The inflorescence of wheat (Triticum aestivum) is botanically classified as a Spike (commonly referred to as an 'ear' or 'head').
It is a compound spike consisting of sessile spikelets borne directly in an alternating, two-ranked (distichous) arrangement on a central zigzag axis called the rachis.
Rachis is merely the central floral stem/axis.
Awns are bristle-like extensions of the lemma.
Spadix is the fleshy spike surrounded by a spathe found in maize and Araceae.