Wheat is a type of cereal grass. When the wheat grain is harvested the stalks that remain are referred to as straw. Hay however, is dried grass.
Awns.
Barley looks very much like wheat. If you've seen a wheat plant before, then barley has often much longer awns (those long things that stick out from the seeds on the seed head) and is often a more yellowish colour. Wheat tends to be more reddish in colour, with shorter awns. The seeds are not clumped together as wheat is, as the seeds are a bit more smoother on the head than wheat. In most barley seed heads, there are less seeds on a barley seed head than on a wheat seed head. See the links below for pictures of barley plants and seed heads and pictures of wheat plants for comparison.
Wheat has a more broader and "coarser" seed head than barley, and the tufts/bristles (called awns) are shorter in wheat than barley. Corn or Maize is a much larger cereal grass, with the seeds on a cob enclosed by a sheath. The awns are very floppy and finer than either wheat or corn. Corn can grow up to 10 feet in height whereas barley and wheat only grow up to 4 feet in height. As far as deciphering individual grains, wheat is darker in colouration than barley. Corn is much different shaped than wheat or barley, having a rounded head as opposed to the sharp oval/diamond shape that wheat and barley have.
The "beard" portion of the seed head of a cereal grain plant is called, collectively, awns. A single awn is the bristle portion of a seed of grain that extends up at the top point of this seed. The hull protects the endosperm, germ and bran portion of the grain seed. Cereal grains which have such "beards" or awns are wheat, barley, rye and triticale. Rice, corn, and oats do not have such awns due to the different characteristics of their inflorescences or flowering portion of the grass plant.
the awns-er is learn math
An awner is a device for cutting the awns from grain.
awns
awns spines, thorns
setae
AWNS
Awn: A slender, bristlelike appendage found on the spikelets of many grasses.