Capitulum

Capitulum is a term used in various fields of biology and anatomy to describe a rounded, knob-like structure. The term is derived from the Latin word for "little head." Capitula can be found in plants, arthropods, and vertebrates, each with distinct characteristics and functions.

In Botany

In botany, a capitulum (plural: capitula) refers to a type of inflorescence where the flowers are arranged in a dense cluster. This structure is characteristic of the Asteraceae family, which includes plants such as daisies, sunflowers, and dandelions. The individual flowers, or florets, are attached directly to a flattened, expanded part of the stem called the receptacle. The outer florets are often ray florets, which are typically sterile and serve to attract pollinators, while the inner florets are disk florets, which are usually fertile.

In Arthropods

In arthropods, particularly in ticks and mites, the capitulum refers to the mouthparts. The capitulum includes structures such as the chelicerae, hypostome, and palps, which are used for feeding and attachment to the host. The capitulum is an important feature for the identification and classification of different species within these groups.

In Vertebrate Anatomy

In vertebrate anatomy, the term capitulum is used to describe a rounded, knob-like structure on a bone. One of the most well-known examples is the capitulum of the humerus, which is a smooth, rounded eminence on the distal end of the humerus bone in the human arm. It articulates with the radius bone of the forearm, allowing for the flexion and extension of the elbow joint.

Related Pages

• Inflorescence
• Asteraceae
• Ticks
• Mites
• Humerus
• Radius