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The petals (actually, sepals) of Canada anemone flowers are rounded; the pistillate cone in the center of the flower is approximately hemispherical and less than 10% of the flower width. The fruit is a round cluster of flattened seeds. The five-lobed leaves of Canada anemone are superficially similar to those of wild geranium (Geranium maculatum) but are sessile, not borne on petioles. Canada anemone is the commonest flower in Jackson Park in the late spring and summer.

Anemone

Anemone canadensis

Canada anemone [Blooms: May–Sept]

Thmbleweed flowers are borne on long (1-2') stalks; each flower is about 3/4" across with 5 pointed white petals-like sepals that often remain partially closed; the green pistillate cone in the center of the flower is about twice as long as it is wide (i.e., a tall gumdrop) ~20% of the flower diameter. A. canadensis may also have pointed petals, but the cone in the center of the flower is hemispherical (a short gumdrop). Thimbleweed (A. cylindrica) is best distinguished from tall anemone (A. virginiana) by the shape of the leaflets — A. cylindrica has leaflets with a wedge-shaped base with the lobes radiating out from the base, while A. virginiana has a rounded leaflet base with toothed distal margins.

Anemone

Anemone cylindrica

thimbleweed [Blooms: Jun-Jul]

Wood anemone produces slender green, hairy stems that bear either alternate leaves or (more typically) a whorl of three compound leaves at the apex of the stem; the 5 cm tall flower stalk arises from the center of the whorl. The flower stalks each bear a single white (sometimes pink) flower 1" across with 4-9 petal-like sepals and 30-60 stamens with white anthers surrounding numerous simple pistils.

Anemone

Anemone quinquefolia

wood anemone [Blooms: Apr–May]

Tall anemones have leaves on long petioles (like A. cylindrica). The petals (actually, sepals) of the flowers are pointed (like A. cylindrica); the pistillate cone in the center of the flower is approximately hemispherical and >1/3" across, about 20% of flower diameter. Thimbleweed (A. cylindrica) is best distinguished from tall anemone (A. virginiana) by the shape of the leaflets — A. cylindrica has leaflets with a wedge-shaped base with the lobes radiating out from the base while A. virginiana has a rounded leaflet base with toothed distal margins.

Anemone

Anemone virginiana

tall anemone [Blooms: Jun–Jul]

The main stems and some of the lateral branches of dogbane produce panicles of flowers 1-3" across on their tips; the central flowers in the cluster open first. Individual flowers are tiny — 2-3 mm across and 3-5 mm long, bell-shaped, with a fluted edge produced by the 5 white pointed petals. The stamens are shorter than the petals and curve toward the center of the flower, forming a cone over the ovoid stigma.

Apocynum

Apocynum cannabinum

common dogbane [Blooms: Jun-Aug]

Spectacular and unmistakable red and yellow, columbine's bell-like flowers hang aperture down from an arching flower stalk; the four elongate, parallel spurs point up while the stamens and style emerge from the bottom of the flower. This is the only columbine native to Illinois.

Aquilegia

Aquilegia canadensis

red columbine [Blooms: Apr-Jun]

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]

Bearberry produces small clusters of 2-15 flowers from the tips of the previous year's twigs. Individual flowers are urn- or bell-shaped with a constricted opening ringed by five short lobes, 1/2" long and wide; they have a five-lobed flattened calyx, a white or pink corolla, 10 stamens, and a single style none of which protrude outside the corolla. The flower pedicels are about 1/4" long, red and have a narrow bract at their base. The fruit is a spherical drupe 1/4-1/2" across, initially whitish green but red at maturity.

Arctostaphylos

Arctostaphylos uva-ursi

bearberry [Blooms: April]

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]

Flowerheads of pale Indian plantain. These plants can be to 9' tall and commonly reach 6+ feet; the stem is pale green to purple with a whitish cast. The flat-topped apical flowerhead is shaped like an inverted pyramid made up of small (1/8x3/8") tubular, cream-colored flowers with five disc florets surrounded by five bracts.

Arnoglossum

Arnoglossum atriplicifolium

pale Indian-plantain [Blooms: Jun-Aug]

Prairie Indian plantain flowerheads are tubular, 3/16" x 3/8", greenish white to reddish white, with five disc florets surrounded by five bracts with white keels (which distinguishes them from pale Indian plantain flowerheads).

Arnoglossum

Arnoglossum plantagineum

prairie Indian-plantain [Blooms: Jun-Jul]

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-?]

Mugwort's Inflorescence consists of leafy spikes covered with inconspicuous flowerheads, initially whitish-green, later yellowish- or purplish-green; the flowerheads are egg-shaped, very small (1/8" across) and bear only disc florets (ray florets absent).

Artemisia

Artemisia vulgaris

mugwort [Blooms: Jul-Oct]