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The flowers of hedge bindweed are 2-3" long, formed from five white or pink fused petals; the throat of the trumpet is light yellow (less extensive than in field bindweed). The flowers are ephemeral, often lasting only a single day.

Calystegia

Calystegia sepium

hedge bindweed [Blooms: May-Sep]

Nodding thistle is another heavily-defended exotic thistle, accidentally introduced to the U.S in the early 1900s. Solitary flowerheads are borne on long (up to 2'), whitish peduncles densely covered with short hairs. The flowerheads are 1-3" across, nodding (like the name says), made of 100-1000 tubular disk florets, each with its apical portion divided into 5 purplish-pink filaments and with a single, very long style. Beneath the large, showy flowerheads are stout, triangular, purplish phyllaries, each with a stout spine. When in bloom, the large size of the flowers and characteristic large phyllaries make it impossible to confuse with any of our other local thistles. Well loved by goldfinches, but considered a "noxious weed" by almost everyone else.

Carduus

Carduus nutans

nodding thistle [Blooms: Jun-Jul]

Northern catalpa's inflorescence is a pyramidal panicle with 10-30 flowers. Individual flowers are large (~2" across) and trumpet-shaped with two lobes, bright white with purple lines leading towards the corolla's center; two yellow-orange spots are present on the lower lateral edges of the corolla's opening. Two fertile and three sterile stamens, and a single, white style with a bifurcated stigma are present.

Catalpa

Catalpa speciosa

Northern catalpa [Blooms: Jun-Jul]

Spotted knapweed has pink to purplish flowers ~3/4" across composed of numerous tubular, branching, sterile ray florets with five lobes; the outermost ray florets are the longest. Disc florets ARE present, shorter and more erect than the ray florets but similar in appearance, with pink to white-tipped anthers and a divided style. The urn-shaped base of the flower is covered with tightly appressed oval bracts, each green with black tips; long, comb-like pale bristles radiate from the tip giving an appearance rather like a tick (inset).

Centaurea

Centaurea stoebe

spotted knapweed [Blooms: Jun-Sep]

White turtlehead flowers are ~1-1.5" long with a few basal green sepal-like bracts and a green calyx bearing five oval teeth with rounded tips. The cavernous tubular, creamy-white corolla has two large lips — the two-lobed upper lip functions as a hood, while the three-lobed lower lip, "bearded" with wooly hairs, functions as a landing area for pollinators. Inside the corolla is a slim white style that runs along the inside of the upper lobe but turns down sharply at the lip, and five hairy stamens (one of which is green and sterile).

Chelone

Chelone glabra

white turtlehead [Blooms: Sep-Oct]

"Canada thistle" is a calumny on poor Canada; this homely plant is native to Eurasia, not our northern neighbor. Flowerheads of Canada thistle are much smaller (1/2-3/4" across) than those of bull or field thistle and often occur in clusters on the plant. The involucre is goblet- rather than vase-shaped, covered by closely appressed green to purplish phyllaries, that have short, sharp, brown tips but no spines; there are only tubular disk florets with five thread-like, 1/4" long apical lobes, pink or pale lavender (rarely white) in color.

Cirsium

Cirsium arvense

Canada thistle [Blooms: May-Sep]

Field thistle is a native weedy plant often found in disturbed areas, up to 8' tall, but usually much shorter. Flowerheads occur on the tips of branches, are light pink, and about 2" across. The base (involucre) of the flowerhead is vase-shaped and covered with multiple series of closely appressed, overlapping phyllaries/bracts (often said to look like fish scales). Each bract has a a medial white line and a single, sharp, 1/4" long golden spine at the tip. Below the involucre are a few slender bracts that look like miniature versions of the stem leaves; these bracts curve upwards around the flowerhead.

Cirsium

Cirsium discolor

field thistle [Blooms: Aug-Sep]

The base (involucre) of the 1.5-2" wide flowerhead of bull thistle is vase-shaped and covered with numerous series of imbricated, spreading phyllaries/bracts that taper into stiff, sharp points. The upper portion of the flowerhead consists of numerous pinkish-purple to purple tubular disk florets that split apically into five thread-like lobes and a single protruding style. This is the only North American thistle with spines (albeit, short) on the upper surface of the leaves and one of the few with spreading, spiny bracts at the base of the flowerhead; native thistles lack spines on the stems.

Cirsium

Cirsium vulgare

bull thistle [Blooms: Jun-Aug]

Lily-of-the-valley's raceme bears 6-14 bell-shaped, 8 mm long (and wide), white flowers on one side of the stalk; it often nods at its tip. Individual flowers are bell-shaped with six recurved, pointed lobes around the mouth, white to light green, with six stamens and a single style with a three-lobed stigma hidden inside. The corolla is pendant, dangling from the raceme by 1/2" long, flexible pedicels that have light green, narrow bracts about as long as the flowers at their base.

Convallaria

Convallaria majalis

lily-of-the-valley [Blooms: Apr-May]

Mullein foxglove has an odd-looking but very attractive flower that always makes me think of Burt Lahr's Cowardly Lion in the (1939) Wizard of Oz. Individual flowers are about 1/2-3/4" long and across with a basal green calyx decorated with five blunt teeth. The bright yellow, tubular corolla terminates in five spreading lobes; the upper two lobes are reflected backwards, while the lower three lobes (presumably) function as a landing pad for pollinators (mostly bumblebees). From the front, the opening into the corolla is largely obscured by numerous fine yellow hairs that tend to hide the stamens (present in two distinct lengths) and the single style with a two-lobed stigma.

Dasistoma

Dasistoma macrophylla

mullein foxglove [Blooms: Jul-Aug]

Northern bush honeysuckle flowers occur in clusters of 2-7 arising from leaf axils or at the tips of year-old branches; the flowers are initially yellow but they turn orange-red with age. The flowers are funnel-shaped, 1/2-3/4" long, hairy on the inside, with four slender lobes and a fifth, wider and darker lobe; the base of the flower is surrounded by five triangular sepals as long as the floral tube. The five stamens are densely hairy with yellow anthers; the style is long, slender, green, with a dome-like stigma.

Diervilla

Diervilla lonicera

northern bush honeysuckle [Blooms: May-Jul]

Wild teasel produces one or more flowering stalks 2.5-6' tall, reddish- or pale green, with longitudinal ridges and scattered white prickles. The flowerhead is up to 4" tall and 1.5" across, initially egg-shaped but elongating as it matures. At the base of the flowerhead are narrow, prickly, sharply-pointed bracts up to 6" long that arch up to surround the flowerhead. Individual flowers are packed around the flowerhead like cells in a honeycomb, each flower with a 3/4" long bract that tapers to a sharp point. Individual flowers are white along most of their length, tubular, about 1/2" long, flaring out to four pale purple or lavender lobes; four stamens with white filaments and purple to lavender anthers and a single white style all protrude well beyond the end of the tube. Flowers bloom initially about halfway up the flowerhead but, later, rings of blooms develop at the base and apex of the flowerhead. Cut-leaved teasel was introduced to North America in the 18th century; the spiky flowerheads were used to comb wool and to raise the nap of (aka, "full") fabric. (Thus the species name, fullonum.) I've only seen this plant once in Jackson Park, but hope it returns (but not in excessive numbers).

Dipsacus

Dipsacus fullonum

wild teasel [Blooms: Jul-?]

Cut-leaved teasel behive-shaped flowerheads are 2-4" long and 1.5" across, spiky in every aspect. At the base of the flowerhead are 2-4" long, narrow bracts with sharp points that protrude radially. (These bracts in wild teasel, Dipsacus fullonum, arch up around the flowerhead.) Individual flowers are packed around the flowerhead like cells in a honeycomb, each flower with a 3/4" long bract that tapers to a sharp point. Individual flower are white, tubular, about 1/2" long, flaring out to four lobes; four stamens with white anthers protrude from the tube well beyond its end and there is a single style with a stigma positioned laterally at the style tip. Flowers bloom in a circle progressively from the base of the flowerhead to its tip.

Dipsacus

Dipsacus laciniatus

cut-leaved teasel [Blooms: Jul-Aug]

Broad-leaved helleborine's inflorescence is a 4-12" long raceme with 15-50 flowers, all on one side of the flower stalk. Individual flowers are 1/2-3/4" wide. The petals are greenish-purple with the lower petal forming a pale red bowl; behind the petals, the three sepals are pale green with purple stripes. (The sepals are as long as the petals, as are the bracts below the flowers' stalks.) The fruit is a hairy capsule ~1/2" long, and egg-shaped. Broad-leaved helleborine prefers woodlands.

Epipactis

Epipactis helleborine

broad-leaved helleborine [Blooms: Jul]

Spotted Joe-Pye weed flowerheads are pink to pinkish-purple, about 8 mm long, consisting of 8-20 disk florets, each with a tubular corolla with five tiny spreading lobes at its apex, five stamens with white anthers, and two long, thin white styles that extend well outside the floret; there are no ray florets. The flowers make either a rather flat or domed cluster (panicle) at the apex of the plant. The bracts (phyllaries) around the base of the flower are purple-tinged or the same color as the disc florets. Spotted Joe Pye weed (E. maculatum) has purple or purple-spotted, hairy stems and flowers with 8-20 disc florets; sweet Joe Pye weed (E. purpureum) has green, hairless stems with purple color only at the leaf nodes and flowers with 4-7 disc florets.

Eutrochium

Eutrochium maculatum

spotted Joe-Pye weed [Blooms: Jun-Sep]

Sweet Joe-Pye weed's inflorescence is a domed or pyramidal panicle. The flowerheads are whitish-pink to pinkish-purple and strikingly variable in color between plants, 1/4-3/8" long, consisting of 4-7 disk florets, each with a whitish-pink to purplish-pink tubular corolla with five lobes at its apex, two long, thin white styles extending well outside the floret and five stamens fused to the corolla about halfway up its length; there are no ray florets. The flowerheads make a domed (rather than flat) cluster at the apex of the plant. The bracts (phyllaries) around the base of the flowerhead are pale pink.

Eutrochium

Eutrochium purpureum

sweet Joe-Pye weed [Blooms: Jul-Aug]

Prairie smoke leaves, stems, and the exterior of the flowers are densely hairy. Reddish-green or -purple flowering stalks arise from the center of the leaf rosette; they produce three buds at their apex which develop into three nodding flowers (as implied by the species name) with a pair of bracts at the base of the triplet that are divided into narrow strips as if cut with scissors. Each flower is 3/4-1" in both dimensions; five triangular red to reddish-purple sepals hide almost all the remainder of the flower, covering all of the five white or reddish petals except their tips, a ring of stamens, and a central cluster of pistils. The opening to the interior of the flower is highly constricted. A spreading, narrow floral bract identical in color to the sepals lies between each pair of sepals (for a total of five). After fertilization (by bumblebees), the flower peduncle straightens so the flower points straight up. A dense cluster of seeds attached to 2" long, feathery plumes (the "smoke") transform the appearance of the flower; the seeds are later dispersed by the wind. Frustrated bumblebees unable to force their way into flowers (and some wasps and beetles) may occasionally chew their way through the sepals and petals near the base of the flower to access the nectar. No other avens (Geum sp.) in Illinois produces seeds with feathery plumes; prairie smoke's closest relatives in Jackson Park, whte avens and rough avens, look nothing like it.

Geum

Geum triflorum

prairie smoke [Blooms: Apr-Jun]

Ground ivy flowers are 1/2" long and arise from the leaf axils; they are purplish, trumpet shaped, with a notched upper and lower (the largest) lobe and two small side lobes; the "throat" of the lower lobe is hairy. There are four stamens (two long, two short) with purple to blue anthers, and a single pistil with a bifurcated purple style. The corolla of the flowers is cupped by a hairy, green, tubular calyx that has 15 ridges distributed around the calyx running longitudinally, and five triangular teeth at the apex of the calyx. The fruit is a nutlet that nestles in the calyx.

Glechoma

Glechoma hederacea

ground ivy [Blooms: Apr-May]