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A small, somewhat shrubby tree up to 25' tall, although half that height is more common in Jackson Park (which is near the northern limit of its range). Devil's walking stick produces a terminal inflorescence of flowers (20+ ft. up). Flowers are small (1/4" long), white and are produced in umbels at the top of the tree. Devil's walking stick has flowers that are either male (bearing stamens) or female (bearing styles). The male flowers of devil's walking stick have prominent stamens and five white, triangular petals; the female flowers (shown here) look like rounded green buds with five stout styles emerging from the distal end.

Aralia

Aralia spinosa

devil's walking stick [Blooms: Aug-Sep]

Burdock has thistle-like, composite flowers with lavender to purple (rarely, white) disc florets but no ray florets; the surrounding bracts are green and strongly hooked.

Arctium

Arctium minus

burdock [Blooms: Jul-Oct]

Red chokeberry is a 6-12" tall shrub with multiple stems. Flowers are white with red tinge on the tips of the 5 petals; each flower is ~1" in diameter.

Aronia

Aronia arbutifolia

red chokeberry [Blooms: Apr-May]

Black chokeberry flowers occur in clusters of 7-12 near the margins of the shrub. Each flower is ~1/2" across with a reddish-green calyx with 5 short triangular lobes, 5 white, spoon-shaped, non-overlapping petals with rounded tips and a narrow base, 16-20 stamens with pink to rose-colored anthers, and 5 pale green styles, fused at their bases. The red glands on the upper leaf midvein and pink to rose-colored stamens are diagnostic of black chokeberry.

Aronia

Aronia melanocarpa

black chokeberry [Blooms: May-?]

Beach wormwood is an unusual plant 2-4' tall with characteristic, deeply dissected leaves. The flowerheads are 2-4 mm long and wide; each is composed of 5-20 outer disk florets that bear only stamens and 8-30 inner disc florets that possess both pistils and stamens. There are no ray florets.

Artemisia

Artemisia campestris

beach wormwood [Blooms: Aug-Sep]

Prairie milkweed produces one and a half to two inch balls of 30-100 greenish-white flowers in the axils of a few of the mid-stem and upper leaves; the flowers are supported on 1/2"-3/4" pedicels. Each flower is about 1/8" across and 1/4" long; the flowers are a variation on the typical (complex) milkweed morphology with 5 sepals, a 5-lobed corolla with 5 petals (often with purple blotches at their tips) that are reflected backwards to cover the top of the pedicel, 5 hoods without horns, and a short central column that rises above the hoods; there is a distinct gap between the bases of the petals and the crown. Seedpods are 4-5" long with a fat base (attached to the pedicel) tapering rapidly to a narrow tip. Prairie milkweed can be confused with whorled milkweed (Asclepias verticillata) — both occur in Jackson Park — but whorled milkweed has even narrower (grass-like) leaves than prairie milkweed, is a shorter plant, and has pure white flower that do bear horns.

Asclepias

Asclepias hirtella

prairie milkweed [Blooms: Jun-Aug]

Butterfly weed has clusters of 8-25 flowers, in various shades of orange with touches of yellow or red, that arise from the stems and leaf axils. Individual flowers have a typical milkweed morphology, with the petals reflexed backwards over the flower stalk and the complex corona protruding. The central column of the corona in A. tuberosa is always yellow regardless of the shade of the remainder of the flower. This is the only Illinois milkweed with orange flowers and has narrower leaves than all other local milkweeds except whorled milkweed (A. verticillata, which has white flowers).

Asclepias

Asclepias tuberosa

butterfly milkweed [Blooms: Jun-Sep]

Yellow mustard produces inflorescences at the apices of the stems; individual flowers are 3/8" across with four yellowish-green sepals, four yellow petals, six stamens with yellow anthers, and a single pistil with a robust style.

Barbarea

Barbarea vulgaris

yellow rocket [Blooms: Apr-May]

The flowers of devil's beggars-tick consist only of disc florets. The base of the flower is surrounded by 6-10 (usually eight) long phyllaries that extend beyond the flower's edge.

Bidens

Bidens frondosa

devil's beggar-tick [Blooms: Aug-Oct]

Individual flowerheads of false boneset are about a half inch long and surrounded by green phyllaries. Each floret (inset) consists of 7-21 creamy-white, tubular florets with five lobes at the tip, and a prominent divided style protruding from the corolla.

Brickellia

Brickellia eupatorioides

false boneset [Blooms: Jul-Aug]

American searocket's flowers are 3/8" across with four green sepals, four widely spread pale lavender to white petals, six stamens, and a pistil with a single white style.

Cakile

Cakile edentula

American searocket [Blooms: Jun-Aug]

Purple poppy-mallow has hairy flower pedicels ~6" long that arise from leaf axils; the flowers are ~2" across, brilliant magenta, with an hibiscus-like (but shorter) white central structure containing the stamens and styles. The five calyx lobes are very hairy, shorter than the petals, and light green; beneath the calyx are three very similar bracts.

Callirhoe

Callirhoe involucrata

purple poppy-mallow [Blooms: ?-Jul]

American bellflower has deep blue flowers with a white center; they are about 1" across. The petals are ruffled, the style is long, arching, with a trifid stigma on its tip.

Campanula

Campanula americana

American bellflower [Blooms: Jul-Aug]

Creeping bellflower stems produce a terminal raceme of blue to purple flowers up to a foot long with all the flowers nodding towards the ground and all on the same side of the stem. Individual flowers are 1-1.5" long, borne on a short pedicel with a narrow, lance-shaped bract at its base. Each flower is bell-shaped with five pointed, recurved lobes with hairy margins and five green sepals at its base. There are 5 short curly, yellow stamens and a long style that emerges from the bell; the style has a three-part stigma at its end.

Campanula

Campanula rapunculoides

creeping bellflower [Blooms: Aug-Sep]

Shepard's purse flowers bloom only at the stem's tip, which is continually elongating. Individual flowers are tiny (1/8") and have 4 greenish sepals, 4 rounded white petals, 6 greenish-yellow stamens, and a pistil with a single style. Flowers are followed by seedpods ("purses") that are 1/4" long, triangular, or heart-shaped, borne on ascending pedicels (lower part of image.)

Capsella

Capsella bursa-pastoris

shepard's purse [Blooms: Apr-May]

Hairy bittercress flower stalks with stem leaves. Here the three flowers bear seedpods (siliques - narrow cylinders) that elongate directly out of fertilized flowers (which continue bear petals).

Cardamine

Cardamine hirsuta

hairy bitter-cress [Blooms: April]

Pennsylvania bittercress flowers are 1/8" across with 4 light green, oblong sepals that cup the corolla, 4 white petals, 6 cream-colored stamens, and a single robust pistil with a flat, disc-shaped stigma. Fruits are erect, elongate (up to 1.25" long and 1 mm wide), flat-ended cylinders (siliques) containing a single row of seeds that emerge from the center of a fertilized flower while the petals persist.

Cardamine

Cardamine pensylvanica

Pennsylvania bitter-cress [Blooms: April]

At the apex of the blue cohosh stem is a floral panicle 1-3" long bearing 5-30 flowers. Individual flowers (insert) are about 1/3" (8 mm) across with six petal-like yellow-green sepals, and six stamens with yellow anthers in a ring around a central green ovary and style. The petals have been reduced to six green lobes at the base of the stamens, between the sepals.

Caulophyllum

Caulophyllum thalictroides

blue cohosh [Blooms: Apr-May]