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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]

Wild ginger's flowers are ~1-2" across, reddish-brown on the outside, cream colored on the inside, that develop from an axis at the junction of the two leaves (one flower per plant). The flower calyx consists of three triangular sepals with the long tips curled backwards; the tubular base of the calyx is divided into three pairs of chambers (six total) which contain the ovaries, twelve stamens, and six reddish-brown styles. Because the flowers are brown and occur right at ground level, they are easy to overlook and usually can only be seen by parting the leaves.

Asarum

Asarum canadense

wild ginger [Blooms: Apr/May-?]

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]

The flowerheads of swamp milkweed are erect, ~3" across, with 10-40 flowers; flowers are 1/4" across and typical milkweed morphology with pink petals and whitish hoods, but color can vary from pink to magenta; the central column is cream-colored and visible below the base of the hoods. The petals are reflected backwards but are not tightly pressed against the stem; the horns arch up and over the central column and taper to a sharp point.

Asclepias

Asclepias incarnata

swamp milkweed [Blooms: Jul-Aug]

The height of the stem and the leaves of Sullivant's milkweed are similar to common milkweed. Each plant produces 1-3 (total) flower clusters from the stem apex and adjacent leaf axils; each cluster is 2-4" across and has ~15-25 flowers, each ~1/2" across. The flower petals are pink to rich purple, with white bases; the hoods are usually noticeably lighter. The horns are laterally compressed (sickle-shaped) and their tips clearly overlap over the column.

Asclepias

Asclepias sullivantii

Sullivant's milkweed [Blooms: Jul-Aug]

Common milkweed's flowers arise from leaf axils, are 2.5-5" wide, hemispherical, and covered with typical 1/2" wide milkweed flowers ranging from light pink to reddish-purple; the petals, reflexed back around the base of the flower are darker than the hoods.

Asclepias

Asclepias syriaca

common 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]

Whorled milkweed's flowers are white, occurring in small (1-3") clusters that rise from leaf axils. Individual flowers are typical milkweeds (except for their color), 1/4" across; horns are sickle-shaped, petals are white or greenish-white. Once you recognize that this plant IS a milkweed, given its grass-like leaves in whorls, it is impossible to mistake it for any other local species.

Asclepias

Asclepias verticillata

whorled milkweed [Blooms: Jul-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]

Spanish needles flowers are 1/2" long and 1/4" across; they occur individually on the end of long peduncles. Each flower has 3-5 (sometimes zero) ovoid, yellow, petal-like ray florets around 12-27 yellow, tubular disc florets, each with five small lobes at their tips, 5 stamens, and a bifurcated style. Even in full bloom, the flowers look like buds. After fertilization, each flower produces needle-like, brown, four-angled, barbed seeds, each 1/2-3/4" long, that radiate in all directions from the base of the old flower.

Bidens

Bidens bipinnata

Spanish needles [Blooms: Aug-Sep]

Nodding bur-marigold's flowers usually have eight ray florets ("petals") that are elliptical; the flower is 1-2" across with the flower stem arising from leaf axil. Flowers nod down with age. The phyllaries at the base of the flowers are in two series — the outer phyllaries are of variable length but narrow, curly, and green; the inner phyllaries are almond shaped, as wide as the petals, and pale yellow-green.

Bidens

Bidens cernua

nodding bur-marigold [Blooms: Aug-Oct]

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]

Top — Crowned beggar-tick's (Bidens trichosperma) flowers in frontal view. Bottom — about twelve narrow, twisted phyllaries lie below the yellow flower sepals at the top of the stem.

Bidens

Bidens trichosperma

crowned beggar-tick [Blooms: Sep-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]

Wild hyacinth flowers have six slender, light blue to white tepals, six stamens with yellow anthers, and a slender style emerging from a green, egg-shaped ovary; the style has tripartite tip. The flowers are each supported by a slender pedicel. Wild hyacinth is very similar to prairie hyacinth (Camassia angusta), but the latter blooms later, is much less common, has thread-like bracts beneath each flower pedicel, 4-5 thread-like bracts on the flower stalk beneath the flowers, and differ (mostly) in details of the seed capsule. Prairie hyacinth has not yet been found in Jackson Park.

Camassia

Camassia scilloides

wild hyacinth [Blooms: May-Jun]

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]