In a hypogynous flower, the arrangement of various reproductive organs takes a certain form. The flower’s perianth, which refers collectively to its petals and any sepals, together with its stamen, the male reproductive organ, all attach below the pistil, the female reproductive organ. In the word hypgynous, you can see the Greek root "hypo-," meaning below or under, and "gynous," meaning female.
The Buttercup (Ranunculus) has hypogynous flowers, which usually blossom between spring and summer. For best results, plant them in full sun, where you can expect growth reaching up to 2 feet tall. The flowers range widely in color, especially among the "Persian buttercup" variety, though yellow buttercups are most commonly associated with the species. Generally buttercups grow best in climates where temperatures don’t dip below 25 degrees Fahrenheit; cooler temperatures can damage flowers. According to the USDA hardiness zone map, the flowers do best in zones 4 through 9, spanning much of the continental United States.
Magnolia are another kind of hypogynous flower. Aside from their similar flower structure, magnolias differ dramatically from buttercups. Whereas buttercups grow low to the ground on herbaceous stems, magnolia grow as shrubs or trees with simple leaves that grow in an alternate pattern. Magnolia flowers grow individually, with a somewhat elongated form. On average, they measure around 3 inches across. They can vary in color from white to pink to purple, sometimes even tinged with green or yellow. Many of the flower’s parts, such as the petals, have a spiral-like form. The magnolia has many stamens with short filaments and branched anthers.
The flowers of plants belonging to the Piperaceae family generally have hypogynous flowers, including the black pepper plant (Piper nigrum), best known for the culinary use of its dried fruits for seasoning. Black pepper grows best off the coast of India, its native habitat, and throughout southeast Asia, where its popular culinary use has instigated more widespread commercial cultivation. In the western hemisphere, most black pepper cultivation takes place in Brazil’s warm and humid Amazon regions. Black pepper grows as a vine. In nature, it relies on trees for support; in agricultural environments, farmers often use hardwood trellises to support the plant. If you wish to plant black pepper, propagate it by taking cuttings of a robust, mature plant. It should take around three years for the new plant to begin bearing fruit. If you instead plant a black pepper vine from a seedling, it will take between four and five years until your first harvest.