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Flower-of-an-hour flowers are borne singly on hairy flower stalks that arise from the leaf axils; the flowers are 2" across, with five partially-overlapping petals that are white or pale yellow with deep purple bases. Sepals are pale green, translucent, and membranous with deep purple, hairy veins. The numerous stamens are borne on a "staminal column" that surrounds the base of the style; the filaments are maroon and the anthers are golden yellow. The single style is white where it rises above the staminal column and is divided at the tip into five knobby stigmas.

Hibiscus

Hibiscus trionum

flower-of-an-hour [Blooms: Jul-Sep]

Virginia waterleaf stems are variable in color (green, reddish-green, or reddish-brown) and up to 2' tall. Each upper stem has at their tips one or two clusters (cymes) of 8-20 flowers that is 1-2" in diameter on a 4" stalk (peduncle); the central flower opens first. Individual flowers are 1/4-1/2" long, roughly bell-shaped, white, pink, or light violet in color. Flowers have a green, hairy calyx with five long, narrow teeth fringed with widely-spaced, stout hairs; a tubular corolla with five equal lobes at the open end; five stamens covered with long hairs along their lower half, with anthers initially yellow that later turn dark brown; and a single lavender style with a white, bifurcated tip. Both the stamens and the style are 30-50% longer than the corolla lobes and extend well beyond their edges.

Hydrophyllum

Hydrophyllum virginianum

Virginia waterleaf [Blooms: May]

Orange jewelweed flowers are about 1" long and 1/2-3/4" wide, conical, bright, shiny orange with reddish or brown streaks or dots and with a posterior sac and nectar spur that are actually a modified sepal; the flowers hang from drooping pedicels like floral mobiles with two more-conventional-looking sepals as attachments. The morphological center of the flower is the point where the pedicel joins the two obvious sepals at the top of the flower. A single petal forms the upper lip of the flower; two petals form the lateral sides; and two partially fused petals form the two-lobed lower lip. A cluster of stamens with white anthers hangs from the upper lip near the aperture; there is a single pistil. The shade of orange and the extent of the darker dots and streaks are highly variable (from absent to covering the flower). The fruit is a pea-like seed pod that splits lengthwise to fling the seeds away from the plant.

Impatiens

Impatiens capensis

orange jewelweed [Blooms: Jul-Nov]

Ivy-leaved morning glory is a sprawling, green to reddish vine up to 6' long covered with long, white hairs. Flowers arise from leaf axils on very short (1/4") stalks; they are funnel-shaped, ~2" across, blue-violet with a white throat, with five stamens with white anthers and a single style with a three-lobed stigma. The calyx is about 1/2" long, divided into five long, narrow teeth. Individual flowers only last a few hours. The seed capsule has three compartments and is hairy. Sepals are relatively very long and narrow, unlike common morning glory, where the sepals are short and triangular. Ivy-leaved morning glory is also native to Central America and its history of introductions is probably similar to common morning glory, Ipomoea purpurea.

Ipomoea

Ipomoea hederacea

ivy-leaved morning-glory [Blooms: Aug-Sep]

Small white morning glory is a vine 3-8' long, covered in scattered white hairs. The flowers are much smaller (1" long and 3/4" across) than most other Jackson Park morning glories, pentagonal rather than circular in outline, white, and shallowly lobed. The flowers consist of five lance-like sepals about 4 mm long, the funnel-like corolla, five stamens with a white filament and pinkish-purple anthers, and a single style with a knobby or bifurcated stigma. Fertilized flowers produce a spherical, hairy seed capsule about 1/2" in diameter nestled in the five sepals. Unlike the other two morning glories in Jackson Park, small white morning glory is native, but uncommon in northern Illinois.

Ipomoea

Ipomoea lacunosa

small white morning-glory [Blooms: Aug-Sep]

Wild sweet potato is a twining vine that can reach 20-30' long, completely covering the adjacent vegetation. The flowers are funnel-shaped with five shallow lobes, 2.5-3" across, white with a reddish-purple or rosy throat. There are five stamens of different lengths with filaments up to an inch long and whitish-pink anthers; there is a single whitish style with a two-lobed stigma. The flowers tend to bloom early in the day, later if cloudy. Individual flowers are short lived but this plant is a prodigious producer of blooms; it is the largest morning glory in Jackson Park. The "sweet potato" is a modified root up to 20" long and weighing 30 pounds; it is edible, but only barely.

Ipomoea

Ipomoea pandurata

wild sweet-potato [Blooms: Jun-Aug]

Common morning glory is a vine up to 10' long with alternate, heart-shaped (never lobed), smooth-margined, almost as wide as long. The stem is green or reddish-purple, covered with long hairs; it twines around adjacent vegetation and objects. Cymes of 1-5 flowers arise from some leaf axils; they sit at the tip of about 4" long pedicels. The flowers are 2-3.5" wide, funnel-shaped, usually deep purple or pink, less commonly blue or white, a single style with a three-lobed stigma, and five stamens. Sepals are relatively short, hairy, and triangular unlike ivy-leaved morning glory (I. hederacea), where the sepals are long and narrow. Other morning glories (Ipomoea sp.) usually have lobed leaves; the superficially-similar bindweeds usually have arrowhead-shaped leaves, not heart-shaped. Common morning glory has sepals that are short and triangular, unlike ivy-leaved morning glory where the sepals are relatively very long and narrow. Common morning glory is native to Mexico; it was introduced to England by 1621, then introduced from England to North America around 1700 as an ornamental (Fang et al., 2013), where it rapidly escaped cultivation.

Ipomoea

Ipomoea purpurea

common morning-glory [Blooms: Aug-Sep]

Black walnut has separate male and female flowers on the same tree (often the same branch). The male florets occur on 3-6" long, dangling, green, cylindrical catkins that arise from the leaf axils of one-year-old branchlets; the florets are 1/8" across and are comprised of a short, tubular calyx with 2-6 lobes and 15-40 stamens with greenish-yellow or purplish anthers. The female florets occur in groups of 2-5 on short spikes that arise from the tips of the current year's new branchlets; these florets are also about 1/8" across but are comprised of a short, tubular calyx with four lobes, a stout, green ovary covered with sticky hairs, and a pair of stout, bushy styles with red-tinged stigmas. The female florets are wind pollinated; the trees are self-fertile if cross-pollination does not occur. Fertilized female florets develop into globoid nuts about 2.5" long and 2" across that initially retain the styles; the nuts are solitary or in pairs. The thick husk turns from green to yellowish-brown to black as the fruit matures. The nuts cannot germinate unless they are exposed to 90-120 days of cold winter temperatures.

Juglans

Juglans nigra

black walnut [Blooms: May?-Jun]

Dudley's rush culms (stems) vary from 8-30" tall, unbranched except for the inflorescence, light green, hairless, and round in section. At the base of the culm are one or two 12" long, 1 mm wide, flat basal leaves. The sheath of the leaves clasps the bottom inch or two of the culm; they may be light green, light brown, or tan; at the top of the sheaths are tiny, thick, cartilaginous ear-like lobes less than 0.5 mm wide. At the culm's apex is a branched inflorescence with 6-80 flowers. At the base of the inflorescence are 1-3 narrow bracts; at least one of the bracts extends beyond the inflorescence. Individual flowers are about 1/4" across, solitary at the end of short branches, each with six 4-5 mm long tepals in two layers, six stamens, and a pistil with a singe style; they are wind pollinated. The tepals spread somewhat as the fruit is developing.

Juncus

Juncus dudleyi

Dudley's rush [Blooms: May-Jun]

Soft rush can be 2-4' tall, often growing in clumps of culms. Culms terminate in an inflorescence 3/4-4" across and an underlying bract 4-12" long that looks more like an extension of the culm than a leaf so the inflorescence looks like it is growing out of the side of the culm. Individual flowers are 2-3.5 mm long with three lance-shaped sepals, three lance-shaped petals, three stamens, and single style emerging from a central ovary; the flowers are wind pollinated. Color of these elements varies from green to brown depending on stage in the life cycle; sepals, petals, and the ovary/capsule are all about the same length at maturity.

Juncus

Juncus effusus

soft rush [Blooms: May-Jun]

Path rush (aka, slender path rush, poverty rush) is a native perennial 4-12" tall. It occurs singly or in dense tufts; the culms are light to medium green, slender, and unbranched. The leaves are considered basal by some sources, alternate by others, slender (about 1 mm across and up to 10" long), medium green, hairless, and flat with margins that tend to roll upwards. Fertile stems bear a branched inflorescence at their tips that is 1/2-3" across, bearing an umbel-like cluster of up to ten solitary flowers (never larger groups); at the base of the inflorescence is three slender, leafy bracts up to 4" long (the larger are longer than the inflorescence) that form a "V". Individual flowers have six lance-shaped, light green tepals, 3-5 mm long; six stamens; and an ovary (later a seed capsule) with a three-part, feathery style. Fertilized flowers produce an ovoid seed capsule nestled in the crown-like tepals, often with a tiny point at its tip; it is never longer than the tepals. The seed capsule later splits in three segments, releasing the tiny (0.5 mm) seeds.

Juncus

Juncus tenuis

path rush [Blooms: ?-Jun]

Torrey's rush is 2-3' tall, with robust stems that are deep green, hairless, and circular in cross section; each stem bears 2-5 alternate leaves and 1-3 basal leaves. The central stem branches rapidly at its tip; each branch ends in a spherical flowerhead about 1/2-3/4" across. The lowest flowerhead in the array sits above a very long, thin bract (main image). There may be up to 23 flowerheads in the array. Individual flowerheads are composed of 25-100 florets that each have six stamens, a narrow ellipsoid ovary with a 3-part stigma (center of insert), and six tepals (sepals and petals) in two layers; all tepals are green, bract-like, lance-shaped, and 3-6 mm long. The flowerheads are more bristly than flower-like in appearance. The flowers are wind-pollinated. After fertilization, flowerheads turn brown and look very spikey.

Juncus

Juncus torreyi

Torrey's rush [Blooms: Jul-Aug]

Kochia's greenish-yellow flowers are 4-5 mm across. Perfect flowers have five green, bluntly-triangular sepals that develop wings along their outer face, no petals, five stamens each with two large yellow or pink anthers, and a divided style; pistillate flowers lack the stamens. The flowers are wind-pollinated. The fruit is a flattened, five-lobed, winged capsule nestled in the sepals that contains a solitary seed. ITIS says that the accepted name for this plant is Kochia scoparia; World Flora Online claims the proper binomial is Bassia scoparia.

Kochia

Kochia scoparia

kochia [Blooms: Jul-Aug]

Two-flowered cynthia is a yellowish-orange dandelion-like composite flower consisting of only ray florets. Each of the 25-60 ray florets is elongate with a truncated tip with five tiny teeth; the stamens are orange and the styles have bifurcated tips. The basal leaves are hairless, up to 7" long and 2" across, with a broad, rounded tip; the base of the leaf narrows into winged petioles that clasp the stem. The margins of the leaves are nearly toothless. The 1-2' tall stems arise from the center of the basal rosette. One to six 1" wide flowers sit on stalks that emerge from an upper stem leaf axil where one or two lance-shaped leaves clasp the stem; unusually, only two flowers are open at any one time. The yellow-orange color is distinctive; most other dandelion-like flowers are yellow.

Krigia

Krigia biflora

two-flowered cynthia [Blooms: Jun-?]

Canada lettuce gets up to 8' tall (and is quite impressive when it does), but is usually considerably shorter. On larger plants, the inflorescence is an apical pyramid 2' tall covered with dandelion-like flowerheads; on smaller plants the flowerheads may be more scattered. Flowerheads are yellow or "dirty orange," a bit over 1/4" wide with a 1/2" long calyx and 15-22 ray florets with toothed tips, each with five stamens and a bifurcated style; there are no disc florets. Seeds are oval, flattened, and attached to a tuft of threads (like a dandelion). Small Canada lettuce plants are superficially similar to prickly lettuce (Latuca serriola), but the latter has large spines on the underside of the main veins of the leaves and seeds that are attached to the tuft of hairs by a beak twice as long as the seed.

Lactuca

Lactuca canadensis

Canada lettuce [Blooms: Jul-Sep]

Prickly lettuce flowerheads dandelion-like, a distinctive pale lemon-yellow color, and 1/4-1/2" across; there are about 20 ray florets with squared, serrated ends (with five teeth), five stamens with yellow anthers, and a bifurcated style whose base is surrounded by the anthers. The seeds are attached to the tuft of hairs by a beak up to twice as long as the seed. Prickly lettuce is superficially similar to Canada lettuce (Latuca canadensis), but the latter has no spines on the leaves and seeds that are attached to a tuft of hairs by a beak no longer than the seed. Prickly lettuce is the closest wild relative to domestic lettuce (L. sativa).

Lactuca

Lactuca serriola

prickly lettuce [Blooms: Jul-Sep]

Wood nettle plants may be either monoecious (separate male and female flowers on the same plants) or unisexual (only male or only female flowers). Male flowers are produced from branching cymes 4" long that arise from the leaf axils; female flower are produced from branching cymes, also 4" long, localized near the apex of the stem. Male flowers are small (1/8" across), consisting of five narrow, greenish-white sepals and five stamens; there are no petals but there is a vestigial pistil. Female flowers are about the same size (1/8" across) with four green sepals (two larger, two smaller) that look like tiny leaves with undulating edges and an ovary with a long, white, vertically-oriented J-shaped style that tapers to a point. The female flowers are wind-pollinated. The fruit is circular in outline but very flattened, green turning black with maturation, on a short winged stalk; the remains of the style are attached at the free end of the fruit.

Laportea

Laportea canadensis

wood nettle [Blooms: Aug-Sep]

Duckweed is a tiny, floating flowering plant (one of the smallest in the group) that is present on the lagoons and Columbia Basin from May through October. The flower is highly reduced — about 1 mm across consisting of a cup-shaped scale, a pair of tiny stamens, and a single pistil; I have never observed it. (The flowers are rarely produced — most reproduction is vegetative.) The combination leaf and stem is oval, 2-5 mm long and 1.5-3.5 mm across with a single rootlet up to 2 cm long dangling from the underside. Unless you have a good magnifying glass or microscope, further detail will not be useful.

Lemna

Lemna minor

duckweed [Blooms: ?]