Common Name: Spotted Jewelweed, Touch-me-not, Orange Balsam, Silverweed, Snapweed – There are several postulated explanations for the metaphorical assignation of the term ‘jewel’ to this weedy plant. The most prevalent is that the beaded dewdrops that form on the leaves scintillate as if bejeweled. The orange red flowers are maculated; ‘spotted’ distinguishes this species from the pale jewelweed, which has pale yellow blossoms.
Scientific Name: Impatiens capensis – The genus name is the Latin word for impatient. This refers to the seed pods of the plant that burst open at the slightest touch – hence the common name ‘touch-me-not.’ The species name is an erroneous toponym meaning ‘of the cape’, referring to the Cape of Good Hope at the southern tip of Africa where they were thought to have originated. The plant has been also listed as I. biflora, I. fulva, I. noli-tangere or I. nortonii.
Potpourri: Jewelweed may be the epitome of oxymoronic botanical descriptive names; a jewel is not a weed and a weed is not a jewel. It is called a weed because it grows in well-watered waste areas like ditches and gullies, crowding out other species with its rapid growth and proliferating fecundity. It is not a weed in the sense that a weed is undesirable. It is also a jewel. Laying aside the etymology of the name jewelweed that is based on its visual appearance, it is a jewel in the sense that it is something desirable and esteemed. It is one of the more notable medicinal herbs of forest or field; it is therefore a jewel of a weed – QED.
There is not a singular explanation for the origins of the name jewelweed; different references offer three alternative hypotheses. The first is that the contrasting, multi-hued and aesthetically appealing flowers dangle like jeweled pendants as if from a verdant earlobe. This is especially true of the spotted jewelweed, but even the pale jewelweed has an orchid-like asymmetrical balance that would earn a similar sobriquet. The second proffered rationale ascribes attribution to the jewel-like silvery iridescence of the leaves when submerged. Jewelweed leaves are resistant to water penetration so that when they are submerged, they have a shimmering argentous appearance; the alternative common name silverweed is descriptive of this effect. The third and most plausible explanation for the jewelweed moniker is that the beads of water that collect on the leaves and stem are like little jewels. This is best described by William Hamilton Gibson, a 19th Century naturalist and writer in the book Strolls by Starlight and Sunshine. After dismissing the jewel-like flowers and silvery leaves, Gibson settles on the most compelling of observations: “Let us lay our lantern amid the succulent stems here by the brook. What a lavish display of gems! Every leaf among the lush, translucent canopy, though apparently dry at high noon, now dripping low in listless fashion, and bordered with its pendant array of pure limpid diamonds, a spectacle such as Aladdin might have awakened beneath his supernatural lamp, but which finds few parallels in natural fields.” He attributes this to “minute glands along the edge of the leaf” that “begin to show themselves at dusk and at midnight have reached their full splendor.” There is a scientific explanation of this observed phenomenon. Nastic movement is the differential growth rate between the dorsal and ventral sides of the leaves, jewelweeds droop at night, becoming horizontal during the day. As observed by Gibson, the drooping results in some internal hydrostatic pressure that forces liquid exudate out of the pores in the leave in small jewel-like droplets that is fully manifest after darkness has set in. That seems a most reasonable explanation; beaded dewdrops are the likely origin of the name ‘jewelweed.’
The proliferation and differing explanations of the origins of the common name jewelweed are paralleled in the five different scientific names of the species. Historically, the most commonly used scientific name was Impatiens biflora, which translates literally as ‘impatient, two-flower.’ This is very appropriate in describing the spotted jewelweed, which actually has two kinds of flower. In addition to the enticing red and yellow tubular blossoms, there is a sub-rosa secondary flower. The primary flower is intended for the attraction of pollinators which brush against the stamen to transport pollen for the fertilization in the ovary of the pistil in the course of penetration for the extraction of nectar. The primary flower is especially configured so as to attract hummingbirds; it has a nectar spur that extends from the back of the flower ideally suited to their long, narrow beaks. The high energy biological cost of maintaining the complex system of dazzling blossoms containing aromatic nectar is necessary and sufficient for genetic diversity. Flowers that open for fertilization are called chasmogamic. The secondary flowers, conversely, are called cleistogamic. They are self-fertilizing and therefore do not need to open, a shy, unnoticed cousin of the flamboyant red and yellow efflorescence.
The ‘biflora’ arrangement is not all that uncommon (the ubiquitous violets also have two flowers) as it is a very successful evolutionary adaptation. The perfect, if obscure, cleistogamic flower requires significantly fewer nutritional resources, thereby facilitating survival in the lean times. The downside is there is no genetic randomness that successful evolutionary adaptation requires. In having both types of flower, the jewelweed has both genetic diversity and a more reliable reproductive capacity – it has evolved for survival. Two of the other scientific species names have some relevance: I. fulva is from the Latin word for ‘tawny,’ an apt description of the hue of the primary flower; I. noli-tangere is from the Latin phrase ‘no –touch,’ which warns against the explosive ejection of its impatient seeds. So why is the official scientific name I. capensis? As explained above, this means ‘of the cape’ and is the result of an erroneous belief that the plant was from the Cape of Good Hope in southern Africa. The laws of International Code of Botanical Nomenclature mandate that the first time that a plant is officially identified and named as a new species takes precedence over all subsequent names. The alternative would result in pointless logomachy and confusion. When Nicolaas Meerburgh, the Dutch curator of the Leiden Botanical Garden, named the plant for its faux-African provenance in 1775, it was ever after to be so.
The jewelweed is a very successful plant, generally crowding out competitors with densely thicketed growth. In part this is because of the unalloyed success of its self-pollinating flowers in never wasting away for want of pollen transport. But a more important measure is the inimitable means of seed ejection, the basis for the genus name Impatiens and for the sobriquet ‘touch-me-not.’ The fruit produced by the jewelweed is a capsule which contains the reproductive carpels of the plant. As is the case with most capsules, it is dehiscent, which means that it opens to release the seeds. The unique feature of plants of the genus Impatiens is the structure of the capsule. It has five distinguishable longitudinal segments called valves that are attached at the apex and at the base of the capsule. When ripe, the encapsulated seed pod splits along the valve joints and the apex and base are elastically drawn together by coiled attachments resulting in forceful ejection of the seed. The plenitude of seeds and the considerable projection distance promote jewelweed reproduction.
Poison Ivy (Toxidendron radicans) and stinging nettle (Urtica dioica) are among the more noteworthy banes of the peripatetic hiker. The former causes long term dysphoria, the latter an immediate crescendo of prickles. Jewelweed is (somewhat) of an antidote for both and not atypically found in the same wet area habitat; it is there when you need it. The etiology of the use of I. capensis for pruritus is the herbal practices of the Native Americans. The University of Michigan Native American Ethnobotany Database lists 45 separate uses for jewelweed; many but not all include dermatological treatments. The Cherokee rubbed it on “ivy poisoning” and the Menominee prescribed the washing of poison ivy rashes and nettle stings with a bath made from crushed jewelweed. The practice was adopted by the early settlers to the extent that the treatment made it into the King’s American Dispensary in 1898: “The bruised plants or the juice applied to parts poisoned by rhus (erstwhile genus name of poison ivy) give prompt relief. It also gives relief from effects of stinging nettle.” More recent scientific investigation has revealed more dubious and qualified results. The original work is from a 1958 article by R. A. Lipton in the Annals of Allergy entitled “The use of Impatiens biflora in the treatment of Rhus Dermatitis.” This was a report of the application of jewelweed preparations to 115 poison ivy sufferers of whom 108 “responded most dramatically.” A follow up study by a different group of researchers in 1980 found, conversely, that jewelweed had no effect whatsoever.
A definitive clinical evaluation M .V. Abrams et al was published in 2012 in the Journal of Ethnopharmacology entitled “The effectiveness of jewelweed, Impatiens capensis, the related cultivar I. balsamina and the component, lawsone in preventing post poison ivy exposure contact dermatitis.” (Lawsone is one of the chemicals found in jewelweed). The trial involved the intentional application of urushiol oil (the culprit ingredient in poison ivy) to six locations on the sacrificial arms of a number of volunteers. Five of the six locations were then treated with five different palliative remedies: Jewelweed mash; Jewelweed extract; a soap made from the Jewelweed extract; plain water; and commercial dish soap. The sixth was left untreated as a control – reaction to urushiol oil is variable among individuals. The findings provided some insight into the mixed findings of previous studies. Jewelweed mash was found to be effective, but the jewelweed extract was not. Soap made from jewelweed extract was effective, but no more effective than commercial dish soap. The conclusion is self-evident on reflection: Since poison ivy rash is caused by oil, then using a soap to break down the oil will prevent it from penetrating the epidermal layer. This can be accomplished by finding a patch of Jewelweed and mashing it up to take advantage of its inherent soapiness due to the saponins compounds that it contains. However, if urushiol oil is not removed in about an hour, the autoimmune response manifest as an itchy rash will result. Beyond poison ivy and stinging nettles, the medicinal benefits of jewelweed for other purposes are still under review. The Native Americans had many other uses for the plant including treatment by the Iroquois for renal disorders, as a diuretic, as a febrifuge, and for sore eyes and by the Cherokee as a gastrointestinal and gynecological aid. Recent research has revealed the presence of numerous chemical compounds in jewelweed that have demonstrable medicinal benefits in laboratory testing. Lawsone, mentioned above, has known anti-fungal and anti-microbial properties; it is also found in henna which has been used for millennia in the Middle East to treat skin disorders. It also contains anthraquinone and spinasterol, both known anticarcinogenic compounds. Perhaps there is more jewel in jewelweed.