Rachis

Rachis is a term used in various fields of biology to refer to a main axis or "backbone" of some kind. In botany, it refers to the main stem of an inflorescence or a compound leaf. In zoology, it refers to the long central shaft of a feather. In human anatomy, it is another name for the spinal column.

Botany

In botany, the rachis is the main axis of a compound leaf or an inflorescence. In the case of a compound leaf, the rachis replaces the petiole. The leaflets of the compound leaf are attached to the rachis. In an inflorescence, the rachis is the stem bearing the floral parts. The length of the rachis can be one of the factors influencing the shape of the inflorescence.

Zoology

In zoology, the rachis is the long central shaft of a feather. It bears the barbs of the feather, which in turn bear the barbules. The rachis is strong and lightweight, and its shape and rigidity contribute to the feather's overall function in flight or insulation.

Human anatomy

In human anatomy, rachis is another name for the spinal column. The term is not commonly used in this context, but can be found in older or more technical sources.

See also

• Inflorescence
• Feather
• Spinal column

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