The spine.
The continued stem or midrib of a pinnately compound leaf, as in a rose leaf or a fern.
The principal axis in a raceme, spike, panicle, or corymb.
The shaft of a feather. The rhachis of the after-shaft, or plumule, is called the hyporhachis.
The central cord in the stem of a crinoid.
The median part of the radula of a mollusk.
A central cord of the ovary of nematodes.
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