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Cow parsnip flowers are present in 6-8" wide, flat umbels (like Queen Anne's lace) that arise from the central stem or from leaf axils. Beneath each flower cluster are four or more needle-like, fuzzy green bracts; the bracts fall off after the fruit begins to form. Individual flowers are 1/4" across with five white petals that are notched at their tips; in flowers on the edge of an umbel, one petal is visibly larger than the other four. A somewhat lumpy, cream-colored, hairy ovary occupies the center of the flower from which arise two short styles; five stamens with pale yellow anthers arc laterally from under the ovary. Each fruit is heart-shaped, flattened, and contains two seeds.

Heracleum

Heracleum sphondylium

cow parsnip [Blooms: May/Jun-?]

Dame's rocket flowers occur in clusters (racemes) of up to 30. Each flower is 3/4-1" across and long, with a long, narrow, tubular, pinkish-green calyx composed of four long narrow sepals. The calyx opens through a narrow throat into four rounded, pinkish-purple (sometimes white) petals; the six pale yellow stamens and the multiple styles poke to various degrees out of the throat. Stems, leaves, pedicles, and the flower calyxes are all downy or hairy. The fruits are long (up to 4"), narrow, ascending, downy cylinders (siliques, typical of mustards) filled with flattened, oblong seeds. The flowers are very phlox-like, but phlox flowers have five petals, and dame's rocket only has four; phlox leaves are opposite on the stem (not alternate) and are narrower.

Hesperis

Hesperis matronalis

dame's rocket [Blooms: Apr-May]

Halberd-leaved rose-mallow is a striking wild hibiscus, usually found near water, whose stems can get 6' tall. Flowers arise from leaf axils, are trumpet-shaped, up to 5" across, with five rounded, partially overlapping white to pink petals; a central columnar reproductive structure covered in creamy-white stamens (with reddish-tan anthers) in whorls, and a terminal divided style with five recurved tips, each bearing a stigma shaped like the head of a pin. Behind the corolla is a green calyx with five lobes, and ~12 rod-like, curved, green bractlets below the calyx that taper to sharp points. The throat of the flower is a deep reddish-purple or rose pink. Seed pods form within the persistant sepals; the seed pod is divided into five sections filled with fuzzy brown seeds. The three-lobed (halberd-shaped) or five-lobed (maple leaf shaped) leaves distinguish this species from other rose-mallows. (Only swamp rose-mallow, Hibiscus moscheutos, also occurs in Jackson Park.)

Hibiscus

Hibiscus laevis

halberd-leaved rose-mallow [Blooms: Jul-Aug]

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]

Wild hydrangea canes produce a flat terminal panicle 3-6" across with 100-500 flowers of two kinds — small, fertile flowers filling most of the area and a few, sterile pseudo-flowers around the margin that are 3-4 times larger than the flowers in the center and seem to function only as an advertisement for pollinators. The central, fertile flowers are about 1/4" across with a green calyx made of five separate sepals; five greenish-white or cream petals about 1/8" long; 8-10 stamens with long filaments and oblong, white anthers; and a pistil bearing two styles with knob- or club-like stigmas. The sterile, outer pseudo-flowers have 3-4 fused petal-like, white bracts (or sepals; sources differ) with a central structures that visually is reminiscent of stamens or styles; the pseudo-flowers persist long after the inner flowers have been fertilized and have produced a two compartment seed pod that is ribbed and bears a pair of tiny horns (the styles) on its upper end. Wild hydrangea is relatively rare in northern Illinois; in Jackson Park it prefers wooded area by walking paths.

Hydrangea

Hydrangea arborescens

wild hydrangea [Blooms: Jun-Aug]

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]

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]

American water-willow produces long (up to 6") peduncles from some of the upper leaf axils that have clusters of flowers on their tips. Individual flowers are 3/4" across with a short, tubular, 1/4" long, green calyx with five teeth and a tubular corolla with four lobes — an upper lobe with a shallow V-notch, two widely spreading lateral lobes, and one lower lobe at right angles to the other three. Both the lateral and lower lobes are folded downward along their midlines, producing a U-shaped cross-section. All of the lobes are white or pale purple with a darker splotch on the end of the upper lobe and dark purple spots along the midline of the lower lobe and at the base of the lateral lobes. There are two stamens, each with a dark brown pair of anthers posed in front of the upper corolla lobe and a single, narrow, white style running along the midline off the upper lobe and protruding beyond its upper boundary.

Justicia

Justicia americana

American water-willow [Blooms: Jun-Aug]

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]

Field peppergrass tems produce racemes of flowers near their apex; flowers near the top of the raceme are the youngest with older flowers (and later seed pods) further down the inflorescence. The flowers have a calyx of green or purple-green, lance-like sepals, four white, spoon-shaped petals, six stamens, and a single style. The fruits are flattened pods oval in outline with the remnants of the style protruding from a notch in the end (rather like field pennycress, Thlaspi arvense); each seedpod contains two seeds. This is an easy plant to overlook if only because it look like the weed that it is.

Lepidium

Lepidium campestre

field peppergrass [Blooms: May-?]

Peppergrass (aka, Virginia pepperweed) is a weedy, 1.5' tall, rather bushy plant. The flower spikes (racemes) are 2-4" long with tiny (<1/8") white apical flowers forming a larger inflorescence. The flowers have four oblong green or tan sepals with a white edge, half the length of the petals, alternating with four white, triangular petals. There are two stamens with yellow anthers and a stubby (0.2 mm tall) style on a green ovary. Below the flowers, the flower spike is covered with 1/8" wide seedpods on (relatively) long stalks, reminiscent of a bottlebrush; the seedpods are oval with an apical notch (much like half-sized versions of field pennycress (Thlaspi arvense) seedpods) containing two seeds. This species is native to the U.S. The stubby cylindrical inflorescences are and the triangular petals alternating with shorter sepals are diagnostic and distinguish pepper grass from field peppergrass (Lepidium campestre).

Lepidium

Lepidium virginicum

peppergrass [Blooms: Oct-Nov]

Round-headed bush-clover present stout, tall (2-5') green columns in the middle of open habitats. The stem is unbranched below the midpoint (except at the inflorescences), round in section, grooved, and densely covered in white hairs. At the apex of the main stem and on some of the side stems are slightly elongated balls of flowers 3-5" long and half as wide with numerous clover-like white flowers nearly hidden among leafy bracts; brown flowerheads and stalks may persist through winter. Each clover-like flower is about 1/4" wide and 1/2" long with five petals, one large vertical upper petal ("standard") and two perpendicular side petals ("wings") are visible; the other two petals (forming the keel) are hidden from view by the wings. There are ten stamens, all but one with their filaments fused together, and a single style with a small stigma. The petals are white with a patch of reddish-purple near the junction of the three visible petals. The fruit is a fuzzy pod less than 1/4" long containing a single seed. Round-headed bush-clover is a perennial with a tap root that may go down two meters into the soil.

Lespedeza

Lespedeza capitata

round-headed bush-clover [Blooms: Aug-Sep]

Ox-eye daisy is an aggressive plant that was introduced to the U.S. in the 19th century and is now thoroughly naturalized. Flowerheads occur singly at the apex of the stem on a long flower stalk. The flowerheads are about 1.5-2" across with 15-35 brilliant white, oblong ray florets and 120-200 yellow disc florets in a central, flattened disc about 3/4" across. The ray florets are fertile (they bear pistils with a split stigma) while the disc florets have both pistils and stamens. The disc florets are tubular with five tiny lobes at the apex, five stamens, and a single style with a bifurcated tip. The underside of the flower has numerous bracts in 2-4 layers; the bracts are green with purple to brown edges that outline each bract.

Leucanthemum

Leucanthemum vulgare

ox-eye daisy [Blooms: May-Jul]

Despite its common name, summer snowflake starts blooming in the spring (late April), not the summer. It is an introduced species, native to Europe and west Asia, similar in appearance to snowdrops (Galanthus nivalis) but larger. The leaves are exclusively basal, up to 12" long and an inch wide, flattened, arching, dark green, sheathing the base of the stems which may be the same length but are usually shorter than the leaves. The flowers dangle from the tips of hollow flower scapes in groups of 2-5, subtended by a single green, sword-shaped, spathe-like bract. Each flower has three sepals and three petals (white, pointed, with a yellowish-green spot near their tips), six stamens with orange anthers, and a single style with a green tip and a tiny stigma. Summer snowflake is toxic if ingested (like many lilies).

Leucojum

Leucojum aestivum

summer snowflake [Blooms: Apr-May]

Liriope spicata is native to east and south-east Asia but was introduced to North America (specifically Illinois and Alabama) as a ground cover — it is perennial and evergreen. A single plant grows 6-18" tall and 12-24" across; it does not tolerate foot traffic. The arching leaves are dark green, grass-like, 18" long and 1/4" across, with minutely-serrated edges and parallel venation. The inflorescence is a spike-like, brownish-white rachis covered with off white or pale lavender flowers. The flowers have six elongate oval tepals, six stamens with yellow anthers, and a stubby white style about the same length as the stamens. The fruit is a berry that is initially green, turning blackish as it matures.

Liriope

Liriope spicata

creeping lilyturf [Blooms: Aug-Sep]

Amur honeysuckle flowers occur in near-sessile pairs arising from leaf axils; there is a 2 mm long flower stalk (the thickness of a U.S. five cent coin). The corolla is about 1" long and tall, white or cream-colored, consisting of four fused, vertical upper lobes and a single lower lobe at 90° to the upper lobes; this geometry creates an opening through which protrudes five long stamens with yellow anthers and the solitary pistil with a green, knobby stigma. Outer surfaces of the flower are hairy. The fruit is a 1/4" diameter, shiny-red, spherical berry, usually in clusters of 2-4, that looks rather like a large current. The berries are mildly poisonous. The berries of amur honeysuckle are very similar in appearance and distribution to the berries of Morrow's honeysuckle (Lonicera morrowii), but the berries of the former are sessile while the berries of the latter are attached to 1/2" long pedicels. In addition, the leaves of amur honeysuckle have elongated tips while the leaf tips of Morrow's honeysuckle are relatively blunt; only amur honeysuckle has sessile flowers. Please don't plant this in your garden — too often, it escapes.

Lonicera

Lonicera maackii

amur honeysuckle [Blooms: Apr-Jun]