» Rachis's also the alternate spelling of Ratchis, king of the Lombards, 744-749. The rachis 's the main axis of the inflorescence, or spike, of wheat and other cereals, to which the spikelets are attached. It's also the part of the axis that the pinnae are attached to in ferns, the main stem of a compound leaf (such as in Acacia), or the main axis in compound inflorescences in other angiosperms. Spikelets are small inflorescences bearing one or more florets, or small flowers, along with a set… (More on Rachis)