Although all grass seeds may seem to appear the same, they have differences. Most grass seeds are easily distinctive in appearance from one another. Some of the main differences in various grass seeds include size, shape and color. While many seeds can be seen easily with the naked eye, some details of a seed, such as the fine hairs of a red fescue seed, need a magnifying device for viewing, notes Mississippi State University.
Grass seeds fall into the two broad categories of cool weather and warm weather seeds. Cool weather grass seeds, which generally grow in Northern regions, actively grow during spring and fall when soil and temperatures are cool.
Warm season grass seeds grow during June through mid-September in climates with warmer soil and air temperatures. Common cool season grasses include orchard grass, Kentucky bluegrass, tall fescue, Virginia wild, and smooth bromegrass, notes the University of Connecticut. Warm season grasses are those such as switch grass, big bluestem, broom sedge, and Indian grass.
Seeds range in size from ¾ inch or larger to the smallest seeds, which are less than ¼ inch, according to the University of Wisconsin. The largest seeds are smooth bromegrass. Medium size seeds include tall fescue, perennial ryegrass, quackgrass, annual ryegrass and orchardgrass. The smallest seeds are the yellow foxtail, green foxtail, giant foxtail, creeping foxtail, Kentucky bluegrass, red canarygass, Timothy and barnyard grass.
Tall fescue seed is shaped as a golf tee, with its sides being somewhat curved, notes the University of Kentucky. Ryegrass seed, which is wide, flat and square-shaped, has more of a straight outline. Kentucky bluegrass seed has a darker, straw color. Timothy seed, which is pale brown, is round and may have have the palea and lemma attached, which are overlapping scales, occurring in pairs. Rye seed has an elongated shape and is green or gray, with its seed coat generally appearing scaly.
Barley grass seed has the palea and lemma remaining unattached and may have awn remnants attached.
Some seeds such as Kentucky bluegrass, Indian grass, big bluestem and little bluestem have awns, also known as "beards." These seeds should be de-bearded, which is a process in which a machine removes the awns. De-bearding helps seeds pass easier through seeding devices, according to Illinois Department of Natural Resources.
It can be hard to determine the identity of a seed found in some seed mixtures, notes Mississippi State University. The difficulty varies, depending on the type of seed mixtures. For example, it's possible to make a correct determination of a mixture containing creeping bent and redtop grass seeds. On the other hand, it's impossible to make an accurate seed identification in a mixture of Astoria bent and colonial bent seeds.