Flowering plant

Flowering Plant

Diagram of a flowering plant showing the structure of a daffodil flower.

Flowering plants, also known as angiosperms, are the most diverse group of land plants. They are characterized by the presence of flowers and fruit, which distinguish them from other plant groups such as gymnosperms. Angiosperms are the dominant form of plant life in most terrestrial ecosystems, contributing significantly to the biodiversity and ecological balance of the planet.

Characteristics

Flowering plants are defined by several key characteristics:

• Flowers: The reproductive structures of angiosperms, flowers facilitate pollination and the development of seeds. Flowers can vary greatly in size, shape, color, and arrangement.

• Fruits: After fertilization, the ovary of the flower develops into a fruit, which encloses the seeds. Fruits aid in the dispersal of seeds by various mechanisms, including wind, water, and animals.

• Double Fertilization: A unique feature of angiosperms is double fertilization, where one sperm fertilizes the egg to form a zygote, and another sperm fuses with two other nuclei to form the triploid endosperm, which nourishes the developing embryo.

• Vascular Tissues: Angiosperms possess well-developed vascular tissues, including xylem and phloem, which transport water, nutrients, and food throughout the plant.

Xylem vessels in a herbaceous dicot stem.

Reproduction

The reproductive cycle of flowering plants involves the production of male and female gametes, pollination, fertilization, and seed development.

• Gametophyte Development: The male gametophyte (pollen) and female gametophyte (embryo sac) develop within the flower. The pollen is produced in the anther, while the embryo sac forms within the ovule.

Embryo sac with female gametophyte in an angiosperm.

• Pollination: Transfer of pollen from the anther to the stigma of a flower. This can occur via wind, water, or animal vectors.

• Fertilization: Following pollination, pollen tubes grow towards the ovules, allowing sperm cells to fertilize the egg cell and form a zygote.

• Seed Development: The fertilized ovule develops into a seed, which contains the embryo and stored food.

Diversity

Angiosperms are incredibly diverse, with over 300,000 species. They are divided into two main groups:

• Monocots: Characterized by a single cotyledon, parallel leaf venation, and floral parts typically in multiples of three. Examples include grasses, lilies, and orchids.

• Dicots: Characterized by two cotyledons, net-like leaf venation, and floral parts typically in multiples of four or five. Examples include roses, sunflowers, and oaks.

Peas in a peapod, an example of a dicot.

Ecological Importance

Flowering plants play a crucial role in ecosystems as primary producers, providing food and habitat for a wide range of organisms. They are also vital for human agriculture, providing fruits, vegetables, grains, and other resources.

Mountain ash trees, an example of flowering plants in an urban environment.

Adaptations

Angiosperms have evolved a variety of adaptations to survive in diverse environments:

• Water Conservation: Some species, like cacti, have adapted to arid environments by developing thick, water-storing tissues.

• Pollination Strategies: Flowers have evolved various forms, colors, and scents to attract specific pollinators, such as bees, birds, and bats.

• Parasitism: Some flowering plants, like the Orobanche species, are parasitic and obtain nutrients from other plants.

Orobanche purpurea, a parasitic flowering plant.

Related Pages

• Gymnosperm
• Pollination
• Seed dispersal
• Photosynthesis