The United States has had to find new ways to grow specialty flowers, such as lilies and zinnias.
Even though flowers are viewed for their beauty and the positive feelings they evoke, remember that a flower is a reproductive organ.
It is where sperm and egg meet.
Our trees, crops, and garden landscape are created by flowers.
The fruit of flowers sustains us.
The flowering plant life cycle has key components.
The key flower parts have functions.
The male and female gametophytes of plants.
Sexual reproduction in plants is good for the offspring because of meiosis and fertilization.
A new variation may be better for survival and reproduction in a changing environment.
When plants reproduce sexually, they alternate between two multicellular stages, one diploid and one haploid.
Figure 27.1 begins with the flowering sporophyte and moves clockwise.
The portion of the life cycle that bears flowers is dominated by the diploid sporophyte.
A flower, which is the reproductive structure of angiosperms, produces two types of spores.
A pollen grain is either wind blown or carried by an animal to the vicinity of a female gametophyte.
The male gametophyte has a pollen grain.
Sexual reproduction in plants.
There are flowers in the sporophyte.
Microspores and megaspores are produced by the flower.
A megaspore becomes a female gametophyte, which produces an egg within an embryo sac, and a microspore becomes a male gametophyte, which produces sperm.
A seed coat contains food and an embryo.
A seed becomes a new plant after dispersal.
The female gametophyte becomes "great, large").
The embryo sac within the ovule is called the female gametophyte.
The sperm that travels by way of a pollen tube to the embryo sac is nonflagellated.
The embryo is still within the ovule after a spermfertilizes an egg.
The embryo is surrounded by a seed coat as it develops into a seed.
The seeds are dispersed by the ovary becoming a fruit.
The sexual life cycle of plants is adapted to a land-based existence.
The female gametophytes are protected from desiccation.
The male gametophytes are not released until they have a thick wall.
There is no need for external water to fertilization in flowering plants.
The sperm can reach an egg with the help of the pollen tube.
The embryo and its food are kept out of the sunlight until the conditions are right for growth.
The flower is different to other angiosperms.
pollination, which helps in transporting pollen from plant to plant, is one of the benefits of flowers.
The fruits that surround the seeds are produced by flowers.
At least one carpel is needed for a complete flower.
A major factor in the success of angiosperms was the evolution of the flower.
The length of the day or time of year is one of the environmental signals that Flowering responds to.
The axillary buds develop into flowers in other plants.
In monocots, flower parts occur in multiples of three; in eudicots, they occur in multiples of four or five.
Daylilies have flower parts in threes.
The three petals and three Sepals are colored in this flower.
Eudicots are the azaleas.
The flower parts are in fours or fives.
The flower parts of a complete eudicot flower are sepals, petals, stamens, and carpels.
The flower parts are usually green.
The bud is protected by Sepals as it develops.
An open flower with a whorl of petals is the most attractive of all flowers.
The size, shape, and color of petals are attractive to specific pollinators.
Some flowers have no petals at all.
The microspores produced in the anther produce pollen grains.
The "little egg" plays a significant role in the production of megaspores and therefore female gametophytes.
A flower can have many carpels.
Sometimes several carpels are fused into a single structure, in which case the ovary is termed compound.
An orange develops from a compound ovary, and every part of it is a chamber.
Some flowers do not have petals or carpels.
Holly trees are dioecious and only females produce the berries and pollen.
haploid spores are produced by meiosis in all land plants.
Microspores become mature male gametophytes and megaspores become mature female gametophytes.
Microspores are produced in the anthers of flowers.
An anther has four sacs.
Four haploid microspores are produced by a microspore mother cell.
Two cells are enclosed by a finely sculptured wall after the haploid nucleus divides in 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884
The smaller generative cell divides to produce sperm.
The mature male gametophyte has become the pollen grain after these events.
The life cycle of plants.
There is a pollen sac in the anther.
A microspore develops into a pollen grain, which has two sperm.
An ovule in an ovary contains a megaspore mother cell.
An embryo sac contains seven cells, one of which is an egg.
A pollen tube is formed when a pollen grain contains two sperm.
A seed contains food and a developing embryo.
There are ovules in the ovary.
An ovule has a central mass of parenchyma cells almost completely covered by layers of tissue called integuments.
One parenchyma cell enlarges to become a megaspore mother cell, which undergoes meiosis, producing four haploid megaspores.
Three of the megaspores are not functional.
There are seven cells, one of which is binucleate.
When the pollen grains are ready to be released, the walls of the anther break.
Pollination is the transfer of pollen from an anther to a carpel.
Cross-pollination occurs if the pollen is from a different plant than self-pollination.
A pollen tube is formed when a pollen grain lands on the stigma of the same species.
The mature male gametophyte is contained in the germinated pollen grain.
The pollen tube goes between the cells of the stigma and the style to reach the micropyle.
One of the sperm unite with the egg to form a 2n zygote, but the other sperm unite with the two polar nuclei in the embryo sac to form a 3n endosperm nucleus.
This fertilization is unique to angiosperms.
The endosperm nucleus eventually becomes the endosperm.
The ovule is starting to develop into a seed.
The seed coat is formed from the ovule wall.
The gymnosperms, the other type of seed plant, rely on wind pollination, as do some species of flowering plants.
The plant's energy goes into making pollen to make sure it reaches a stigma.
A single corn plant can produce up to 50 million pollen grains a season.
In corn, the flowers tend to be monoecious, and clusters of tiny male flowers move in the wind.
Grass is releasing pollen.
Experts can use the shape and pattern of the pollen grain walls to identify the species that produced the particular pollen grain.
Birds, butterflies, and bats are some of the animals that carry out pollination.
The use of animal pollinators is unique to flowering plants, and it helps account for why these plants are so successful on land.
Plants have adapted to one another.
The plant uses its pollinator to ensure that cross-pollination takes place, and the pollinator uses the plant as a source of food.
The interdependency of the plant and the pollinator is the result of suitable changes in the structure and function of each.
There is observational evidence for coevolution.
For example, floral coloring and odor are suited to the sense perception of the pollinator, the mouthparts of the pollinator are suited to the structure of the flower, the type of food provided is suited to the nutrition needs of the pollinator, and the forages at the time of day that specific
There are 20,000 bees that pollinate flowers.
Bee eyes see light.
Bee-pollinated flowers are usually bright blue or yellow and not red.
The portion of the flower that contains the reproductive structures may have ultraviolet shadings called nectar guides.
The tongue of bees is fused into a tube.
The base of the flower is where the tube is usually located.
pollen is collected by bees as a food.
Bee flowers are sweet and fragrant.
The guides often point to a small floral tube that is too small for other insects to reach the bee's food.
Bee-pollinated flowers may be irregular in shape because they have a landing platform where the bee can alight.
As the bee moves toward the floral tube, it needs to brush up against the anther and stigma.
When a male wasp attempts to copulate with a flower that resembles a female, the flower spring loads pollen on the wasp's head.
When the wasp attempts to "copulate" with another flower, the pollen is perfectly positioned to come in contact with the stigma of the second flower.
The close adaptation between Page 499 pollinator and flower is emphasized by contrasting moth- and butterfly-pollinated flowers.
Both butterflies and moths have long, thin, hollow probosciss, but they have different characteristics.
Moths have a sense of smell and feed at night.
The flowers of the moths have deep tubes with open margins that allow them to reach the nectar with their long proboscis.
Butterflies are active in the daytime but have a weak sense of smell.
Butterflies can see the red color of the flowers, but they are odorless.
Butterflies need a place to land.
Butterflies prefer the flowers composed of a compact head of many individual flowers.
The long, slender floral tube is accessible to the long, thin butterfly proboscis.
The hummingbirds are the most well-known bird pollinators in North America.
These small animals do not have a good sense of smell.
When they feed, they hover.
The flowers that are pollinated by hummingbirds are red with a slender floral tube and margins that are curved back and out of the way.
The flowers have little odor.
Bats are able to gather food in a variety of ways.
Bats have a sense of smell.
Those that are pollinators have a long tongue and keen vision.
Bat-pollinated flowers are usually light-colored or white at night.
They have a strong smell similar to that of bats.
The flowers are sturdy and can hold up when a bat inserts part of its head.
When insects were not as diverse as they are today, wind alone carried pollen, which was 250 million years ago.
It's a hit-or-miss affair when it comes to wind-pollination.
The first insects to carry pollen directly from plant to plant were beetles.
Natural selection favored flowers with features that would attract pollinators because they were likely to produce more fruit.
More and more flower variations developed as cross-fertilization continued.
There are over 6 million species of insects and 270,000 species of flowering plants.
The success of angiosperms is thought to have contributed to the success of insects.
A bee-pollinated flower is a different color than red.
The bee's body is covered with the reproductive structures of the flower.
A butterfly-pollinated flower contains many individual flowers.
The broad expanse gives room for the butterfly to land, after which it lowers its proboscis into each flower.
The curved back of hummingbird-pollinated flowers allow the bird to reach the rich supply of nectar.
The reproductive structures are touched by the bird's forehead and other body parts.
Large, sturdy flowers that can take rough treatment are bat-pollinated.
The head of the bat is positioned so that it can lap up the liquid.
By the time flowering plants appeared in the fossil record, insects were present.
Plants and their animals have been evolving for millions of years.
Plants with flowers that attracted a pollinator produced more seeds.
The pollinators that were able to find and remove food from the flower were more successful.
The reproductive parts of the flower are positioned so that the pollinator can pick up the pollen from one flower and deliver it to another.
The mouth parts of the pollinator are good for gathering the nectar from these plants.
One example of coevolution that has occurred is between bees and the plants they pollinate.
Yellow, blue, or white are the colors bees can see in beepollinated flowers.
The bees respond to UV markings that help them locate their food.
Humans can't see light in the UV range, but bees can.
A bee has a basket on its hind legs that it uses to carry its pollen back to the hive.
Many fruits and vegetables are dependent on bee pollination, leading to great concern that the number of bees is declining due to disease and the use of pesticides.