Form and Function

How is Edelweiss able to thrive in its environment due to its form and function?

             As mentioned in the Home page, Leontopodium alpinum lives in an alpine environment, suggesting it enjoys cool, rocky, and sunny environments. Therefore, just like any other organism, it must develop certain structural components to be able to live and multiply in its environment. Edelweiss has done this in several ways, and the examples that follow should help you to understand how each individual constituent works with the others to create a stable, optimal, and thriving lifestyle for the Edelweiss plant. It is important to recognize that, overall, Leontopodium alpinum has many typical plant parts, including a stem, leaves, primary xylem, and primary phloem to name a few. Edelweiss has the unifying traits of all Angiosperms, but the structure and function discussed below are mostly unique to this organism.
A close-up of the Edelweiss florets and bracts. (Courtesy of Dr. Amadej Trnkoczy)

             One of the most unique structural elements that Edelweiss has developed over time is “white filamentary hair that cover the bracts” (thick leaves) of the plant (Vigneron et al 2005). Upon examining this structure with an electron microscope, it is believed that the Edelweiss plant is one example of a minimal number of plants to exhibit an "internal photonic structure" (Vigneron et al 2005). This observation is incredibly astounding to biologists because it implies that the plant can absorb ultraviolet light. Many plants are unable to absorb ultraviolet light, includuing Brassica rapa (turnip), Cucumis sativus (cucumber), and Glysine max (soybean). The main question explored in the article is whether the bracts or the filamentary hairs are responsible for the absorption of this ultraviolet light, seeing as without this absorption, such strong rays of light could be very damaging to the cells of the plant, causing mutations, similar to radiation in humans. (Vigneron et al 2005). The tremendously interesting result from research is that the “wooly” part of the flower protects the plant from ultraviolet light without hampering its ability to absorb visible light, which is truly remarkable.

            Returning to the discussion of filamentary hairs and their photonic structure, it is important to recognize how ridiculously small these hairs are—fractions of a micrometer, if that is even fathomable. The hairs themselves are “tubular internally, with parallel striations” (Glover and Whitney 2009). As rare as this structure is in plants, it is not completely absent from other organisms, and can be found in the Monarch butterfly, Predaceous diving beetle, and the feathers (that change colors) in birds (Vigneron 2005). These hairs are fully responsible for the absorption of damaging light rays, and are found on the bract of the plantthe thick-leafed part that is often mistaken for the petal of the flower. This hair also protects against dehydration, particularly because of the cold and windy alpine environment (see Habitat), and keeps the internal cells at an optimal temperature for functioning properly.

            While Edelweiss is indeed a flowering plant (Angiosperm), the flower itself is not what one would initially perceive upon looking at the plant. The “wooly ‘petals’” are not actually part of the flower, but instead are a type of leaf called a bract, as mentioned earlier. The flower component of the plant is, in retrospect, “incredibly small and inconspicuous,” and are essentially the yellow freckles noticeable in the center of the wooly leaves (Johnston 2012). These flowers sometimes remain hidden under the hairs and the blooming period can span up to a week, beginning first in the outer ring and then near the flower’s head (see Reproduction). While the hair-covered parts of the plant are perhaps the most striking and obvious, many of the leaves are not actually covered in this protective hair, most likely because they are located under the larger mass of the plant and are thus already protected from the strong ultraviolet light (Johnston 2012).

            Similar to many other members of the Asteraceae family, the “flower’s anthers are hidden in a mast where the stigma rests and eventually contacts these pollen-covered anthers, after which the pollen sticks to the stigma and is able to be carried with it” (Johnston 2012). Flower disks are considered to be the circular clusters of yellow flowers that are visible in the Edelweiss plant. These disks can grow almost anywhere, including on parts of the stem, and live out their lifespan as a group, turning a brown color after their blooming cycle is complete. Leontopodium alpinum is widely protected because if the flower heads are picked from the plant on more than one occasion, it loses the ability to propagate by seeding; it is therefore known as a “short-lived perennial” (Johnston 2012).

            Just like many other plants, compounds found in Edelweiss have been used for medicinal purposes for many years. One such example is leoligin, a metabolite from the roots of the plant that is able to "inhibit intimal hyperplasia in human saphenous veins"—thickening of the vein in response to trauma or healing (Reisinger et al 2008). While this is just one example, few people are aware that many of the small parts of a plant, like metabolites, can be so important structurally and functionally.

            The overall structure of Leontopodium alpinum is not unique, but the bits and pieces that connect the entire plant prove to be very much one-of-a-kind. While many typical plant parts exist, there are several components of Edelweiss that cannot be found in any other organism. All of these components work together to help Leontopodium alpinum thrive in the dry, cold, and rough environment it lives in, and it is important to understand that no one factor ensures the health and prosperity of this brilliant plant.

            I hope this page has helped you highlight the unique aspects of Edelweiss and how these components connect to the plant’s lifestyle. These adaptations have a direct impact on the plant's mechanisms for reproduction and dispersal.

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Please see the References page for information about where this data was aqcuired.

This page was written by Lizzy Wlodyga