Though the parts of flowering plants might arrange themselves in different ways or boast varying colors or take on a number of shapes, the differences are only variations on a single structural theme. All flowering plants--or angiosperms--possess roots, stems and leaves. They also possess flowers that become fruits when pollinated, setting angiosperms apart from other types of plants. All parts on an angiosperm are necessary, even parts like flowers that may seem merely ornamental. Additionally, on every angiosperm, the basic parts function the same way and for the same purpose.
A flower is the part of a flowering plant that is unique to angiosperms alone. Flowers are also necessary to produce still more angiosperms, since flowers are sexual organs, existing for the sole purpose of reproduction. As such, flowers may have male and/or female parts. The male structures of a flower are stamens, which produce pollen. That pollen contains sperm which is delivered via wind, bees or other pollinating creatures to the female pistils of a flower. At the base of a pistil is an ovary, which contains eggs.
It may seem that only the stamen and pistil of flowers are actually necessary. While they are the only parts needed to create seeds, the petals and sepals of a flower serve a function, too. Sepals protect the other parts of a flower while it is in bud form. Petals protect, too, and also attract pollinators with color, scent and nectar.
A fruit is the product of the successful union of egg and sperm. The fusion creates the seed. Meanwhile, parts of the flower transform into fruit. For instance, looking at the core of an apple, you are looking at what once was the ovary. The floral tube--that is, the place where parts of the flower are joined--is the fleshy part of an apple.
Though people think of fruit as being limited to sweet foods like strawberries, foods like beans and squash are included, too. Any crop that develops from a flower is considered a fruit. Zucchini, tomatoes, and peas are all fruit.
Stems are the highway systems of angiosperms, transporting water, food and minerals from the parts that created or absorbed them to the parts that need them. Stems can either be woody, in which case we call them trunks and branches, or herbaceous.
Stems produce buds, which become either new stems, flowers or leaves. When the buds occur at the ends of stems, they're called terminal buds. Lateral buds grow from the side of stems.
Leaves are there to create food. They do this by collecting sunlight on their broad sides or, blades, and converting it. This process of changing energy to food is called photosynthesis.
Some plants need more than sunlight and also use their leaves to catch insects, which they digest. The leaves of the Venus flytrap are hinged and slam shut once trigger hairs are disturbed. Sundews have a sticky substance that won't let insects escape. Meanwhile, the pitcher plant has leaves that are arranged to collect water. Insects drown in the water and the plant digests them at leisure.
Plants need water and minerals, and roots go out and get them. Roots spread beneath the ground, sometimes with a central taproot that drills deep through soil, sometimes with a shallow system that relies on breadth over depth.
Some roots store food for the plant, which we humans conveniently can eat, too. Carrots, for instance, are edible taproots. The sweet potato is another root food storage organ for us to enjoy.