Bur

A bur (also spelled burr) is a seed or dry fruit or infructescence that has hooks or teeth.

Some other forms of diaspores, such as the stems of certain species of cactus also are covered with thorns and may function as burs.

Bur-bearing plants such as Xanthium species are often single-stemmed when growing in dense groups, but branch and spread when growing singly.

Function

Burs catch on the fur of passing animals or the clothing of people. The hooks or teeth generally cause irritation, and some species commonly cause gross injury to animals, or expensive damage to clothing or to vehicle tires.

Burs serve the plants that bear them in two main ways.

Most epizoochorous burs attach to hair on the body or legs of the host animal, but a special class of epizoochorous bur is known as the trample-bur (or trample-burr). Several species of Tribulus, Harpagophytum, and Grielum produce fruit in the form of trample-burs. As the name suggests, they attach themselves to the animal when trampled. They may hook onto the legs of animals as the large hooks of Harpagophytum do, sometimes causing serious injury, but sometimes hooking onto the leg of say, an ostrich, apparently without causing discomfort. It also might penetrate a hoof or foot pad or the tyre of a vehicle, only to be shed after being carried for a considerable time and distance; most Tribulus and Grielum species are specialised for such attachment, variously being flat, but with upward-directed spikes as in say, Grielum humifusum, or shaped like a caltrop as in some species of Tribulus that have achieved the status of cosmopolitan weeds by sticking to the tyres of aircraft.

Buré

Buré is a commune in the Orne department in northwestern France.

Population

See also

References

Bur (disambiguation)

Bur, Burs or BUR may refer to:

Places

See also