Structures of Bougainvillea Flowers

Perfect Flowers

• Flowers are specialized parts of plant stems where sexual reproduction takes place. They are the bougainvillea's most distinctive feature. All flowers contain both reproductive and accessory parts, such as the floral bracts, which are part of the flower, though not directly involved in pollination. Bougainvilleas have "perfect" flowers, which are defined as flowers that contain both stamens and pistils, but not necessarily sepals or petals. The stamen contains male reproductive organs, while the pistil encompasses female reproductive organs. Bougainvillea have one simple pistil that is surrounded by stamen. In most cultivars, the stigma protrudes from the tube while the anthers cluster around the base of the style, the stalk connecting the ovary to the stigma.

Bracts

• Bracts may be either leaf-like, like on poinsettias, or petal-like. Bougainvilleas have floral bracts outside the flower calyx, which emulate flower petals. They serve to attract attention to the plants inconspicuous flowers. Bracts, which are approximately 2- inches in length, attach to flowers on short stems at mid-rib. Bracts may be white, yellow, pink, magenta, mauve, purple, red or orange. They will change color over their life span. Bracts are most vibrant when flowers are in bloom; however, they will maintain their color up to several months following flowering. Over time, they slowly fade in color, eventually taking on the color and texture of paper.

Flower Parts and Pollination

• The perianth of the bougainvillea, which encompasses the calyx and corolla is a tubular form that terminates into five lobes. A pollinator-attracting fragrance is emitted on the margins of the perianth. Nectar, which also attracts pollinators, is produced in the nectary at the base of the flower stamens. Nectar is continuously secreted during the life of the flower. Colorful bracts, which serve to attract pollinators, also play an important role in pollination of this self-incompatible plant. Butterflies and hummingbirds are best-adapted to access the nectar from the thin flower throat.

Blooming

• Bougainvilleas flower best when exposed to intense light, moderate temperatures and long nights. These conditions are most prevalent in the spring throughout the growing range of the bougainvillea. Dry spells and cool spells are thought to trigger plant blooms. During bloom, flowers appear all along the branches of the plant in the axils of leaves.