Touch-Me-Not family (Balsaminaceae)
Description: This wildflower 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.
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.
Range & Habitat: The native 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: The nectar of the flowers attracts the Ruby-Throated Hummingbird and bumblebees; the latter are especially common visitors. The caterpillars of various moths feed on the foliage, including Euchlaena obtusaria (Obtuse Euchlaena), Spilosoma latipennis (Pink-Legged Tiger Moth), Trichodezia albovittata (White-Striped Black), and Xanthorhoe lacustrata (Toothed Brown Carpet). The large seeds are eaten by various gamebirds, including the Ruffed Grouse, Ring-Necked Pheasant, Greater Prairie Chicken, and Bobwhite Quail. The White-Footed Mouse also eats the seeds. White-Tail Deer browse on the foliage.
Photographic Location: The photographed plants were growing along the back alley of a residential area in Urbana, Illinois.
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.