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Pointed-leaf tick-trefoil flowers are a little over 1/4" long, pea-like, with four (or five) rose-pink petals — a banner (parallel to the other petals), two lateral wings, and a tube-like keel formed from either a single petal folded lengthwise or two fused petals (opinions differ). Emerging from between the wings and keel is a stout, upward-curved, white tube that bears a single style and several stamens at its tip.

Desmodium

Desmodium glutinosum

pointed-leaf tick-trefoil [Blooms: Jun-Sep]

Prairie cinquefoil (aka, tall cinquefoil) flowers are about 3/4" across and have white to cream-colored petals, narrowest at the base; the sepals are light green and as long or longer than petals, tapering to a sharp tip; about 20 bright golden-yellow stamens and anthers; and the pistils in the center of the flower also bright golden-yellow. Prairie cinquefoil and sulfur cinquefoil are easy to confuse, but flowers of prairie cinquefoil are cream colored, not yellow and the leaves are pinnately compound, not and palmate.

Drymocallis

Drymocallis arguta

prairie cinquefoil [Blooms: Jun-Jul]

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]

Rattlesnake master inflorescences consist of whitish-green spiky balls 1/2-1" across made up of small florets enclosed by prickly bracts; the florets have five short, rounded petals, five stamens, and a long, divided white pistil that protrudes well beyond the edge of the floret. Note that, if you're bitten by a rattlesnake, this plant will be of no use to you whatsoever.

Eryngium

Eryngium yuccifolium

rattlesnake master [Jun-Sep]

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]

Flowering spurge "flowers" are deployed in an open, flat-topped inflorescence (panicle); individual "flowers" are 1/4-3/8" across, a cup-like, five-lobed cyathium (unique to euphorbs) containing the five white "petals" (actually white bracts), a green ring of nectar glands around the base of the "petals," and the stamens or styles. Male flowering spurge cyathia have three stamens, each with a white filament and a yellow anther; female flowering spurge cyathia have both an ovary with a tripartite style with six stigmas, and three (sterile?) stamens. (If you're confused about the architecture of cyathia, see seaside sandmat (Euphorbia polygonifolia) for a clearer example.) After fertilization, the fruit develops as a unmistakable three-celled, bulbous green capsule on a short stalk in the middle of the original flower with the remnants of the style at its tip.

Euphorbia

Euphorbia corollata

flowering spurge [Blooms: Jun-Oct]

Black bindweed flowers develop in singletons or pairs from the leaf axils or directly from the stem. Flowers are 1/8-1/4" long; they have 3-5 greenish-white, white, or light purple petal-like tepals, the outer three tepals with a ridge or keel down the midline on the outer surface. Six to eight stamens with purple anthers surround fused green styles with a dome-shaped stigma in the middle of the flower; the flower usually opens only partially (like a tulip). The fruit is three-sided, with a tubercle-covered surface, about 1/4" long, black when fully mature. Black bindweed is very similar to climbing false buckwheat (Fallopia scandens).

Fallopia

Fallopia convolvulus

black bindweed [Blooms: Jun-Jul]

Climbing false-buckwheat stems are round, angular, or ridged in section, often with hairs on the ridges. Racemes of flowers arise from the leaf axils; the flower stalks are usually vertical, 3-8" long and bear both erect flowers and drooping fruits. Individual flowers are greenish-white, about 3/16" across have eight stamens with white anthers and an ovary bearing a tripartite style; the thee outermost tepals (petals) have obvious wings, unsually with an undulating margin; the inner two tepals are simple ovals. The fruit (~3/8" long) has a greenish center with three white wings; the 3 outer tepals with enlarged wings enclose the seed. (The fruit resembles a much-enlarged version of the fruit of curly dock (Rumex crispus).) Climbing false-buckwheat is very similar to black bindweed (Fallopia convolvulus) but is far more common in Jackson Park.

Fallopia

Fallopia scandens

climbing false-buckwheat [Blooms: Aug-Sep]

Queen-of-the-prairie produces over 100 flowers (1/3" wide) in the panicle with five triangular, purplish sepals, five rounded pink petals with narrow bases, 15+ long white stamens with pink anthers, and a ring of 5-15 curved styles with large, disk-like, white stigma. The fruits are striaght or slightly curved stout banana-like spindles 1/4-1/2" in diamater on a narrow stalk.The numerous pink flowers with their long protruding stamens tipped with pink anthers gives the inflorescence the air of pink clouds, or possibly cotton candy. Rare, but unmistakeable if you spot it. Critically imperiled in Illinois (and elsewhere in the Midwest).

Filipendula

Filipendula rubra

queen-of-the-prairie [Blooms: Jul-Aug]

Dyer's greenweed is a woody shrub that grows 2-3' tall, introduced from Europe and Siberia (and probably escaped from gardens). The multiple stems are green and round in section. The leaves are 1/2-1" long and about half as wide, alternate, sessile, lance-shaped or oblong, hairy on the upper surface, with smooth margins. The inflorescence is a 1-3" wide raceme. Individual flowers are 1/2-3/4" across, bright yellow, with a strong resemblance to tick-trefoils — a banner held at about a 45° angle, two wings and two parallel keels. The fruit is a 1-3" long pea-like pod containing 8-12 black, shiny seeds. The common name derives from the use of this plant to produce a yellow dye.

Genista

Genista tinctoria

dyer's greenweed [Blooms: Oct]

Cut-leaved crane's-bill's very attractive flowers occur in pairs. The base of the flower is covered by five green sepals the same length as the petals, covered externally in glandular hairs; the tips of the sepals are drawn out into a short (1-2 mm) awn that is scarlet-tipped. The five petals are a deep pink to purple in color; there are five pink stamens with purplish-yellow anthers; the five styles produce a deep pink, star-shaped stigma at their tips. The fruit consists of five hairy spheres around the base of an elongate "crane's bill" which splits explosively when ripe into five strips attached at their distal ends, flinging the seeds far and wide. Carolina crane's-bill (Geranium carolinianum) has white to pinkish flowers with sepals longer than the petals; cut-leaved crane's-bill has deep pink to purple flowers with sepals the same length as the petals.

Geranium

Geranium dissectum

cut-leaved crane's-bill [Blooms: May-Jun]

White avens blooms slightly later than rough avens (Geum laciniatum); it reaches about the same size (1.5-2.5' tall). The flowers are 1/2" diameter; they have five green sepals that are white-edged, pointed, and the same length or (usually) shorter than the petals; five white, rounded petals with a narrow attachment; and numerous (25-120) stamens surrounding a dome-shaped mass of green styles about a third the diameter of flower. The sepals initially lie under the petals but later become reflexed back parallel to the flower peduncle.The spherical fruit is covered with long, hooked spines (actually, persistant styles) that help the seeds stick to fur and clothing. White avens is distinguished from rough avens (G. lacinatum) by their flower stalks covered with short, fine hairs (rather than long, coarse hairs) and sepals that are shorter than the petals.

Geum

Geum canadense

white avens [Blooms: Jun-Jul]

Rough avens flowers are 1/2" wide, with five triangular green sepals longer than the petals, five cream or white, circular petals with narrow attachments, and numerous (25-120) stamens with (initially) cream-colored anthers distributed around a central gumdrop-shaped mound of green carpels with long styles. The fruit is more or less spheroid, 3/4" across, and covered with long, hooked spines (actually, persistant styles) that help the seeds attach to clothing and animal fur. Note that some sources identify this species as Geum virginianum, but G. virginianum is the cream avens according to the USDA Plants database; Hilty (ILW) lists G. virginianum as "restricted to southern Illinois". The two species are very similar, but G. lacinatum has very hairy stems and hairless receptacles and G. virginianum has smaller flowers (1/3") with cream-colored petals dwarfed by the sepals. Rough avens is distinguished from white avens (G. canadense, also found in Jackson Park) by petals that are shorter than the sepals and their very hairy flower stalks; rough avens also blooms earlier than whte avens.

Geum

Geum laciniatum

rough avens [Blooms: June]

Honey locust is a native tree that grows 50-100' tall; it has a single trunk 2-3.5' in diamater. The bark on the trunk is gray-black, divided into plates with peeling edges; the bark of twigs and branches is smoother, brown, and hairless. New shoots are green and fuzzy. Leaves are alternate and invariably compound, either even-pinnate (i.e., the leaflets are all paired, with no terminal leaflet) all 6-14" long with 5-11 pairs of leaflets, or bipinnate (i.e., the primary divisions of the compound leaf are themselves pinnate) with 4-7 pairs of even-pinnate leaflets 6-14" long, each with 5-11 pairs of leaflets. Leaflets are 3/4-1.5" long and about a third as wide. Thorns, both simple and branched, are usually present, especially on the trunk, but a thornless form exists; newly formed thorns can be a brilliant red. Flowers are present in 2-5" long racemes, usually as either male or female, but perfect flowers may be present. The flowers are small (1/8-1/4" across) and greenish-yellow. The fruit is a 6-14" long, dark-brown seedpod.

Gleditsia

Gleditsia triacanthos

honey locust [Blooms: May-Jun]

Kentucky coffeetree produces a single 1.5-3' diameter trunk that, with its branches, can reach heights of 60-90'. The trunk bark is rough, scaly, gray or gray-brown; the bark on the branches is smoother, gray; the bark on the twigs is gray or brown with whitish lenticels. The leaves are alternate, bipinnate-compound, with 5-9 pairs of pinnate leaflets, each with 6-14 pairs of subleaflets. The entire compound leaf can be 3' long and 2' across, the largest leaf of any native tree in Illinois. Individual trees may produce only male flowers, only female flowers, or "perfect" flowers with both male and female organs flowers; the flowers develop as racemes on terminal branches fairly high in the crown shortly after the tree leafs out in the spring. Flowers are about 3/4" long and 1/2-5/8" across with a narrow, tubular calyx bearing five thick, narrow, sepals, and five narrow, greenish-white petals, slightly wider than the sepals, and a central column about as long as the petals that contains the reproductive organs. The male and perfect flowers have 10 fertile stamens (in alternating long/short pairs) in the central column; the female and perfect flowers have a fertile ovary and a single style contained in the central column. The calyx, sepals, and petals are all densely wooly with short hairs. The fruit is a stubby, reddish-brown seedpod 3-6" long and 1.5-2" across, somewhat flattened but less so than the fruits of honey or black locust. The seeds are brown, VERY hard, oval, and about a half inch long and across; they are toxic when raw but can be eaten after roasting.

Gymnocladus

Gymnocladus dioicus

Kentucky coffeetree [Blooms: May-Jun]

Although stickseed flowers are tiny (1/8"), they have the ususal complement of parts — a hairy green calyx with five long, narrow teeth that alternate with the petals; five rounded white (or light blue) petals (actually lobes of the corolla tube); five arching, scale-like structures surrounding the opening to the tube; five stamens largely hidden inside the corolla tube; and a four-lobed ovary with a short style, similarly hidden inside the corolla tube. The fruits are globular, <1/4" across, densely covered with hooked prickles; they are purportedly the most difficult of such "sticktights" to remove from clothing.

Hackelia

Hackelia virginiana

stickseed [Blooms: Jul-Aug]

Cow parsnip flowers are present in 6-8" wide, flat umbels (like Queen Anne's lace) that arise from the central stem or from leaf axils. Beneath each flower cluster are four or more needle-like, fuzzy green bracts; the bracts fall off after the fruit begins to form. Individual flowers are 1/4" across with five white petals that are notched at their tips; in flowers on the edge of an umbel, one petal is visibly larger than the other four. A somewhat lumpy, cream-colored, hairy ovary occupies the center of the flower from which arise two short styles; five stamens with pale yellow anthers arc laterally from under the ovary. Each fruit is heart-shaped, flattened, and contains two seeds.

Heracleum

Heracleum sphondylium

cow parsnip [Blooms: May/Jun-?]

Halberd-leaved rose-mallow is a striking wild hibiscus, usually found near water, whose stems can get 6' tall. Flowers arise from leaf axils, are trumpet-shaped, up to 5" across, with five rounded, partially overlapping white to pink petals; a central columnar reproductive structure covered in creamy-white stamens (with reddish-tan anthers) in whorls, and a terminal divided style with five recurved tips, each bearing a stigma shaped like the head of a pin. Behind the corolla is a green calyx with five lobes, and ~12 rod-like, curved, green bractlets below the calyx that taper to sharp points. The throat of the flower is a deep reddish-purple or rose pink. Seed pods form within the persistant sepals; the seed pod is divided into five sections filled with fuzzy brown seeds. The three-lobed (halberd-shaped) or five-lobed (maple leaf shaped) leaves distinguish this species from other rose-mallows. (Only swamp rose-mallow, Hibiscus moscheutos, also occurs in Jackson Park.)

Hibiscus

Hibiscus laevis

halberd-leaved rose-mallow [Blooms: Jul-Aug]