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An ornate pink flower with multiple levels of petals above a central core of projecting yellow stamens. This variant of Aquilegia vulgaris ("stellata" commercially called 'Nora Barlow') is a genetic variant that produces multiple stacked flowers (like the difference between a wild rose and commercial roses).

Aquilegia

Aquilegia vulgaris

common columbine [Blooms:May-Jun]

Japanese angelica tree may be mistaken for the (native) devil's walking stick, Aralia spinosa. However, the Japanese angelica tree (A. elata) has shorter (although quite substantial) compound leaves, sessile leaflets directly attached to the petiolule, a smaller inflorescence (about 2' tall rather than over 3'), and shorter, less intimidating spines on the trunk. Leaf venation (best viewed from the underside) is the best way to differentiate the two. In devil's walking stick, the pinnate leaf vein tips curve to form a sub-marginal vein parallel to the leaf margin. In the Japanese angelica tree, the leaf veins extend all the way to the margins of the leaf.

Aralia

Aralia elata

Japanese angelica tree [Blooms: Jul/Aug–?]

Spikenard is superficially similar to devil's walking stick (Aralia spinosa) but lacks the spiny leaves and stem of the latter. Both produce a terminal inflorescence of flowers (20+ ft. up). Unlike devil's walking stick, the flowers of spikenard are perfect; i.e., they have both male (stamens) and female (a stigma) parts. In this photo, both flower buds and flowers with prominent stamens are apparent.

Aralia

Aralia racemosa

spikenard [Blooms: Jul-Aug]

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]

Two thyme-leaved sandwort flowers, with leaves clearly visible on the stem on the left of the image. Easily overlooked as just another chickweed, thyme-leafed sandwort's petals are not deeply notched like chickweeds. The stems are 6-10" tall, erect or sprawling, dark purple, and covered with fine hairs. Tiny (4 mm) white flowers on 1/4" pedicels with backward-pointing hairs; flowers have five pointed, white, oblong petals; five hairy green sepals longer than the petals; ten white stamens with magenta anthers; a green central ovary; and three white styles. An exotic from Europe that prefers disturbed areas with minimal other vegetation.

Arenaria

Arenaria serpyllifolia

thyme-leaved sandwort [Blooms: Apr-Jun]

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-?]

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]

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]

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]

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]