The most important species, T. aestivum L., includes five subspecies. This subspecies has a long, slender spike which is somewhat flattened. Spikelets are 2 to 5 flowered, relatively far apart on the stem and nearly erect. Awns are either lacking or less than half an inch long. Stem centers are generally hollow but may be pithy.
Leaves are more narrow than in some other wheats.
Kernels may be red or white, hard or soft. This is the source of most of the wheat varieties cultivated in the United States. Over 200 such varieties have been described, with near 100 now cultivated. They may be either spring or winter type and comprise nearly 95 percent of the wheat grown in this country. Principal use is for flour.