- This article is about a term used in biology; for the genus of land snails, see Rhachis.
|This article does not cite any references or sources. (December 2009)|
In zoology 
In vertebrates a rachis can refer to the series of articulated vertebrae, which encase the spinal cord. In this case the rachis usually form the supporting axis of the body and is then called the spine or vertebral column. Rachis can also mean the central shaft of pennaceous feathers.
In botany 
A ripe head of wild-type wheat is easily shattered into dispersal units when touched or blown by the wind. A series of abscission layers forms that divides the rachis into dispersal units consisting of a small group of flowers (a single spikelet) attached to a short segment of the rachis. This is significant in the history of agriculture, and referred to by archaeologists as a "brittle rachis", one type of shattering in crop plants.