Foxtail (diaspore)

A foxtail is a spikelet or cluster of a grass, that serves to disperse its seeds as a unit. Thus, the foxtail is a type of diaspore or plant dispersal unit. Some grasses that produce a foxtail are themselves called "foxtail", also "". They can become a health hazard for dogs and other domestic animals, and a nuisance for people. Foxtail Grass is most commonly found in the Great Plains where bison and other native animals graze on it. Fires started by lightning can burn down Foxtail Grass, but the grass has roots underground that allow it to grow back.

The name "foxtail" is applied to a number of grasses that have bushy spikes of spikelets that resemble the tail of a fox. Not all of these are hazardous; most of the hazardous ones are in the genus Hordeum, and are also called "wild barley".

Grasses known as foxtails include:

Other grasses also produce hazardous spikelets. The spikelets are sometimes called foxtails, even though the grasses are not.

All foxtails have a hardened tip, sometimes called a "callus", and retrorse barbs, pointing away from the tip of the callus. Wild barleys have clusters of three spikelets, and the callus is the portion of the rachis to which they attach. In other grasses, such as needlegrass and brome grasses, the foxtail consists of a single spikelet, with the callus being the hardened lemma tip. Retrorse barbs can be found on the callus, the lemmas, and the awns.

The spikelets or spikelet clusters of foxtails are adapted for animal dispersal: The foxtails disarticulate easily, the barbs cause the foxtail to cling to fur, and movement of the animal causes the foxtail to burrow into the fur, since the barbs permit it to move only in the direction of the callus. In wild mammals that inhabit the native ranges of foxtail grasses, the fur is ordinarily short enough that the foxtails will eventually become dislodged, dispersing the seed.

Foxtails can become a health hazard for dogs and other domestic animals, and a nuisance for people. In dogs and other domestic animals the foxtails can become irreversibly lodged. Foxtails can also enter the nostrils and ear canals of many mammals. In all these cases, the foxtail can physically enter the body through muscular movements or, in the case of nostrils, air flow, can cause the foxtails to continue to burrow through soft tissues and organs, causing infection and physical disruption, which in some cases can result in death. In humans, foxtails can work through clothing, particularly fabric shoes and socks, causing discomfort to people while walking.

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