Plants of the Eloise Butler Wildflower Garden

Pale touch-me-not is an erect native annual. Stems are succulent, somewhat translucent, 3 to 6 feet high, easily broken, branching occasionally.

Leaves are thin, egg shape with coarse broad teeth and slender long stalks.

The inflorescence is a long-stalked cluster of up to 3 flowers that rises from the leaf axils.

Flowers: Pale touch-me-not has two types of flowers - chasmogamous, which open for fertilization and cleistogamous, which do not open and self-fertilize. The chasmogamous has 1 to 1-1/4 inch inch long flowers hanging on a long drooping freely moving (pedicel) stalk and the flowers have a curved nectar spur at the back end that curves downward and sometimes then forward. This spur is shorter than that on I. capensis which curves forward more. The stalk has a small ovate to lanceolate shaped bract in mid-stalk. The flower stalk is attached just above the mouth of the corolla where one petal and three sepals come together. Flowers have 5 petals that seem fused together in places. These form the upper lip projecting out like a hood, two laterals and two larger lower lips which flare outward. There are 3 sepals, with the larger forming the cone of the back of the flower and the nectar spur and showing itself at the base of the corolla between the two large lower petals; the other two are a much lighter color and seen on the top of the corolla behind the upper lip. Five stamens with white anthers are united around the single pistil and the assemblage is tucked up under the upper lip.

The flowers are sexually dichogamous, that is, with the male and female parts maturing at different times, thus avoiding something nature does not like - self pollination. The male parts are ready first and the anthers are ready for pollen release for only a twenty-four hour period, then the anthers are dropped and the female stigma is exposed. The receptive phase then follows when the stigma can receive pollen from a flower that still has pollen for release but that phase is very short - average of four hours according to experiments that have run.

The cleistogamous flowers are found singly in the lower leaf axils and require only three weeks to mature. These are usually produced later in the season. These are only 1 to 2 mm in diameter. These flowers produce seed when, through stress or other climatic conditions, the regular open flowers are few or cannot be pollinated. Also, since the type of pollinator required for the open flowers, due to its deep nectar sac, is quite limited, and also since the plant is an annual, cleistogamous seed production insures that the species will re-seed.

The fruit is a pod that when mature will explode and expel the seed some distance - hence the common name of "touch-me-not" (see Thoreau's notes at bottom of page). Seeds are longer than wide, brown with lighter ridges and usually number 3 to 5 per pod. The cleistogamous flowers also form seed pods but contain fewer seeds. Hummingbirds and large bees are the prime pollinators. By a hummingbird inserting its long tongue into the curved nectar spur, the spur is pushed away with each lick of the tongue and then the spring-like action of the pedicel brings the flower back toward the bird causing the anthers or the stigma to contact the back portion of the birds bill, thus transferring pollen. [see Mobility of Impatiens capensis flowers: Effect on pollen deposition and hummingbird foraging by Hurlbert, Hosoi, Temeles and Ewald, Spring 1996 published in Oecologia.] For details on the mechanism that releases the seeds explosively, see this article. (pdf) Another article that covers in detail the research on the open and closed flower types in this species is Jewelweed's Sexual Skills, by Donald M. Walker, University of Wisconsin, in Natural History, Vol. 91 #5. and also papers in Evolution, Vols. 34, 38, 41. While all articles deal specifically with I. capensis, the methods are the same in I. pallida.

Habitat: The Jewelweeds are plants of deciduous woods and moist places with full to partial sunlight, although this species seems to prefer only partial sunlight. They are true annuals. Because of this their abundance varies from year to year - and they are found only in moist areas of the Garden during drier years, otherwise they can grow in drier soils with adequate rainfall.

Names: The genus name impatiens is Latin for "impatient" referring to the characteristic of the seed to explode from the dry seed head. The species name pallida refers to "pale," the color of the corolla. The alternate old common name “Wild Balsam” is derived from the Latin family name for the species, BALSAMINACEAE.

The author name for the plant classification - ‘Nutt.’ is for Thomas Nuttall (1786-1859) English botanist who lived and worked in America from 1808 to 1841. On his many expeditions he collected many species including some that had been originally collected by Lewis and Clark but lost by them on their return journey. He was indefatigable as a collector but incompetent in many practical matters. Washington Irving wrote of him in Astoria “Mr. Nuttall was a zealous botanist - forgetful of everything but his immediate pursuit.” He revised and added to French botanist Francois Andre Michaux’s 3 volume North American Sylva.

Comparisons: Pale Touch-me-not has pale yellow flowers with few spots. The spur on the back bends at a right angle downward, but usually not very far underneath the corolla and not far forward but not then upward like the Spotted Touch-me-not, I. capensis, however, the position of the spur will vary depending on the maturity of the flower. Flowers are also larger than I. capensis. Both the Spotted and the Pale Touch-me-nots are in the Woodland Garden but the Spotted is much more prolific and invasive. At the end of summer the spotted can be seen all over the marsh area in certain years.