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Swamp dogwood's flat-topped panicles of flowers are 2-3.5" across. Single flowers are about 1/4" across with a light green, tubular calyx, four lance-shaped white petals, four stamens, and a single style.

Cornus

Cornus obliqua

swamp dogwood [Blooms: Apr-Jun]

Gray dogwood flowers occur in dome-shaped panicles with creamy-white branches 1.5-2.5" across and tall. Individual flowers are 1/4" across with a short calyx bearing four short teeth, four lance-shaped, creamy-white petals, four stamenns with pale yellow anthers, and a central, green-tipped style. The fruit is a small (1/4"), ball-shaped drupe, white when mature; when the fruit is mature, the branches of the panicle turn from white to bright red. Rough-leaved dogwood and red-osier dogwood also produce white fruit, but their panicles are flat-topped, not domed; the panicle branches are also not red in red-osier dogwood, but they are in rough-leaved dogwood so carefully inspect the stems (hairy) to see if the specimen in hand might be the latter.

Cornus

Cornus racemosa

gray dogwood [Blooms: May-Jun]

Red-osier dogwood flowers occur in flat-topped or slightly concave panicles 2-3" across; each flower is about 1/4" across with a small green calyx with four teeth; four white, lance-shaped petals; four stamens longer than the petals; and a single style rising from a reddish ovary. The fruit is a drupe about 1/4" across, white at maturity; the panicle branches remain green (unlike gray dogwood where the panicle branches turn red).

Cornus

Cornus sericea

red-osier dogwood [Blooms: Apr-Sep]

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]

Yerba de tajo's flowerheads arise in groups of 1-3 from the leaf axils on short pedicels; individual flowerheads are 1/4-1/3" across with 8-16 triangular, green, basal bracts, numerous (20+) off-white, thin ray florets with a protruding style, and numerous (15+) light grey to cream disc florets with four tiny spreading lobes, and four protruding light brown anthers and a branching style. Ray flowers are pistillate; disc flowers have both stamens and pistils.

Eclipta

Eclipta prostrata

yerba de tajo [Blooms: Aug-Sep]

Aunt Lucy (Ellisia nyctelea) flowers arise from the leaf axils. The flowers are small and tubular (1/4" wide x 1/2" long); the five petallike lobes are white with purple lines or specks; the five stamens are hidden within the corolla, alternating with the corollar lobes and the style is divided for about half ts length; the sepals are hairy and as large as the petals. The fruit is a 1/4" long hairy, white body that looks like two spheres squashed together, resting on the sepals; it usually contains 4 seeds. This species is very common in late spring in open but shaded areas on Wooded Island. How it acquired the moniker "Aunt Lucy" is obscure.

Ellisia

Ellisia nyctelea

Aunt Lucy [Blooms: Apr-Jun]

Cinnamon willowherb flowers are 1/4-1/3" across and arise from the axils of the upper leaves on 1/2" flower stalks, but the ovary of the flower is a hairy, elongate cylinder slightly wider than the flower stalk; the base of the sepals and petals (less than 1/4" long) may thus be elevated 1.5" above the leaf axil — a tiny flower on the tip of a long cylinder. Above the elongated ovary are four green sepals (with pink or purple tints), four deeply-notched white or light pink petals, a stout pistil with a knobby end, and eight stamens, four long, four short. After fertilization, the ovary elongates to as much as 3" long, dries to a brown color, then splits into two or four segments to release tiny seeds suspended under a tuft of long light brown hairs.

Epilobium

Epilobium coloratum

cinnamon willowherb [Blooms: Jul-Sep]

European spindletree flowers (usually less than 7) occur in clusters (cymes) with long peduncles; they have four sepals, four petals, four stamens with white anthers, and a single stout style. The greenish-white or yellow petals on the flowers appear to be very narrow, half the width of the petals of Hamilton's spindletree. (In reality, the petals are curled into a U-shape towards the stem so they only appear narrow.) The sepals are pale green, about half the length of the petals, and bent back beneath the flower. The fruit is pink, not red; the arils covering the seeds are orange, not red or scarlet. European spindletree blooms later in the spring in Jackson Park than Hamilton's spindletree.

Euonymus

Euonymus europaeus

European spindletree [Blooms: Apr-Jun]

Tall boneset flowerheads are tiny (1/8" across) with no ray florets and typically only five disc florets. Disc florets are dull white with a tubular corolla and a long bifurcated style that extends well away from the floret; the base of the style is greenish and surrounded by five brown stamens with white tips. The apex of the corolla has five prominant, triangular lobes that give the florets a star-like appearance.

Eupatorium

Eupatorium altissimum

tall boneset [Blooms: Aug-Oct]

Common boneset's upper stem and branches bear clusters 2-8" across of white flowerheads. Each flowerhead is about 4-6 mm across consisting of ~15-20 dull white disk florets (ray florets are absent); florets have a tubular corolla with five triangular lobes at the apical end and a long, bifurcated style surrounded at its base with a brown column of five stamens with purplish anthers. Ironically, "common" boneset is less common than late boneset or tall boneset in Jackson Park.

Eupatorium

Eupatorium perfoliatum

common boneset [Blooms: Jul-Aug]

Late boneset's inflorescence is a flat-topped or shallowly-domed panicle with numerous flowerheads. Individual flowerheads are composed of 12-15 greyish-white disk floret (ray florets are absent) about 1/4" long with a tubular corolla with five small, triangular apical lobes and a long white bifurcated style extending well out from the floret surrounded by five black stamens. Leaf venation, lack of leaf hairs, and and smaller flowerheads (~5-8 florets) distinguish tall bonset (E.altissium) from late boneset (E. serotinum; 12-15 florets).

Eupatorium

Eupatorium serotinum

late boneset [Blooms: Aug-Oct]

Gallant-soldier (aka, small-flowered galinsoga) flowerheads are about 1/4" across; they have 4-8 (usually 5) ray florets with a single minute (about 2x2 mm) white petal notched to produce two or three lobes; the ray florets are distributed around the circumstance of the disc. There are 15-50 golden yellow, tubular disc florets with five short triangular lobes at their apex. Both ray and disc florets are fertile; the ray florets are pistillate while the disc florets are perfect (both pistils and stamens). The fruit (a cypsela) consists of a black, conical seed suspended beneath about five off-white, papery, fringed scales that act as a parachute. Gallant-soldier is very similar to galinsoga (Galinsoga quadriradiata); the latter has larger flowerheads and ray floret petals.

Galinsoga

Galinsoga parviflora

gallant-soldier [Blooms: Aug-Sep]

Galinsoga (aka, Peruvian daisy or shaggy soldier) flowerheads are small (1/4" across) with 4-8 (usually five) widely separated 2.5 mm long, white ray florets with three teeth at their tips. The 15-35 disc florets are yellow. Both ray and disc florets are fertile; the ray florets are pistillate while the disc florets are perfect (both pistils and stamens). The fruit (a cypsela) consists of a black, conical seed suspended beneath about five off-white, papery, fringed scales that act as a parachute. A poisonous plant (Tridax procumbens) with nearly identical flowers (but distinctly different leaves) is (luckily) restricted to FL and TX in the U.S. so not likely to show up in Jackson Park. The name Galinsoga ciliata, sometimes still used for Galinsoga quadriradiata, is invalid (ITIS); according to the USDA Plants database, C. ciliata has been superceded by either G. quadriradiata or G. urticifolia.

Galinsoga

Galinsoga quadriradiata

galinsoga [Blooms: Jun-Oct]

Cream gentian the leaves are olive-green, lance-shaped with a pronounced fold along the midvein, 3" long and 2" across, and clasp the stem. Although most leaves are opposite (in pairs), the leaves just below the flowers occur in a whorl of three. The flowers are mostly apical, some version of white or cream, tubular, with the petal's veins outlined in green, about 1-2" tall and 3/4" across, and oriented near-vertically. The five petals remain tightly appressed, with only a small opening where their apices meet; the five stamens and pistil with a bifurcated stigma are usually hidden from view. Bumblebees are the primary pollinators.

Gentiana

Gentiana alba

cream gentian [Blooms: Jul-Oct]

Carolina crane's-bill flowers are small (about 1/4-3/8" across), in small clusters on stubby pedicels. Each flower contains five dull-green, very hairy, lance-shaped sepals with long, scarlet-tipped awns on the tips, five white to pinkish-lavendar petals shorter than the sepals, ten stamens with tan anthers, and five stamens fused at their bases. The fruit is spherical with a very long beak divided longitudinally into five sections; when ripe (the fruit turns bright red) , the beak splits violently into five strips attached to each other at their distal ends, flinging the seeds far from the parent plant. Carolina crane's-bill has white to pinkish flowers with sepals longer than the petals; cut-leaved crane's-bill (Geranium dissectum) has deep pink to purple flowers with sepals the same length as the petals.

Geranium

Geranium carolinianum

Carolina crane's-bill [Blooms: May-Jun]

Wild hydrangea canes produce a flat terminal panicle 3-6" across with 100-500 flowers of two kinds — small, fertile flowers filling most of the area and a few, sterile pseudo-flowers around the margin that are 3-4 times larger than the flowers in the center and seem to function only as an advertisement for pollinators. The central, fertile flowers are about 1/4" across with a green calyx made of five separate sepals; five greenish-white or cream petals about 1/8" long; 8-10 stamens with long filaments and oblong, white anthers; and a pistil bearing two styles with knob- or club-like stigmas. The sterile, outer pseudo-flowers have 3-4 fused petal-like, white bracts (or sepals; sources differ) with a central structures that visually is reminiscent of stamens or styles; the pseudo-flowers persist long after the inner flowers have been fertilized and have produced a two compartment seed pod that is ribbed and bears a pair of tiny horns (the styles) on its upper end. Wild hydrangea is relatively rare in northern Illinois; in Jackson Park it prefers wooded area by walking paths.

Hydrangea

Hydrangea arborescens

wild hydrangea [Blooms: Jun-Aug]

American water-willow produces long (up to 6") peduncles from some of the upper leaf axils that have clusters of flowers on their tips. Individual flowers are 3/4" across with a short, tubular, 1/4" long, green calyx with five teeth and a tubular corolla with four lobes — an upper lobe with a shallow V-notch, two widely spreading lateral lobes, and one lower lobe at right angles to the other three. Both the lateral and lower lobes are folded downward along their midlines, producing a U-shaped cross-section. All of the lobes are white or pale purple with a darker splotch on the end of the upper lobe and dark purple spots along the midline of the lower lobe and at the base of the lateral lobes. There are two stamens, each with a dark brown pair of anthers posed in front of the upper corolla lobe and a single, narrow, white style running along the midline off the upper lobe and protruding beyond its upper boundary.

Justicia

Justicia americana

American water-willow [Blooms: Jun-Aug]

Wood nettle plants may be either monoecious (separate male and female flowers on the same plants) or unisexual (only male or only female flowers). Male flowers are produced from branching cymes 4" long that arise from the leaf axils; female flower are produced from branching cymes, also 4" long, localized near the apex of the stem. Male flowers are small (1/8" across), consisting of five narrow, greenish-white sepals and five stamens; there are no petals but there is a vestigial pistil. Female flowers are about the same size (1/8" across) with four green sepals (two larger, two smaller) that look like tiny leaves with undulating edges and an ovary with a long, white, vertically-oriented J-shaped style that tapers to a point. The female flowers are wind-pollinated. The fruit is circular in outline but very flattened, green turning black with maturation, on a short winged stalk; the remains of the style are attached at the free end of the fruit.

Laportea

Laportea canadensis

wood nettle [Blooms: Aug-Sep]