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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]

Lance-leafed goldenrod is only distantly related to the other goldenrods (all genus Solidago) found in Jackson Park. The inflorescence is a flat-topped or slightly domed panicle. Flowerheads are cylindrical, minute (1/8" across, the smallest of the goldenrods), with 15-25 ray florets with minute petals and 5-10 disc florets. The outermost bracts around the base of the flower are green-tipped. Flowers across the inflorescence bloom at different times so the inflorescence often looks a bit shopworn. Lance-leafed goldenrod refers wet, soggy habitats.

Euthamia

Euthamia graminifolia

lance-leafed goldenrod [Blooms: Jul-Sep]

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]

Indian blanket flowers are 1-2.5" across with 6-15 sterile ray florets; the petals are 3/4-1.25" long, red or brownish-red with yellow tips; the base of the petal is narrow and the tips of the petals are divided into three sharp or rounded teeth or lobes. Disc florets are brown, numerous (40-100+), with tubular corollas that may be orangish, red, brownish-red, or purple with five tringular, hairy lobes at the apex; the flowers are perfect with both stamens and styles.

Gaillardia

Gaillardia pulchella

Indian blanket [Blooms: Jul-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]

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]

Sneezeweed flowers (1-2" across) have a more or less hemispherical central disc of 200-400 yellow-orange disc florets (which have both pistils and stamens) are each less than 1/8" across, surrounded by 10-15 pistillate ray florets that are triangular (narrowest at the insertion on the central disc) and three- or four-lobed along the squared-off distal margin ("doubly-notched"). The domed central disc on the flowers and the winged stems are diagnostic for this species. The base of sneezeweeds' flowers are covered by a single layer of long, narrow bracts that are fused together at their bases. Sneezeweed flowers are very similar to bitterweed (Helenium amarum) but the latter has long, thread-like leaves; I've not seen bitterweed in Jackson Park. The foliage contains sesquiterpene lactones that are bitter and toxic to mammalian herbivores, including cattle and sheep. The name "sneezeweed" may actually come from observation of Native American's use of snuff made from this plant.

Helenium

Helenium autumnale

sneezeweed [Blooms: Aug-Oct]

Sawtooth sunflower flowerheads are 2.5-4" across with 10-20 bright yellow ray florets and over 100 tubular golden-yellow disc florets with five protruding brown anthers fused around a yellow style with a bifurcated stigma. Behind the flowers are multiple layers of spreading bracts that are pointed with hairy margins, especially near their base. Only the disc florets are fertile; the ray florets are sterile. (This is true throughout the genus Helianthus, although this situation seems more understandable (to me) than the the situation in the genus Silphium, where the opposite is true.) Sawtooth sunflowers can be distinguished from other Helianthus spp. by their hairless, reddish-purple stems; the arching leaves with a longitudinal fold are also characteristic but not definitive.

Helianthus

Helianthus grosseserratus

sawtooth sunflower [Blooms: Jul-Sep]

Jerusalem artichoke should rightly be called a "sunflower" like the other four members of the genus Helianthus present in Jackson Park. Five to fifteen flowerheads ride on hairy peduncles up to 8" long and are 2.5-3.5" across; each is cupped by 2-3 overlapping series of phyllaries (bracts) that are more triangular than lance-shaped, hairy, and sharply pointed. The flowerheads consist of 10-20 sterile, yellow ray florets; the 60+ fertile disc florets consist of tubular yellow corollas about 1/4" long with five lobes at their apex and five protruding brown or black anthers fused around a yellow style with a bifurcated stigma. Jerusalem artichoke was cultivated by the indigenous peoples of the midwest for its tasty and carbohydrate-rich tubers.

Helianthus

Helianthus tuberosus

Jerusalem artichoke [Blooms: Aug – Oct]

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-?]

Dame's rocket flowers occur in clusters (racemes) of up to 30. Each flower is 3/4-1" across and long, with a long, narrow, tubular, pinkish-green calyx composed of four long narrow sepals. The calyx opens through a narrow throat into four rounded, pinkish-purple (sometimes white) petals; the six pale yellow stamens and the multiple styles poke to various degrees out of the throat. Stems, leaves, pedicles, and the flower calyxes are all downy or hairy. The fruits are long (up to 4"), narrow, ascending, downy cylinders (siliques, typical of mustards) filled with flattened, oblong seeds. The flowers are very phlox-like, but phlox flowers have five petals, and dame's rocket only has four; phlox leaves are opposite on the stem (not alternate) and are narrower.

Hesperis

Hesperis matronalis

dame's rocket [Blooms: Apr-May]

Flower-of-an-hour flowers are borne singly on hairy flower stalks that arise from the leaf axils; the flowers are 2" across, with five partially-overlapping petals that are white or pale yellow with deep purple bases. Sepals are pale green, translucent, and membranous with deep purple, hairy veins. The numerous stamens are borne on a "staminal column" that surrounds the base of the style; the filaments are maroon and the anthers are golden yellow. The single style is white where it rises above the staminal column and is divided at the tip into five knobby stigmas.

Hibiscus

Hibiscus trionum

flower-of-an-hour [Blooms: Jul-Sep]