Filtered (357)
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]

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-?]

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]

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]

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]

Canada milkvetch flower stalks are ~6" long, covered by numerous (up to 75) cream-colored, tubular flowers (right side of image). Individual flowers are 1/2-3/4" long, slightly drooping, with five petals making up the tube (like an elongated pea flower) and a short (~1/4") cylindrical calyx of the same color with five thin, green teeth; the tip of the upper petal is reflected upwards. The fruits (left side of image) are short, pea-like legumes packed tightly along the flower spike.

Astragalus

Astragalus canadensis

Canada milkvetch [Blooms: Jun-Aug]

White wild indigo is a striking plant that puts up 3-6' tall spikes of white flowers; the flower spikes alone are up to 2' long. Each flower is ~1" long and across with a elongate, triangular bract at the base of the flower pedicel. A short (1/2"), tubular, bluish-green calyx with four triangular teeth encloses the base of a white typical pea-like flower with a forward-leaning banner (one petal, folded up and back along the midline) and a pair of wings (two petals) that enclose a keel (two petals); the keel encloses ten green stamens with orange anthers and the single style.

Baptisia

Baptisia alba

white wild-indigo [Blooms: May-Aug]

Stems of cream wild indigo terminate in 3-9" long flower spikes that sprawl laterally or arch. Each flower is ~1" long and across with a short (1/2"), tubular, light green to light purple calyx with 4-5 triangular teeth, a creamy-yellow (or very yellow) typical pea-like flower with a vertical banner (one petal) and a pair of wings (two petals) that enclose a keel (two petals); the keel encloses ten stamens and the single style. Flowers are held on ~1" long pedicels; at the base of each pedicel, a lance-shaped, 1/2-1" long bract is sessile on the flower stalk. This is our earliest-blooming wild indigo. Flower color, the profuse hairs, and the bracts at the base of each flower pedicel are sufficient to positively identify cream wild indigo.

Baptisia

Baptisia bracteata

cream wild-indigo [Blooms: May-Jun]

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]

River birch male (left) and female (right) catkins. Individual (highly modified) flowers are distributed over the surface of the catkins.

Betula

Betula nigra

river birch [Blooms: Apr-Jun]