How-To-Do-It Velcro & Seed Dispersal Ralph A. Postiglione The invention of Velcro is credited and produces fruit and seeds in the Downloaded from http://online.ucpress.edu/abt/article-pdf/55/1/44/45997/4449577.pdf by guest on 23 September 2021 to a Swiss scientist named George de autumn. The double seed is contained Mestral. In the 1940s he was hiking in the cocklebur, which has many and came home with cockleburs stuck coarse spined burs. Cocklebur is the to his trousers. Annoyed, he decided term used both for the plant and the to investigate this phenomenon under seed pod. the microscope. This examination re- Spermatophytes, like the cocklebur, vealed that the cockleburs were cov- represent the highest plant form since ered with small stiff hooks and his they create seeds by sexual reproduc- trousers were covered by soft fuzzy tion. A seed is a sexual reproductive loops. De Mestral seized upon this unit. To germinate, a seed requires efficient grasping device and invented warmth, oxygen and moisture. Fur- "hook and loop tape," known today ther, it requires ample space to germi- by its trade name Velcro (from the nate and grow into a mature plant. French words for velvet, "velour" and Seed dispersal, then, is very essential "crochet" for hook). in locating this free space. Mother na- Velcro is used to fasten hundreds of ture has enlisted the aid of wind, wa- !. .e items such as shoes, belts, pockets, ter, propulsive devices, etc. to accom- etc. However, as sages have often pro- plish the spread of seeds. claimed, there are no new ideas under the sun, only new correlations of orig- inal ones. Sages have also mused that Figure 1. Velcro "hooks" "nature had it first." With these Materials Needed showing and "loops" components. themes in mind, we will investigate Stereoscopic microscope or hand the subject of a man's "invention" lens, cockleburs, (or burdocks), wool based on one of nature's devices, swatches and Velcro(R) available from namely, Velcro, a marvelous "clasp- Velcro USA, Inc., 406 Brown Ave., vigorously move each side parallel and ing" mechanism, fashioned after the Manchester, NH 03108. in opposite directions. Again, have cockleburs. (Burdock may be used if them test the relative ease of separa- more readily available.) tion, as before, and record. If done The seeds of cocklebur plant (Xan- Procedure properly, the second trials will cause thium orientale) are bothersome. They 1. Have the students observe and more efficient closure and be more hook onto a person's clothing or in an make detailed sketches of both compo- difficult to pry apart. animal's fur. The range of Burdock nents of Velcro under the microscope and Cockleburs is in most of North or hand lens (see Figure 1). One side 3. Now have the students observe a America where there is sufficient of the Velcro will be in the form of cocklebur (see pod) attached to a small moisture. Being a herbaceous plant, it loops, while its companion side will be swatch of wool (other appropriate does not fare well in very dry climates. in the form of hooks. The loops are cloth may be substituted) under the It favors sandy ground where water is manufactured by a special weaving stereomicroscope. Again, a detailed available at shallow depths. It is a process. The hooks are made by cut- sketch should be made (see Figure 2). short-day plant and therefore flowers ting through the loops and mechani- Have them engage and disengage the cally shaking the resulting hooks into cocklebur and the wool several times disarray. under the stereoscopic microscope to demonstrate the insights of the origi- 2. Now have the students place the nal inventor of Velcro, de Mestral. Ralph A. Postiglione teaches at Great Velcro together and pull it apart six Neck South High School, Great Neck, NY times and record ease of separation as 4. After the students have studied 11020. to difficult, moderate or easy. Now, and sketched the specimens as out- with both sides attached, have them lined in steps one through three, have 44 THEAMERICAN BIOLOGY TEACHER, VOLUME 55, NO. 1, JANUARY1993 a class discussion focusing on the fol- lowing two areas: A. Methods of Seed Dispersal: How do each of the following aid in the spreading of seeds: cockleburs, wind, water, air and animals. B. Ideas that Have Borrowed t9g> from Nature: Birds and planes, fish and ships, (a) squid and jet motors, birds' feath- ers and the zipper, spinning projec- tile (football) and paramecium locomotion, explosive seed pods (touch-me-not) and jack-in-the- box, etc. To culminate this activity, have the students answer the fol- lowing: Downloaded from http://online.ucpress.edu/abt/article-pdf/55/1/44/45997/4449577.pdf by guest on 23 September 2021 1. Why is seed dispersal necessary C- < p for the survival of plant species? 2. How do the cockleburs aid in seed dispersal? 3. What is the advantage of two (c) enlarged 4X - approximately seeds found in each cocklebur? 4. What are the conditions neces- sary for seed germination? 5. Maple seeds occur in pairs and are transported by a winged Z structure called a samara. Dis- cuss this mode of seed dispersal. 6. Why are seeds excellent sources of human and plant nutrition? 7. The cocklebur produces two seeds in each of its fruits. One of the seed coats is much harder than the other, so that it usually (b) will germinate two years later than the first seed. How does this Figure 2. (a) wool "loops", (b) cocklebur plant and (c) cocklebur (involcre) with benefit the survival of this spe- "hooks". cies? * - II . 0 00 -. I 0 - 0 0 0S0 - -~~~~~e SEED DISPERSAL45 .