why would this be an advantage to the plant? decrease self-pollination
In A the filament is attached to the base of the anther
In B along the back of the anther
In C to a point at the back of the anther.
A single pistil consisting of several fused carpels (A) and several pistils each consisting of a single carpel (B)
Complete flower – has sepals, petals, stamen, and pistil
Incomplete flower – lacks one or more
Examples•Poinsettia - lacks petals (red “petals” are
actually special leaves called bracts)•Grass family – have bracts instead of
petals and sepals
Staminate flowers – lack pistils and have only stamens; male flowers
Pistillate flowers – lack stamens and have only pistils; female flowers
Monoecious plants – have staminate and pistillate flowers on the same plant•Example: Corn•The pollen is found in the tassels
(staminate flower)•The stigma is in the silk which leads to
the ovary (pistillate flower)
Dioecious plants – have staminate and pistillate flowers on different plants•Example: GinkgoStaminate flowers are found on male trees
Pistillate flowers are found on female trees
The amount of daylight, temperature, and soil fertility are some factors that can affect flowering
The chief factor for most plants is the length of daylight and night (photoperiodism)
Short-day plants – require days that consist of long periods of darkness•Ex: chrysanthemums, poinsettia, dahlia,
aster Long-day plants – require a period of
darkness shorter than a critical length•Ex: ragweed, clover, gladiolus
Day-neutral plants – amount of daylight doesn’t matter•Ex: tomato, dandelion
Some plants are also “programmed” to open/close at certain times of the day•Ex: morning glories (open early, close by
noon), four o’clocks (open around 4 p.m.), evening primrose (open after it starts to get dark)
1. What is a fruit? An enlarged ripened ovary.
2. What two functions does fruit have in regards to seeds? Protect the seeds and help to distribute them.
3. What is the difference between pollination and fertilization? Pollination is the transfer of pollen from anther to stigma. Fertilization is the union of egg and sperm cells.
4. What is a hybrid?A cross between different species of the same type of plant.
5. Why would a horticulturist desire to make a hybrid? To improve nutritional quality and improve resistance to pests and disease.
6. Between what two flower structures does pollination occur? Anther and Stigma
7. How are self-pollination and cross-pollination different?
Self-pollination is pollination between either the same flower or flowers on the same plant. Cross-pollination is pollination between flowers on two different plants.
8. How are the three types of pollen shown on pg. 53/pg 37 different from each other? Why do you think different types of pollen look different? Would this have any practical purpose?
Different depending on how plants are pollinated. Plants need to recognize their own pollen. Can only be pollinated by their own kind.
9. Explain several ways plants are specially designed to increase pollination. Smell, nectar, arrangement of stigma and stamens, decreased petals
10. What plants do only specific insects pollinate (according to the book)?Yucca flower, carrion flower, orchids
11. In flowers, where are sperm cells and egg cells found? Sperm cells – pollen, Egg cells – ovary
12.What are gametes in general? Reproductive cells
13. Explain the process of fertilization. After pollination, pollen tube grows down the style to the ovary. The sperm cells go down the pollen tube to the ovary and unite with the egg cells.
14. What role do hormones play in the formation of fruits?They cause a fruit to ripen and grow larger.
15. Explain what occurs to a fruit as it ripens. How does a ripe fruit fall from a tree? As a fruit ripens pigments cause the fruit to change color. They get softer and smell sweet. The taste also changes. The abscission layer forms at the base of the stem and “cuts” the fruit from the tree.
1. Describe how each of these fruits form. Give an example of each type.
• Simple fruit – one flower, one pistil; Ex: tomatoes, peaches, beans
• Aggregate fruit – one flower, several pistils;Ex: strawberry, raspberry
• Multiple fruit – form from several flowers whose ovaries fuse together;Ex: pineapple, fig
2. Describe the following climate-based fruit groups.
• Temperate fruit – must experience an annual cold season; grow between the polar and tropical zones; most of the US
• Tropical fruit – require consistently warm temperatures; near the equator
• Subtropical fruit – grow between the tropic and the temperate zones; southern US, Mediterranean countries
3. Which group from #2 would be found in Milwaukee?- Temperate
4. What is the primary function of fruits to a plant?to scatter the seeds
5. What is agent dispersal? Give some examples.Agent dispersal occurs when an outside agent carries the seed; the agent could be an animal (depositing the seed in fecal matter or having it attached to it), the wind, or waterEx: Wind – tumbleweeds, samaras,
dandelions Water – CoconutAnimals – burdock, teasel, fruits
6. What is mechanical dispersal? Give some examples. Mechanical dispersal is when a fruit bursts open and the seeds are scattered.
Ex: violets, witch hazel
Description – entire ovary is fleshy and juicy; does NOT include most typical berries
Examples – tomatoes, grapes, cucumbers, watermelons, oranges
Description – fleshy and juicy, but have an inner woody layer called a stone that surrounds the seed
Examples – peaches, plums, cherries, apricots, mangoes
Description – outer fleshy layer and an inner papery core
Examples – apple, pear
Description – a pod encloses several seeds; not fleshy and juicy
Examples – peas, beans, peanuts
Description – small dry seeds with one or two winglike structures
Examples – ashes, maples, elms
Description – dry fruits with a seed enclosed in a hard covering or shell
Examples – chestnuts, hickory nuts, hazelnuts, acorns
Description – consists of a seed and a thin shell
Examples – sunflower; other composite flowers
Description – each kernel is a fruit with a seed and a shell; the shell is attached directly to the seed and is called bran
Examples – members of the grass family; corn, rice, barley, oats, rye
Plants can have three different life cycles.
Annuals – one year cycle; grow, flower, die
Biennials – two year cycle; grow, become dormant, grow, flower, die
Perennials – come back each year; grow, flower, become dormant, grow, flower, become dormant, etc.
Seeds form from ovules in the ovary Contain two main parts
•Embryo (or germ in wheat) – will develop into the new plant
•Seed coat – protective covering for the seed
External parts of the seed•Hilum – scar on the seed coat where the
seed attached to the ovary•Silk scar – on corn, where the silk
attached
Parts of the embryo•Plumule – a tiny shoot that will develop
into the stem and leaves of the plant•Radicle – will develop into the root
system of the plant•Cotyledon – contains stored energy for
the plant to use before it sprouts•Endosperm – only in monocots; contains
extra energy
All plants can be divided into monocots and dicots. Each group has four main characteristics
Monocots (ex: corn)• 1 cotyledon in the seed• parallel veins• petals in multiples of 3• fibrous root system
Dicots (ex: bean)• 2 cotyledons in the seed• branching veins• petals in multiples of 4 or 5• taproot system
Seeds are generally dormant until they germinate
Favorable conditions trigger germination to take place
Some seeds can remain viable for years, others for only a few weeks
After the seed is planted, it absorbs a lot of water
The water triggers chemical changes which causes the tissues of the embryo to swell and grow
The seed coat is softened by the water so the radicle and plumule can push through
During this process, energy from the cotyledons is burned by the process of cellular respiration to provide energy for the developing plant
The root grows quickly to anchor the plant
The shoot grows rapidly The cotyledons stay attached as the
shoot pushes out of the ground It provides energy and shields
developing leaves from the hot sun Once the plant can go through
photosynthesis, the cotyledons shrivel up and fall off
1. An adequate supply of moisture2. An adequate supply of oxygen3. A favorable temperature4. Proper soil conditions5. Sufficient sunlight
Discover the horticulturist who found 300 different uses for peanuts and what three other plants he found hundreds of uses for.
This will be used for one of the extra credit questions on your test