Involucre – Definition & Detailed Explanation – Botanical Terms Glossary

What is an involucre?

An involucre is a structure found in certain plants that surrounds or encloses a flower or a cluster of flowers. It is typically made up of bracts, which are modified leaves that are often smaller and more colorful than the plant’s regular foliage. The involucre can vary in size, shape, and color depending on the plant species.

What are the functions of an involucre?

The main function of an involucre is to protect the flower or inflorescence (cluster of flowers) within it. It can provide physical support, help attract pollinators, and serve as a protective barrier against environmental factors such as wind, rain, and herbivores. In some cases, the involucre can also play a role in seed dispersal by aiding in the formation of fruit or seed capsules.

What are the different types of involucres?

There are several types of involucres found in plants, including simple involucres, compound involucres, and bracteate involucres. Simple involucres consist of a single layer of bracts surrounding the flower or inflorescence, while compound involucres have multiple layers of bracts. Bracteate involucres are those in which the bracts are fused together at the base, forming a cup-like structure around the flower.

How do involucres vary in appearance?

Involucres can vary greatly in appearance depending on the plant species. They may be shaped like a cup, a cone, a tube, or a ring, and can be smooth, hairy, spiny, or brightly colored. Some involucres are inconspicuous and blend in with the plant’s foliage, while others are showy and serve as a prominent feature of the plant.

How are involucres used in plant identification?

Involucres are often used as a key characteristic in plant identification. The size, shape, color, and texture of the involucre can help botanists and horticulturists differentiate between different plant species. By examining the involucre, one can determine the family, genus, or even species of a plant, especially when other identifying features are not readily available.

What are some examples of plants with prominent involucres?

There are many plant species that have prominent involucres, some of which are well-known for their unique and striking appearance. One example is the sunflower (Helianthus annuus), which has a large, showy involucre made up of bright yellow bracts that surround the central disc florets. Another example is the poinsettia (Euphorbia pulcherrima), whose red bracts are often mistaken for flowers but are actually part of the involucre. Other plants with notable involucres include the bracts of the dogwood tree (Cornus florida) and the colorful bracts of the bougainvillea (Bougainvillea spp.).