What is (a) The continued stem or midrib of a pinnately compound leaf, as in a rose leaf or a fern. (b) The principal axis in a raceme, spike, panicle, or corymb called?

rhachis — (Bot.) (a) The continued stem or midrib of a pinnately compound leaf, as in a rose leaf or a fern. (b) The principal axis in a raceme, spike, panicle, or corymb. (Webster's 1913.)

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