Rachis

In biology, a rachis /ˈreɪkɪs/ (from the Ancient Greek: ῥάχις [rhákhis], "backbone, spine")[1] is a main axis or "shaft".

In this case the rachis usually forms the supporting axis of the body and is then called the spine or vertebral column.

The central spine that remains when an Abies seed cone disintegrates is also called the rachis.

A ripe head of wild-type wheat is easily shattered into dispersal units when touched or blown by the wind.

This is significant in the history of agriculture, and referred to by archaeologists as a "brittle rachis", one type of shattering in crop plants.