Trailing fleabane looks delicate, but it flowered through a drought
Trailing fleabane is small and appears delicate, but it is hardy and well defended. (Photo: Jeff Mitton)
Flower was once thought to repel fleas, a belief long-since debunked
According to the U.S. Drought Monitor, Boulder County was in severe drought in September and the beginning of October this year. On Oct. 14, I went up on Flagstaff Mountain to see what was blooming and to check the condition of some small cacti, Missouri foxtails.
The foxtails were shriveled and seemed to be shrinking into the earth, a common plight for cacti in drought conditions. But my attention quickly shifted to some delicate daisies鈥攖hese were the only flowers blooming in the prolonged drought.
The flowering species was flowering was Erigeron flagellaris. The plants were about 8 inches tall and had the typical daisy bloom with numerous slender, white petals radiating from a central yellow disc. Erigeron is a large genus in the family Asteraceae, commonly called composites, because each of the blooms is a composite of yellow disc florets in the center and white ray florets radiating.
Each "petal" is a ray floret, a flower that is solely female and fertile. Each of the disc florets is bisexual and fertile. An E. flagellaris bloom has 40 to 125 ray florets and even more disc florets.
In addition to seeds produced by both ray and disc florets, E. flagellaris reproduces asexually by producing stolons, stems that grow horizontally, touching ground at each node.
Erigeron flagellaris, or trailing fleabane, flowers and their mature seeds (Photo: Jeff Mitton)
Contact with the ground stimulates a node to grow a new cluster of roots that support the growth of upright stems, leaves and more flowers. This asexual reproduction creates a spreading clone that, under the best of conditions, resembles a mat. The proliferation of stolons suggests its common names, trailing fleabane and whiplash fleabane. Strawberry plants also spread with stolons, but gardeners usually call them runners.
The genus Erigeron has about 200 species, many of them in North America and all with the common name fleabane. The name, originally from Old English and first used in 1548, comes from the belief that the plant's smell would repel fleas from a dwelling. Plants were either burned or hung in sachets. Both belief and practice were dispelled long ago鈥攆leabanes do not banish fleas.
The Navajo were resourceful at finding preparations of plants that had practical uses for dyes and medicines, and they found a way to use the astringent properties released from crushed leaves of trailing fleabane. They would chew the leaves and then place the moist pulp directly on wounds to stop the bleeding.
Description of the scent of trailing fleabane is elusive. The website Southwest Colorado Wildflowers lists citations in which the scent has been described as spicy, camphor-like, ill-scented, mysterious and downright weird. Chemical studies of fleabanes shows that their fragrances come from essential oils, volatile liquids containing chemical compounds synthesized by the plant.
I was not able to find a study of the essential oil of trailing fleabane, but several other fleabanes have been studied, and all reveal a bewildering diversity of biologically active compounds. For example, a study of the essential oil in E. floribundus, which has the common names tall fleabane and asthma weed, has 85 biologically active compounds. Concentrations of the various compounds differ among fleabane species that have been studied, resulting in a diversity of fragrances.
The constituents in essential oils are undoubtedly expensive to synthesize, but many studies have shown that they contribute to the defense of the plant against herbivores, microbes and fungi. I see a parallel between the essential oils of fleabanes and the resins of pines, firs and spruces.
In fact, limonene is a component of both essential oils and resins. Laboratory studies have shown effective defensive activity of limonene in the oil of E. floribundus, and populations studies have shown that mountain pine beetles eschew ponderosa pines with high levels of limonene.
In summer months, as people camp, hike and generally play in the mountains, one often hears comments about the pleasant fragrance of stands of ponderosa pine, or a spruce and fir forest. But I have never noticed the smell of fleabanes. It is a certainty that herbivores such deer and rabbits note the smell and shun the plants; it is the primary defense of daisies.
The essential oils extracted from several fleabane species can be purchased on the web, but I am sure that sniffing a concentrated concoction of biologically active chemicals from a bottle and nasally inhaling in a field of fleabanes would be different experiences. Let's remember to go fleabane sniffing next summer.
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