rachilla

noun

(diminutive of Gr. rakhis: spine) A diminutive or secondary axis; a branch of a rachis; the minute axis bearing the individual florets in grass and sedge spikelets; the zigzag center upon which the florets are arranged in the spikelet of grasses or in some sedges; the axis of a grass spikelet, above the glumes. the secondary axes of decompound fern fronds. Also rhachilla.