Bracts are modified leaves associated with a plant’s reproductive parts. They typically appear at the base of flowers, flower clusters, or along an inflorescence axis. Their appearance varies significantly across plant species.
Distinguishing Features
Bracts often differ in size, color, shape, or texture from a plant’s typical foliage. They are generally positioned just below a flower or flower cluster, distinguishing them from regular leaves. Unlike petals or sepals, which are direct flower components, bracts are accessory structures found near the flower. Their striking appearance and positioning can lead to them being mistaken for true petals.
Bracts can range from small, green, miniature leaves to large, brightly colored, and petal-like structures. They might be papery, scale-like, or spiny, depending on the plant species. This adaptive diversity allows them to serve specific purposes in different plant environments.
Primary Functions
Bracts perform several roles contributing to a plant’s reproductive success. One primary function is protection, where bracts enclose and shield developing flower buds or seeds from environmental stressors. They offer shelter to delicate reproductive organs, especially in young buds where bracts are often folded around them.
Another important function of bracts is attracting pollinators. Many plants have evolved brightly colored or unusually shaped bracts that draw insects or other animals to the often less conspicuous true flowers. These showy bracts effectively act as visual signals, guiding pollinators towards the small, actual flowers. This visual enhancement increases the likelihood of successful pollination. Bracts can also provide structural support for the flower or inflorescence. In some cases, they can even aid in seed dispersal or detect acoustic signals from bats.
Notable Plant Examples
Bracts are prominently displayed in several familiar plants. The Poinsettia (Euphorbia pulcherrima) is a well-known example where the vibrant red, pink, or white structures, often perceived as petals, are modified leaves called bracts. The true flowers are small, yellow structures located in the center of these colorful bracts. These showy bracts attract pollinators to the tiny central flowers.
Bougainvillea is another plant widely recognized for its vivid displays, which come from its brightly colored bracts rather than its inconspicuous true flowers. These papery bracts can be purple, magenta, pink, orange, or white and surround the small, white, trumpet-shaped flowers. The colorful bracts are the plant’s main attraction, drawing pollinators and contributing to its ornamental appeal. Similarly, in Dogwood trees (Cornus florida), the large, petal-like structures that emerge in spring are actually four showy bracts that surround a cluster of small, greenish-yellow true flowers. These white or pink bracts are responsible for the tree’s distinctive and admired appearance.