Impatiens biflora Walter
Impatiens capensis, the orange jewelweed, common jewelweed, spotted jewelweed, spotted touch-me-not, or orange balsam, is an annual plant native to North America. It is common in bottomland soils, ditches, and along creeks, often growing side-by-side with its less common relative, yellow jewelweed (I. pallida).
Jewelweed plants grow 3 to 5 feet tall and bloom from late spring to early fall. The flowers are orange (or rarely yellow) with a three-lobed corolla; one of the calyx lobes is colored similarly to the corolla and forms a hooked conical spur at the back of the flower. Plants may also produce non-showy cleistogamous flowers, which do not require cross-pollination. The stems are somewhat translucent, succulent, and have swollen or darkened nodes (on only some plants). The seed pods are pendant and have projectile seeds that explode out of ripe pods when they are lightly touched, which is where the name 'touch-me-not' comes from; the pods instantly roll back into tight curled strips, launching the seeds. The leaves appear to be silver or 'jeweled' when held underwater, which is possibly where the jewelweed name comes from. Another possible source of the name is the color and shape of the bright robin's egg-blue kernels of the green projectile seeds.
Along with other species of jewelweed, the juice of the leaves and stems is a traditional Native American remedy for skin rashes, including poison ivy. Such use has been supported by at least one peer-reviewed study.
Impatiens capensis was transported in the 19th and 20th centuries to England, France, the Netherlands, Poland, Sweden, Finland, and potentially other areas of northern and central Europe. These naturalized populations persist in the absence of any common cultivation by people. This jewelweed species is quite similar to Impatiens noli-tangere, an Impatiens species native to Europe and Asia, as well as the other North American Impatiens. No evidence exists of natural hybrids, although the habitats occupied by the two species are very similar.
It is an herbaceous annual plant that often branches extensively. The round stems are glabrous and succulent. The alternate leaves are simple and have teeth on the margins.
The flowers are shaped in an unusual way, and bloom from early summer until frost kills the plant. Their spurs and bright colors aid in pollination. There are also cleistogamous flowers on the same plant. The mature fruits open at a slight touch, scattering the seeds.
Nectar spurs are tubular elongations of petals and sepals of certain flowers that usually contain nectar. Flowers of Impatiens capensis have these nectar spurs. Nectar spurs are thought to have played a role in plant-pollinator coevolution. Curvature angles of nectar spurs of Impatiens capensis are variable. This angle varies from 0 degrees to 270 degrees.
The angle of the nectar spur is very important in the pollination of the flower and in determining the most efficient pollinator. Hummingbirds are the main pollinators. They remove more pollen per visit from flowers with curved nectar spurs than with perpendicular nectar spurs. But hummingbirds are not the only pollinators of Impatiens capensis. Bees play an important role in pollination as well. Due to hummingbirds and bees, the pollination of Impatiens capensis is very high.
- Dickinson, T.; Metsger, D.; Bull, J.; Dickinson, R. (2004). ROM Field Guide to Wildflowers of Ontario. Toronto: Royal Ontario Museum and McClelland and Stewart Ltd. p. 197.
- "BSBI List 2007". Botanical Society of Britain and Ireland. Archived from the original (xls) on 2015-01-25. Retrieved 2014-10-17.
- Hilty, John (2016). "Orange Jewelweed (Impatiens capensis)". Illinois Wildflowers.
- Smith, Huron H. (1933). "Ethnobotany of the Forest Potawatomi Indians". Bulletin of the Public Museum of the City of Milwaukee. 7: 42.
- Motz; Bowers; Young; Kinder (2012). "The effectiveness of jewelweed, Impatiens capensis, the related cultivar I. balsamina and the component, lawsone in preventing post poison ivy exposure contact dermatitis". Journal of Ethnopharmacology. 143 (1): 314–318. doi:10.1016/j.jep.2012.06.038. PMID 22766473.
- Strausbaugh, P.D.; Core, E. L. (1964). Flora of West Virginia (2nd ed.). Seneca Books. p. 622. ISBN 0-89092-010-9.
- Travers, Steven E; Temeles, Ethan J; Pan, Irvin (2003). "The relationship between nectar spur curvature in jewelweed (Impatiens capensis) and pollen removal by hummingbird pollinators". Canadian Journal of Botany. 81 (2): 164–70. doi:10.1139/b03-014.
- Elemans, Marjet (2004). "Light, nutrients and the growth of herbaceous forest species". Acta Oecologica. 26 (3): 197–202. Bibcode:2004AcO....26..197E. doi:10.1016/j.actao.2004.05.003.
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