How are Burrs dispersed?
Answers
Burr seeds - Animal dispersal:
- Animals disperse seeds in several ways.
- First, some plants, like the burr at left, have barbs or other structures that get tangled in animal fur or feathers, and are then carried to new sites.
- Other plants produce their seeds inside fleshy fruits that then get eaten be an animal.
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Answer:
Animals disperse seeds in several ways. First, some plants, like the burr at left, have barbs or other structures that get tangled in animal fur or feathers, and are then carried to new sites. Other plants produce their seeds inside fleshy fruits that then get eaten be an animal. Burrs are dispersed with the mechanism known as epizoochory. It means dispersal by getting attached to the outside of animals. Burrs have barbs or other structures on them, which get tangled with the furs of the animals or with the clothes of people passing by. A bur (also spelled burr) is a seed or dry fruit or infructescence that has hooks or teeth. Bur-bearing plants such as Xanthium species are often single-stemmed when growing in dense groups, but branch and spread when growing singly.
Burs catch on the fur of passing animals or the clothing of people. The hooks or teeth can be irritants and very hard to remove from clothing, such as wool or cotton. Burs serve the plants that bear them in two main ways. First, they tend to repel some herbivores, much as other spines and prickles do. Second, they are mechanisms of seed dispersal by zoochory (dispersal by animals) and anthropochory (dispersal by humans). Plants with burs rely largely on living agents to disperse their seeds.
The flowers are small, green and inconspicuous. They form in clusters containing separate male and female flowers along slender branchlets and in leaf axils. Female flowers develop to become the fruit (burr).
The species is monoecious, with the flowers borne in separate unisexual heads: staminate (male) heads situated above the pistillate (female) heads in the inflorescence. The pistillate heads consist of two pistillate flowers surrounded by a spiny [involucre]. Upon fruiting, these two flowers ripen into two brown to black achenes and they are completely enveloped by the involucre, which becomes a [bur]. The bur, being buoyant, easily disperses in the water for plants growing along waterways. However, the bur, with its hooked projections, is obviously adapted to dispersal via mammals by becoming entangled in their hair. Once dispersed and deposited on the ground, typically one of the seeds germinates and the plants grows out of the bur.
The most famous example of biomimicry was the invention of Velcro brand fasteners. Invented in 1941 by Swiss engineer George de Mestral, who took the idea from the burrs that stuck tenaciously to his dog’s hair. Under the microscope he noted the tiny hooks on the end of the burr’s spines that caught anything with a loop – such as clothing, hair or animal fur. The 2-part Velcro fastener system uses strips or patches of a hooked material opposite strips or patches of a loose-looped weave of nylon that holds the hooks. Coolest application: Championship Velcro Jumping, first made popular in 1984 by David Letterman.