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Overview

Comprehensive Description

Description

This native plant is a summer annual about 3-6' tall, branching frequently. The somewhat succulent stems are light green, glabrous, and glaucous. The alternate leaves are up to 4" long and 2" across. They are ovate, hairless, and serrated along the margins; their slender petioles are up to 2" long. From the axils of the middle to upper leaves, short racemes of 1-3 flowers are produced. Each flower is about 1–1¼" long, consisting of 5 petals, 3 sepals, and reproductive organs within the tubular corolla. This corolla is yellow, or less often cream-colored, and consists of the fusion (or near fusion) of the 5 petals and lower sepal. The lower sepal is petaloid; it defines the conical posterior of the corolla, which tapers to a tiny nectar spur that curls downward. The upper petal defines the upper lip (or hood) of the corolla, while the two lower petals form a pair of well-rounded lobes that are rather irregular and wrinkled. Two small lateral petals define the sides of the corolla opening, although they are difficult to see when the flowers are viewed from above. There are usually reddish brown spots within the interior of the corolla, although they are sometimes absent. The upper 2 sepals are light green and ovate in shape; they are located at the top of the corolla, rather than behind or underneath. Each flower dangles from a slender pedicel about ¾" long. The blooming period occurs from mid-summer to early fall and lasts about 2-3 months. Each fertilized flower is replaced by an ellipsoid seedpod up to 2" long. This seedpod is broadest toward the middle, tapering toward its tips; it has several dark green lines along its length. As the seedpod ripens, it splits open and ejects the seeds. The root system consists of a shallow branching taproot.
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© John Hilty

Source: Illinois Wildflowers

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Comments

Yellow Jewelweed is closely related to the more common Impatiens capensis (Orange Jewelweed). It is very similar in appearance to the latter species, except that its flowers are yellow, rather than orange. The tubular corolla of Yellow Jewelweed is broader toward its posterior, and its 2 lower petals are divided at the base, rather than fused together. Both of these Jewelweeds have attractive foliage and large interesting flowers that bloom over an extended period of time.
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© John Hilty

Source: Illinois Wildflowers

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Distribution

National Distribution

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

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Range and Habitat in Illinois

Yellow Jewelweed occurs occasionally in central and northern Illinois; it is less common or absent in the southern portion of the state (see Distribution Map). Habitats include muddy borders along ponds and streams (especially in wooded areas), swamps, openings in moist deciduous woodlands, and soggy thickets. Sometimes this species is cultivated in gardens. Faunal Associations
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Localities documented in Tropicos sources

Impatiens pallida Nutt.:
Canada (North America)
United States (North America)

Note: This information is based on publications available through Tropicos and may not represent the entire distribution. Tropicos does not categorize distributions as native or non-native.
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Quebec and Nova Scotia to Saskatchewan, south to North Carolina, Tennessee, and Oklahoma (Gleason and Cronquist 1991).

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Physical Description

Morphology

Leaves alternate; sepals three (the two upper are smaller than the third lower); flowers in axillary racemes, mostly pale yellow with brown spots, spur bent abruptly down and forward (Gleason and Cronquist 1991).

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Look Alikes

Lookalikes

Impatiens pallida is similar to the generally more abundant I. capensis. Impatiens capensis flowers are mostly orange-yellow, usually with reddish brown markings, with a slender spur (7-10 mm) curved gently forward; I. pallida flowers are mostly pale yellow, usually with reddish brown markings, with a short spur (4-6 mm) bent sharply down and forward (Schemske 1978; Gleason and Cronquist 1991; Tabak and von Wettberg 2008).

Impatiens pallida tends to grow on shadier sites than does I. capensis (Gleason and Cronquist 1991). Impatiens capensis is generally restricted to moist habitats adjoining lakes or rivers, but I. pallida is more tolerant of dry sites (Schemske 1978).

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Ecology

Habitat

Range and Habitat in Illinois

Yellow Jewelweed occurs occasionally in central and northern Illinois; it is less common or absent in the southern portion of the state (see Distribution Map). Habitats include muddy borders along ponds and streams (especially in wooded areas), swamps, openings in moist deciduous woodlands, and soggy thickets. Sometimes this species is cultivated in gardens. Faunal Associations
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Wet woods and meadows (Gleason and Cronquist 1991).

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Associations

Flower-Visiting Insects and Birds of Yellow Jewelweed in Illinois

Impatiens pallida (Yellow Jewelweed)
(Hummingbirds and most insects suck nectar; some bees collect pollen, as indicated below; flies also feed on pollen, as indicated below; observations are from Robertson)

Birds
Trochilidae: Archilochus colubris sn

Bees (long-tongued)
Apidae (Bombini): Bombus impatiens sn cp fq, Bombus pensylvanica sn fq; Megachilidae (Megachilini): Megachile brevis brevis cp np

Bees (short-tongued)
Halictidae (Halictinae): Lasioglossum versatus sn np

Flies
Syrphidae: Rhingia nasica sn fp np

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In a study in Illinois, Schemske (1978) found the primary pollinators of Impatiens pallida chasmogamous flowers to be the bumblebees Bombus vagans and B. impatiens, with rare visits by the (non-native) honeybee (Apis mellifera) and Ruby-throated Hummingbird (Archilochus colubris). Bumblebee pollination might be predicted based on the flower's large landing platform, broad sepal sac, and yellow color. Schemske (1978) collected a variety of small halictid and andrenid bees on I. pallida flowers, but viewed these bees as predominantly pollen and nectar thieves rather than effective pollinators because they showed a preference for male flowers, rarely contacted the stigma when foraging for nectar from female flowers, and usually foraged at just a single flower (never more than three) before leaving the area.

In his field studies of I. pallida at several sites in Illinois, Schemske (1978) identified a variety of herbivores feeding on this plant. The chrysomelid beetle Rhabdtopterus praetexus was a major leaf predator, sometimes causing complete defoliation through leaf skeletonizing. This beetle, which was observed mainly from early July to mid-August, fed almost exclusively on I. pallida and I. capensis. The sawfly Aglaostigma semiluteum was common throughout the growing season and probably restricted to I. pallida and I. capensis. Stem-boring larvae of the olethreutid moth Olethreutes agilana were common on both I. pallida and I. capensis (and are apparently restricted to these hosts) from mid-August until the end of the growing season. The arctiid moth Diacrisia virginica is known to be an extreme dietary generalist, but Schemske observed larvae only on I. pallida, on which it was present throught the growing season.

The aphid Dactynotus impatienscolens (probably an Impatiens specialist) was common on the peduncles and pods of I. pallida (and occasional on I. capensis). Galls on leaf midribs formed by larvae of by the cecidomyiid fly Lasioptera impatientofolia and on buds by Cecidomyia impatientis were common at one study site on both I. pallida and I. capensis. Nymphs of the pentatomid bug Acrosternum hilare were major seed predators of both I. pallida and I. capensis. Mortality of chasmogamous buds and flowers was primarily due to feeding by various grasshoppers and katydids.

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Life History and Behavior

Reproduction

Impatiens pallida has an unusual mixed mating system with cleistogamous (closed and self-fertlizing) flowers and chasmogamous (open, accessible to pollinators, and outcrossing) flowers on the same individuals (Tabak and von Wettberg 2008).

Chasmogamous flowers are strongly protandrous (i.e., male parts, the anthers, mature first). When the anthers dry, they fall off, exposing the female part, the stigma. Thus, male and female function are separated in time, preventing self-fertlization and promoting outcrossing. Flowers remain in the male phase for about five times as long as in the female phase, making the effective sex ratio of flowers on a plant heavily male biased (Schemske 1978). In cleistogamous flowers, nectaries are absent (because the flowers are closed, pollinators have no access and producing nectar to attract them would be a waste). Sepals, anthers, and the number of pollen grains produced are all reduced. Production of chasmogamous flowers ceases in early fall, but cleistogamous flowers are produced until plant death from frost (Schemske 1978).

The fruit of I. pallida is a 5-valved capsule which dehisces (opens to release seeds) elastically, projecting seeds up to 2 meters from the parent (Schemske 1978). Ovaries of chasmogamous flowers contain 3-5 ovules, cleistogamous flowers 1-5 (usually 2-3). Total development time from bud stage to pod maturation and dehiscence is quite variable, but averages 28-38 days for cleistogamous flowers and 37-48 days for chasmogamous flowers (Schemske 1978).

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Physiology and Cell Biology

Cell Biology

Cytology

2n=20 (Gleason and Cronquist 1991).

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Molecular Biology and Genetics

Molecular Biology

Statistics of barcoding coverage: Impatiens pallida

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 0
Specimens with Barcodes: 6
Species With Barcodes: 1
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Conservation

Conservation Status

National NatureServe Conservation Status

Canada

Rounded National Status Rank: N5 - Secure

United States

Rounded National Status Rank: N5 - Secure

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NatureServe Conservation Status

Rounded Global Status Rank: G5 - Secure

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Relevance to Humans and Ecosystems

Benefits

Cultivation

The preference is partial sun, wet to moist conditions, and soil that is loamy or mucky. Yellow Jewelweed also tolerates full sun, light shade, and mesic conditions (if it receives some protection from the afternoon sun). This species is a little more tolerant of dry conditions than Impatiens capensis (Orange Jewelweed). It grows rapidly from seed during the summer and can achieve an impressive size.
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Wikipedia

Impatiens pallida

Pale Jewelweed or Yellow Jewelweed (Impatiens pallida) is a flowering plant native to the United States. It grows in moist to wet soils, generally alongside the closely related Impatiens capensis, producing flowers from midsummer through fall. Along with other species of jewelweed or "touch-me-not", it is a traditional remedy for skin rashes, although controlled studies have not shown efficacy for this purpose.

Pollination[edit]

Nectar spurs are tubular elongations of petals and sepals of certain flowers that usually contain nectar. Flowers of Impatiens pallida have nectar spurs which are thought to have played a role in plant-pollinator coevolution. Most of the nectar spurs of Impatiens pallida are perpendicular but some of them are curved.[1]

These nectar spur flowers are either partially or completely pollinated by insects. The specific pollinator is determined by the curvature of the nectar spur. Since Impatiens pallida have perpendicular nectar spurs, bees are the main pollinators.[1]

References[edit]

  1. ^ a b Tavers,S.E., Temeles, E.J. and I. Pan. "The relationship between nectar spur curvature in jewelweed ( Impatients capensis)and pollen removal by hummingbird pollinators" Canadian Journal of Botany, 2003, vol. 81, pp. 164-170
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