Spotted touch-me-not is an erect native annual. Stems are succulent, somewhat translucent, 2 to 5 feet high, easily broken, branching occasionally.
Leaves are thin, egg shape with coarse broad teeth and slender long stalks. In dry conditions leaves can become thicker. Submerged in water, they take on a silvery sheen.
The inflorescence is a cluster of up to 3 flowers that rises from the leaf axils.
Flowers: Spotted touch-me-not has two types of flowers - chasmogamous, which open for fertilization and cleistogamous, which do not open and self-fertilize. The chasmogamous are 1 inch long flowers hanging on a long drooping freely moving stalk (pedicel) and the flowers have a curved nectar spur at the back end. The amount of curve is quite variable but can be as much as 270 degrees. The flower stalk has a small linear 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 seemed fused together in places, forming 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; the other two are a much lighter color and seen on the top of the corolla behind the upper lip. Five stamens with yellowish anthers are united around the single pistil and the assemblage is tucked up under the upper lip.
These 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 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 inserting a hummingbird's 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.
Habitat: Touch-me-nots are plants of moist places with full to 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 adapt to drier soils when there is sufficient rainfall. They are somewhat drought tolerant with plant size and flower production affected.
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 capensis, means 'of the Cape of Good Hope, South Africa', but this was a mistake by the plant author who was under the impression the species was native there. You will see this plant listed with an older, now replaced, species name -I. biflora. The author name for the plant classification - ‘Meerb.’ is for Nicolaas Meerburgh (1734-1814) Dutch botanist who was director of the botanical garden in Leiden and most known for his 5 volumes of Portraits of Rare Plants (Afbeeldingen van zeldzame gewassen.) The alternate old common name “Wild Balsam” is derived from the Latin family name for the species, BALSAMINACEAE.
Comparisons: Spotted Touch-me-not has orange flowers with red-brown spots. The spur on the back bends underneath and forward and upward and is usually parallel to the flower but not at a right angle downward like the Pale Touch-me-not (Impatiens pallida), which is also slightly larger, however, there are variations depending on the maturity of the flower.
Above: 1st photo - The two pale green small sepals are visible on top of the angled upper lip of the corolla. Note also, the small bract halfway back on the flower stalk. 2nd photo - The third sepal is the same color as the corolla petals and forms the large tube and nectar spur at the back of the flower. Note the line of separation of this sepal from the corolla petals in front of it.
Below: 1st photo - A typical egg shaped leaf with broad teeth. 2nd photo - The separation of the two lower corolla petals is clearly seen in this bottom view, as it is in the large photo at the bottom of the page.
Below: The five stamens with yellow anthers are united around the single pistil and tucked up under the upper lip. Anthers shed pollen first, then wither and the stigma of the pistil becomes receptive to pollen from another flower. Drawing from Britton, N.L., and A. Brown. 1913. An illustrated flora of the northern United States, Canada and the British Possessions. 3 vols. Charles Scribner's Sons, New York.
Below - Touch-me-not seed dispersion: 1st photo is the seed capsule approaching maturity. When the capsule is ready, touching it with slight pressure will cause the plant material inside to suddenly form a twisted coil (2nd photo) and disperse the seeds to quite a distance.
Below: Touch-me-not can occupy extensive areas in a year with adequate moisture as this photo indicates. This is a section of the Eloise Butler wetland on Aug. 27, 2009.
Notes: Spotted Touch-me-not is indigenous to the Garden area. Eloise Butler catalogued it on May 25, 1907. The plant is widely distributed in the United States and Canada, absent only in the SW and the far north. It is in most counties of Minnesota except for a few in the drier SW corner. It is native to the state and can become invasive. For a story about its invasive nature in the Garden during Eloise Butler and Martha Crone's tenures as curator read this section from the History of the Wetland.
The only two species of Impatiens native to Minnesota are I. capensis and I. pallida, Pale Touch-me-not.
Eloise Butler wrote of Jewelweed: "Every inch of space on low, moist soil not held firmly by tufted meadow grasses and sedges is occupied by the Wild Balsam. [Note: “Wild Balsam” is derived from the Latin family name for the species, BALSAMINACEAE and in English as the Touch-me-not Family.] The smooth, glossy stem has a translucent appearance, and its joints are swollen, affording another proof, of course, that rheumatism is induced by dampness! The leaves are thin and delicate. When dipped in water, their under-surfaces appear to gleam like quicksilver, an appearance due to tiny hairs that catch the water and enmesh air bubbles. The hairs keep the pores that are abundant on the under side of the leaves from being clogged with water. Some water beetles show the same phenomenon when they dive; but, in their case, the air bubbles supply them with the requisite oxygen during the period of immersion. Little girls are familiar with the plant as Jewelweed. By means of the curved nectar spur, they hook the flowers in their ears and are fine ladies, for the nonce, with gold ear-drops. The most common species of Balsam has flowers usually spotted with brown, of varying shades of orange and yellow, and sometimes pink or white. This is called Impatiens biflora. I pallida has larger, pale yellow, often unspotted flowers, with stouter spurs. The term Impatiens refers to the nature of the seed-vessel, the origin of another common name, touch-me-not. If you gently press the plump, ripe seed-pod between your thumb and forefinger you will be startled by its breaking up into writhing, worm-like pieces, and by the seeds snapping out several feet into space." Published Aug 20, 1911, Minneapolis Sunday Tribune.
Lore and Uses: The Ojibwa used the thick juice that comes from a stem, when broken, to apply to skin rashes and rubbed it on the head for a headache. The application to relieve skin irritations was also known in Britain.
Toxicity: The juice of Impatiens capensis is somewhat toxic to animals. The sac in the spur of the flower contains a liquid. Modern testing has shown that the juice contains chemicals that are considered fungicides and therefore would be slightly poisonous to grazing animals.
Thoreau wrote in his journals: "Touch-me-not seed vessels, as all know, go off like pistols on the slightest touch, and so suddenly and energetically that they always startle you, though you are expecting it. They shoot their seed like shot. They even explode in my hat as I am bringing them home."
References: Plant characteristics are generally from sources 1A, 32, W2, W3, W7 & W8 plus others as specifically applied. Distribution principally from W1, W2 and 28C. Planting history generally from 1, 4 & 4a. Other sources by specific reference. See Reference List for details.
Identification booklet for most of the flowering forbs and small flowering shrubs of the Eloise Butler Wildflower Garden. Details Here.
Friends of the Wild Flower Garden, Inc. Text and photos are by G. D. Bebeau unless otherwise credited. "www.friendsofthewildflowergarden.org"