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seed to flower

The seed-flower life cycle

Humans have many reasons to grow plants. We use them for food, for building materials, for pleasure and for many other purposes. A plant really just has one reason to grow – to reproduce and make more plants like it! A life cycle shows how living things grow, change and reproduce themselves. Many plant life cycles include seeds. This article describes the life cycle of flowering plants.

Flowering plants grow from seeds

Flowering plants produce seeds that are then dispersed from their parent. When a seed comes to rest in an appropriate place with conditions suitable to its germination, it breaks open. The embryo inside the seed starts to grow into a seedling. Roots grow down to anchor the plant in the ground. Roots also take up water and nutrients and store food. A shoot grows skywards and develops into a stem that carries water and nutrients from the roots to the rest of the plant. The stem also supports leaves so they can collect sunlight. Leaves capture sunlight to make energy for the plant through the process of photosynthesis.

Adult plants produce flowers

When the seedling matures into an adult plant and is ready to reproduce, it develops flowers. Flowers are special structures involved in sexual reproduction, which involves both pollination and fertilisation,

Pollination

Pollination is the process by which pollen is carried (by wind or animals such as insects or birds) from the male part of a flower (the anther) to the female part (the stigma) of another or the same flower. The pollen then moves from the stigma to the female ovules.

Fertilisation

Pollen has male gametes containing half the normal chromosomes for that plant. After pollination, these gametes move to the ovule, where they combine with female gametes, which also contain half the quota of chromosomes. This process is called fertilisation. After fertilisation, the combined cell grows into an embryo inside a seed. The embryo is a tiny plant that has root, stem and leaf parts ready to grow into a new plant when conditions are right.

Length of life cycle

Flowering plants all go through the same stages of a life cycle, but the length of time they take varies widely between species. Some plants go though their complete cycle in a few weeks – others take many years.

Annuals are plants that grow from a seed. They flower, make new seeds and then die – all in less than a year. Some go through this cycle more than once in a year. Corn, beans, zinnia and marigolds are examples of annuals.

Biennials are plants that take 2 years to go through their life cycle. They grow from a seed and then rest over winter. In spring, they produce flowers, set seeds and die. New plants grow from the seeds. For example, parsley is a biennial.

Perennials are plants that live for 3 or more years. Some, such as trees, flower and set seeds every year for many years. Other types of perennials have stems and leaves that die away over winter, but the plant continues to live underground. In the spring, new stems grow, which later bear flowers. Tulips and daffodils are examples of this type of perennial.

Nature of science

Scientists often use curious terms. Sometimes the terms relate to their Greek or Latin origins. The English word ‘gamete’ refers to a reproductive cell that unites with another to form a new organism. In Greek, it is similar to the words ‘wife’, ‘husband’ and ‘to marry’.

Humans have many reasons to grow plants. We use them for food, for building materials, for pleasure and for many other purposes. A plant really just has one reason to grow – to reproduce and make more plants like it! A life cycle shows how living things grow, change and reproduce themselves. Many plant life cycles include seeds. This article describes the life cycle of flowering plants.

How Does a Seed Become a Flower?

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Flowering plants, which represent a large portion of the plant kingdom, follow a regular and predictable pattern of growth from seed to flowery maturity unless something abnormal happens to their environment such as an untimely freeze, a drought or extreme heat wave. A flowering plant may sprout, flower, produce seeds and die in a single year or may grow, flower and produce seeds for a number of years before dying.

Germination

The first stage of a flowering plant’s life is germination, where an embryonic plant emerges from the seed. Seeds germinate in response to the correct amount of daylight, soil temperature, rainfall and other cues such as a spell of cold weather before warm weather. The correct conditions trigger growth in the plant embryo contained in the seed. The embryo uses nutrients stored in the seed for its initial growth. The embryo breaks through the seed coat, and sends roots downward into the dirt and a green shoot upward to the soil surface.

Plant Growth

After germination, a flowering plant’s roots collect water and soil nutrients while its green leaves convert the energy of sunlight into sugars. The water, nutrients and sugars fuel a rapid vegetative growth stage where the plant goes from being a tiny sprout to a mature member of its species. The length of the growth stage varies with the species. Annuals, which live for only one year, have a single vegetative growth stage. But flowering plants that live for multiple years have a growth stage that adds stems, leaves and roots each year they live.

Flowering Stage

When a flowering plant reaches the right stage of maturity, it forms buds on its stems that will expand into flowers. The timing of the flowering stage varies with the species and the environmental conditions. Flowers are the sexual reproductive organs of the plant. Some flowering plants have male and female parts in the same flower. Others have separate male and female flowers on the same plant, while still others have separate male and female plants. The female flower part, called the pistil, contains the ovary that will nurture the seeds of the next generation. The male flower parts, called stamens, contain the organs that produce the pollen that will fertilize the ovary.

Reproduction

Pollen is carried from the stamens to the pistil by wind or by a pollinator such as a honeybee or moth. When a pollen grain lands on the tip of the pistil, it releases sperm that travel down inside the pistil to fertilize the ovary at the base of the pistil. Once pollination and fertilization have occurred, seeds start to grow in the ovary. Meanwhile, the flower withers away as the ovary swells and the seeds within it ripen until they are ready to release. With annuals, the plant dies after the ripe seeds are released. With perennials, once the ripe seeds are released the plant stores food in its roots for use next year, and then goes into dormancy until environmental conditions trigger a new round of growth, flowering and seeding.

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Herb Kirchhoff has more than three decades of hands-on experience as an avid garden hobbyist and home handyman. Since retiring from the news business in 2008, Kirchhoff takes care of a 12-acre rural Michigan lakefront property and applies his experience to his vegetable and flower gardens and home repair and renovation projects.

How Does a Seed Become a Flower?. Flowering plants, which represent a large portion of the plant kingdom, follow a regular and predictable pattern of growth from seed to flowery maturity unless something abnormal happens to their environment such as an untimely freeze, a drought or extreme heat wave. A flowering plant …