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Bur(r) and Velcro brand fasteners

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.

he 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.

Burr Seeds – Animal Dispersal

A burr seed is a type of seed, or dry fruit, in which the seeds have hooks or teeth. The hooks can be irritating to remove, especially when they get attached to furs or clothes of passing animals or people. Some of the plants with burr seeds include burdock, ragweed and cicely. nimals 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. AcornsThe fruit is digested by the animal, but the seeds pass through the digestive tract, and are dropped in other locations. Some animals bury seeds, like squirrels with acorns, to save for later, but may not return to get the seed. It can grow into a new plant.

Wind dispersal

The kind of seeds which are often wind dispersed are smaller seeds that have wings or other hair-like or feather-like structures. Plants that produce wind blown seeds, like the dandelion shown in the video clip below, often produce lots of seeds to ensure that some of the seeds are blown to areas where the seeds can germinate.

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Floating in water

Many aquatic plants and plants that live near water have seeds that can float, and are carried by water. Plants living along streams and rivers have seeds that float downstream, and therefore become germinate at new sites. The size of the seed is not a factor in determining whether or not a seed can float. Some very large seeds, like coconuts, can float. Some small seeds also float.

A burr seed is a type of seed, or dry fruit, in which the seeds have hooks or teeth. The hooks can be irritating to remove, especially when they get attached to furs or clothes of passing animals or people. Some of the plants with burr seeds include burdock, ragweed and cicely. nimals 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. AcornsThe fruit is digested by the animal, but the seeds pass through the digestive tract, and are dropped in other locations. Some animals bury seeds, like squirrels with acorns, to save for later, but may not return to get the seed. It can grow into a new plant.

• The word “Velcro” is derived from the French “velour” (velvet) and “crochet” (hooks), so essentially “hooked velvet”.
• Velcro received a huge boost in popularity after being used by NASA on parts of astronaut’s space suits as well as used to allow astronaut’s to store things along the walls of their space craft. Because of this, similar to Tang, it is a common misconception that Velcro was invented by or for NASA.
• The company de Mestral started to sell his hook and loop fastener through, Velcro, has forbidden its employees to use the term “Velcro” due to the fact that their brand has become a genericized trademark, like Xerox or “Philips” screwdrivers. The employees are instead instructed to call their product a “hook and loop fastener”; “hook tape”; or “loop tape”.
• de Mestral’s patent for Velcro expire in 1978, after he was unsuccessful in updating it.
• Velcro hooks were later found to be able to be significantly strengthened by adding polyester to the nylon filaments.
• A two inch square piece of modern Velcro is strong enough to hang 175 pounds from.
• During the first ever human artificial heart transplant, Velcro was used to hold together the heart during surgery.
• The Velcro used by NASA today is made with Teflon loops, polyester hooks, and has a glass backing. They even use it in the astronaut’s helmets where a small strip functions as a nose scratcher.
• The U.S. army uses a near silent version of Velcro on their soldier’s uniforms. The version they use reduces the ripping noise by about 95% over traditional Velcro. Unfortunately you won’t see such Velcro for sale in the store anytime soon as the method of manufacturing this silent Velcro is currently classified.
• Velcro was not de Mestral’s first patented invention. At the age of 12 years old he invented a toy airplane that he subsequently patented. He also later patented a hygrometer, which is a device that measures humidity in the air, and an asparagus peeler.

Velcro produces commercially marketed fabric hook-and-loop fastener.

The word Velcro is a portmanteau of the two French words velours (“velvet”), and crochet (“hook”). Hook-and-loop fasteners consist of two components: typically, two lineal fabric strips (or, alternatively, round “dots” or squares) which are attached (e.g., sewn, adhered, etc.) to the opposing surfaces to be fastened. The first component features tiny hooks; the second features even smaller and “hairier” loops. When the two components are pressed together, the hooks catch in the loops and the two pieces fasten or bind temporarily. When separated, by pulling or peeling the two surfaces apart, the velcro strips make a distinctive “ripping” sound.

The hooks on a piece of Velcro	The loops on a piece of Velcro

The hook-and-loop fastener was conceived in 1941 by Swiss engineer, George de Mestral who lived in Commugny, Switzerland. The idea came to him one day after returning from a hunting trip with his dog in the Alps. He took a close look at the burrs (seeds) of burdock that kept sticking to his clothes and his dog’s fur. He examined them under a microscope, and noted their hundreds of “hooks” that caught on anything with a loop, such as clothing, animal fur, or hair. He saw the possibility of binding two materials reversibly in a simple fashion if he could figure out how to duplicate the hooks and loops. Velcro is viewed by some like Steven Vogel or Werner Nachtigall as a key example of inspiration from nature or the copying of nature’s mechanisms.

Originally people refused to take de Mestral seriously when he took his idea to Lyon, which was then a center of weaving. He did manage to gain the help of one weaver, who made two cotton strips that worked. However, the cotton wore out quickly, so de Mestral turned to synthetic fibers. He settled on nylon as being the best synthetic, which had several advantages. Nylon doesn’t break down, rot, or attract mold, and it could be produced in threads of various thickness. Nylon had only recently been invented, and through trial and error he eventually discovered that, when sewn under hot infrared light, nylon forms hooks that were perfect for the hook side of the fastener. Though he had figured out how to make the hooks, he had yet to figure out a way to mechanize the process, and to make the looped side. Next he found that nylon thread, when woven in loops and heat-treated, retains its shape and is resilient; however, the loops had to be cut in just the right spot so that they could be fastened and unfastened many times. On the verge of giving up, a new idea came to him. He bought a pair of shears and trimmed the tops off the loops, thus creating hooks that would match up perfectly with the loops in the pile.

Velcro is strong enough that a two inch square piece is enough to support a load of 79 kg.The strength of the bond depends on how well the hooks are embedded in the loops, how much surface area is in contact with the hooks, and the nature of the force pulling it apart. If Velcro is used to bond two rigid surfaces, e.g. auto body panels and frame, the bond is particularly strong because any force pulling the pieces apart is spread evenly across all hooks. Also, any force pushing the pieces together is disproportionally applied to engaging more hooks and loops. Vibration can cause rigid pieces to improve their bond. Full-body Velcro suits have been made that can hold a person to a suitably covered wall.

Velcro is the trademarked term usually used to describe any type of hook-and-loop fastening system. The material was developed in the mid-20th century, and is ubiquitous today. Velcro is popular in shoes and clothing, especially adaptive clothing designed for disabled or elderly wearers that cannot manipulate buttons and clasps. It is also heavily used in aerospace and military applications.

One lovely summer day in 1948, a Swiss amateur-mountaineer and inventor decided to take his dog for a nature hike. The man and his faithful companion both returned home covered with burrs, the plant seed-sacs that cling to animal fur in order to travel to fertile new planting grounds. The man neglected his matted dog, and with a burning curiosity ran to his microscope and inspected one of the many burrs stuck to his pants. He saw all the small hooks that enabled the seed-bearing burr to cling so viciously to the tiny loops in the fabric of his pants. George de Mestral raised his head from the microscope and smiled thinking, “I will design a unique, two-sided fastener, one side with stiff hooks like the burrs and the other side with soft loops like the fabric of my pants. I will call my invention ‘velcro’ a combination of the word velour and crochet. It will rival the zipper in its ability to fasten.”

Mestral’s idea met with resistance and even laughter, but the inventor ‘stuck’ by his invention. Together with a weaver from a textile plant in France, Mestal perfected his hook and loop fastener. By trial and error, he realized that nylon when sewn under infrared light, formed tough hooks for the burr side of the fastener. This finished the design, patented in 1955. The inventor formed Velcro Industries to manufacture his invention. Mestral was selling over sixty million yards of Velcro per year. Today it is a multi-million dollar industry.
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