What is a Flower?

Study Notes

What is a Flower?

Flowers are modified leaves attached to the stem of a plant, containing complex reproductive organs and specialized cells.
They serve a reproductive role to ensure pollination and seed formation are successful.
The showy petals surround the complex reproductive structures within the feathery male pollen-producing stamen, which encircles the dark female pistil at the flower center.

The Study of Flowers

The scientific study of plants is called botany.
Botanists study the structures and functions of plants, their evolutionary relationships, growth, change, reproduction, and more.
The study of the anatomy of a flower is a specialty within the field of botany.

Basic Structure of a Flower

The basic flower structure includes four circular layers of specialized tissues called whorls.
The structure of flower whorls, from outer to innermost, is: calyx (sepals), corolla (petals), androecium (male reproductive structures), and gynoecium (female reproductive structures).

Complete vs. Incomplete Flowers

Complete flowers have all four whorls present: sepals, petals, and both male and female reproductive structures.
Incomplete flowers are missing one of the four whorls.
Examples of plants with incomplete flowers include corn and most grasses, which lack petals (corolla whorl) and sometimes sepals (calyx whorl).
Other examples of incomplete flowers are found on some squash and cucumber plants, which have sepals and petals but lack either male or female reproductive whorls.

Whorls

Whorls are specialized layers that make up the structure of a flower.
Each whorl has a specific reproductive function.
The whorls, moving from outer to innermost, are: calyx, corolla, androecium, and gynoecium.
Calyx (sepals) protects the flower bud as it forms.
Corolla (petals) attracts pollinators.
Androecium (male part) consists of one or more stamens that produce pollen.
Gynoecium (female part) consists of one or more carpels that produce ovules.

Male and Female Parts of a Flower

The male whorl is called the androecium, which consists of the flower parts that produce pollen.
The female whorl is called the gynoecium, which is responsible for creating the ovule.
Pollination occurs when pollen is transferred onto the stigma and moves toward the ovule.

Female Structure of a Flower

The female structures of a flower are collectively called the gynoecium.
The gynoecium contains the carpel, which consists of the stigma, style, and ovary.
The stigma is sticky to trap pollen grains.
The style is a thin tube that connects the stigma with the ovary.
The ovary contains ovules, or female sex cells.

Male Structure of a Flower

The male structure of a flower is called the androecium.
One or more stamens make up the androecium.
Each stamen consists of an anther that produces pollen and a filament that supports the anther.

Description

Learn about the scientific structure and function of flowers, including their modified leaves, reproductive organs, and specialized cells. Understand the role of flowers in plant reproduction and their connection to angiosperms.