The division of plants and trees known as Angiospermae comes from two Latin words meaning flower and plant. Thus, angiosperms are just that: flowering plants. According to Encyclopedia Britannica, angiosperms are plants that reproduce through flowering and form seeds inside a fruit. Flowers are categorized by how they are structured. "Perfect" flowers contain both male and female reproductive organs, while "imperfect" flowers lack one or the other. All angiosperms contain some or all of four basic parts, or layers.
These are generally the most recognizable parts of a flower. Petals are the usually colorful flaps that contain the reproductive parts of the flower and recruit bees and birds to become pollinators. The flowers of many plants don't have petals, while others may possess elaborate numbers and groupings.
Think of sepals as the overall flower protectors. They are usually green, but sometimes they are colorful or disguised like a petal--as is the case with tulips. Sepals are flaplike structures at the base that enclose and protect the flower before it opens. They're also the muscles that allow certain flowers to open and close as light and weather conditions change.
A stamen is the general term for the male reproductive part of an angiosperm. Most flowers posses several of these upright structures, which consist of two main sections. The filament, or "stalk," of the stamen stands vertical inside the flower petals. Atop the filament sits the anther, which is responsible for making pollen.
The pistil is the female reproductive structure of an angiosperm. It consists of three parts: The tip of the pistil is called the stigma, which captures pollen on a sticky surface. The vertical stalk, or tube, which holds the stigma, is the style. Upon pollination, pollen travels down the style to the ovary, or egg. The ovary then produces seeds and becomes a fruit.