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Prairie ragworts stems and leaves are covered with cobwebby hairs and the leaf blade with felt-like hairs. Cobwebby hairs also cover the flower stems which bear a cluster of 3-12 flowerheads at their apex. Individual flowerheads are 1/2-3/4" across, with 7-12 yellow ray florets and 60-70+ orangish-yellow disk florets; both ray and disk florets have a single style and five stamens. The central disk is about 8 mm across. The fruit is a single seed suspended from a tuft of white hairs (like a dandelion). The underside of the flowerhead is covered by a single series of light green bracts (phyllaries) also covered with cobwebby hairs. Prairie ragwort can be usually distinguished from other Packera spp. by the extensive cobwebby hairs on the stems and leaves. Butterweed (Packera glabella), balsam ragwort (Packera paupercula), and prairie ragwort (Packera plattensis) are easy to confuse — all bloom in the late spring/early summer and all are weedy-looking plants with yellow/golden-yellow, daisy-like flowers. The flowers don't help to distinguish them; you'll need to look carefully at the leaf shape and presence/absence and quantity of wooly fine white hairs on the leaves and stems. Butterweed has large (10" long) basal leaves; the leaves are pinnatifid with multiple semicircular lobes and a circular terminal lobe. Balsam ragwort (Packera paupercula) basal leaves are no longer than 3", the flowerheads have 0, 8, or 13 ray florets, the phyllaries behind the flowerhead are purple-tipped, and wooly hairs are usually found in the leaf axils. Prairie ragwort (Packera plattensis) is extensively covered with white wooly hairs on the stems, leaves, leaf axils, and on the phyllaries behind the flowerheads.

Packera

Packera plattensis

prairie ragwort [Blooms: Apr-Jun]

Boston ivy is an exotic introduced from Asia; it is a woody vine up to 50' long (with occasional branches) that grows on or over fences, walls, concrete, masonry, and trees. The lower stems are woody and produce small brown rootlets to adhere to surfaces; upper stems are (also) hairless, green to orange-red in color, with branched tendrils that have adhesive pads at their tips. Leaves are alternate, 6" long and across exclusive of the long, slender petioles, palmately tri-lobed with undulating or crenate margins. Cymes of flowers lacking a distinct central axis arise from the leaf axils; the cymes are 4" in both dimensions. Individual flowers are 1/4" across; they have five yellowish-green petals, five stamens with yellow anthers, and a single style. Fertilized flowers produce berries 3/8" across. When mature the berries are dark blue with a whitish bloom, usually hidden beneath the leaves; the flower stalks are yellow- or brownish-green or a dull orange-red.

Parthenocissus

Parthenocissus tricuspidata

Boston ivy [Blooms: ??]

Woodbine is a woody vine that usually uses trees as a substrate; the vine can be as much as 60' long. The stem is initially green and hairless; as it matures it becomes woody and develops a reddish- or grey-brown color. The leaves are alternate, palmately compound, usually with five (rarely 4 or 7) leaflets that are about 5" long and 2.5" wide with coarse marginal teeth, shiny-green when young but getting duller with age; the compound leaf has a slender 6-8" long petiole. Three- to six-inch-long clusters of 10-75 flowers arise from the main vines opposite the leaves; the clusters have two main branches and multiply-branched flower stalks with no clear central stem. Individual flowers are inconspicuous, 1/4" across with five yellowish green petals with narrow margins perpendicular to the plane of the petal and a pointed, curled tip; the petals are initially spreading but later become reflected backwards. In the center of the flower are five pale red stamens with creamy white or purple anthers, a reddish ovary, and a single white, stubby, conical style. The fruits are round blue-black berries 3/8" across that are reminiscent of grapes in a cluster with red, branched flower stalks; each berry contains four seeds. Woodbine has palmate leaves with five leaflets, very similar to Virginia creeper (Parthenocissus quinquefolia), but lacks the distinctive aerial roots "bearded" with short tendrils that are present in Virginia creeper. Opposite the base of the leaf petiole on the stem, woodbine produces a thin filament that branches 2-3 times, anchoring the vine by twining around objects. In Virginia creeper, the equivalent filaments are stouter, branch up to 10 times, and end in robust, egg-shaped pads that attach to the substrate. The inflorescence of woodbine lacks a central axis; the inflorescence of Virginia has a distinct central axis. Wikipedia (https://en.wikipedia.org/wiki/Parthenocissus_inserta) lists other differences between the two species. Illinois Wildflowers, USDA Plants, and and World Flora Online consider the two species to be one; Minnesota Wildflowers considers them to be separate and distinct. Flora of North America indicates the correct scientific name for woodbine is Parthenocissus vitacea (not P. inserta), as does ITIS and MissouriPlants.com, implying that woodbine and Virginia creeper are distinct species. Both woodbine and Virginia creeper have 40 chromosomes. Lu et al.'s (2012, 2023) molecular and morphological analyses indicate that woodbine and Virginia creeper are very closely related but are distinct species, and I'll consider that to be correct here.

Parthenocissus

Parthenocissus vitacea

woodbine [Blooms: ??]

Wild parsnip is an exotic plant, native to Eurasia, in the carrot family (Apiaceae); it produces flat umbels of flowers (like Queen Anne's lace, except yellow). This is the wild version of the domestic parsnip. The compound umbels are 3-8' across, flat topped, with 15-25 umbellets; each umbellet includes 15-35 1/8" yellow flowers borne on 3/8" long pedicels. Individual flowers have five very short, yellow petals, initially curled inward, but later the petals reverse curvature and curl outwards; there are also five yellow stamens and two styles that arise from an ovary with a swollen, greenish-yellow nectar pad. The fruits are 1/4" long flat, oval, coin-like discs; when mature the disk is brown and the edges of the disk are winged.

Pastinaca

Pastinaca sativa

wild parsnip [Blooms: May-Jun]

Wood betony's numerous yellow (less commonly, reddish brown) flowers arise from a spike (raceme) at the apex of the stem; the blooms open in a wave from the base of the spike to its tip. The flowers tend to be twisted clockwise around their long axis by about 30° so that, viewed from above, the flower spike looks like a pinwheel. Individual flowers are 1/2-1" long, tubular, with a hood-like upper lip that curves down into two small "teeth" or "fangs" at its tip (a distinguishing character of this species) and a paler or white three-lobed lower lip that functions as a landing pad for pollinators. The four stamens are hidden under the upper lip of the corolla; they are of two lengths with light yellow anthers. The single style is also largely hidden under the upper corolla lip, although the tip of the style may protrude; the stigma looks like the head of a common pin. The fruit is a 1/2" long, angular capsule reminiscent of a shoe tree (as in footwear, not plants) that is initially green, turning brown as it matures.

Pedicularis

Pedicularis canadensis

wood betony [Blooms: Apr-Jun]

Clammy groundcherry flowers arise at the junction of two branches or at a leaf axil on 1/4", arching pedicels that permit the flower to droop. The flowers are up to 3/4" across, consisting of a green calyx half the length of the flower with five triangular teeth, a funnel-shaped, pale-yellow corolla with five shallow lobes, five stamens with large, creamy-yellow anthers, and a single central pistil. In the interior of the corolla surrounding the ovary are five brown smudges, one on each corolla lobe, that merge centrally into a purple-brown ring covering the ovary. Both the pedicel and the calyx are also covered with fine white hairs. After fertilization, the flowers are replaced by green (later brown) hollow husks (a persistant calyx), heart-shaped in longitudinal section, covering a 1/2" diameter spherical, green fruit that becomes yellow when ripe. All parts of clammy ground cherry contain a glycoalkaloid poison called solanine that causes a series of unpleasant and sometimes potentially fatal symptoms; clammy groundcherry is avoided by mammalian herbivores. Only the RIPE fruit is edible.

Physalis

Physalis heterophylla

clammy groundcherry [Blooms: Jul-Aug]

Smooth groundcherry flowers are yellow, bell-shaped, with five purplish-brown patches near the center, five stamens with yellow or purple anthers, and a single pistil; the flowers are suspended from a purplish-green pedicel 3/4-1" long. After fertilization, the flowers are replaced by a tomatillo-like fruit (often with ten purple meridional lines) that is a green (later brown) hollow husk (a persistant calyx) that is heart-shaped in longitudinal section, covering a 1/2" diameter spherical, green miniature tomato that becomes yellow when ripe. All parts of smooth groundcherry contain a glycoalkaloid poison called solanine that causes a series of unpleasant and sometimes potentially fatal symptoms; smooth groundcherry is avoided by mammalian herbivores. Only the RIPE fruit is edible (said to taste like an underripe strawberry).

Physalis

Physalis longifolia

smooth groundcherry [Blooms: Jun-Aug]

Common purslane has no inflorescence per se; flowers occur alone or in small terminal clusters. Individual flowers are 1/8-1/4" across with two or four green sepals, 4-6 yellow petals with notched tips, 6-12 stamens with yellow anthers, and a five-lobed style with 3-6 stigmas. Fertilized flowers are replaced by an oval or urn-shaped capsule about 8 mm long that splits open along a meridional seam to release the tiny, dark brown or black seeds.

Portulaca

Portulaca oleracea

common purslane [Blooms: Jun-Sep]

Silverweed is a low, sprawling native plant that occurs everywhere in North America from the southwest through northern Canada. The prominent red stolons give rise to both new rooted nodes where the stolons encounter wet soil and may also give rise to new leaves. There is a basal rosette of large (12" long x 4" wide) odd-pinnate leaves with 5-11 opposite leaflet pairs and a single terminal leaflet. Flower pedicels 2-6" long arise from stolon nodes. The flowers are bright yellow, solitary, and 3/4" across. Each flower has five light green, hairy sepals; 5-15 oval, yellow petals; a ring of ~20 yellow stamens with large flat anthers; and a central disc of 20 to over 100 yellow pistils. The sepals are shorter than the petals. Silverweed prefers sandy habitats like beaches.

Potentilla

Potentilla anserina

silverweed [Blooms: Jun-Aug]

Rough cinquefoil is considered to be native to both North America and Eurasia. Flowers may develop from the axils of the upper leaves but more usually occur (as a panicle of cymes) in a terminal inflorescence on flower stalks 1-2' tall. The flowers are small (1/3-1/2") and pale yellow; the petals are distinctly heart-shaped with narrow bases and the sepals are triangular and slightly longer than petals. About 15-20 yellow stamens surround a dome-shaped, yellow receptacle covered with styles. Beneath the sepals are five green oval bracts about the same length as the sepals when the flower is in bloom. Fruits develop as dry seeds (achenes) in the persistent flower calyx. Note that rough cinquefoil’s leaves have three leaflets, common cinquefoil's leaves have five, and prairie cinquefoil's leaves have 7-11.

Potentilla

Potentilla norvegica

rough cinquefoil [Blooms: Jun-Sep]

Sulfur cinquefoil flowers are 3/4" across, pale yellow with a golden center. Beneath the flowers are green bracts about the same length as the sepals but narrower. The sepals are equilateral triangles that are shorter than the petals while the petals are heart-shaped with the narrow point at the base of the petal (where the yellow color is often more intense). There are 25-30 stamens surrounding the central receptacle; the anthers have one or more central dark spots contrasting strongly with the generally yellow anther (but these spots may be difficult to see). Sulfur cinquefoil is similar to prairie cinquefoil, but sulfur cinquefoil's flowers are yellow, not cream colored and its leaves are palmately compound, not pinnate. After fertilization, the sepals close over the ovary forming a capsule around the maturing seeds. The seeds are dry achenes less than 2 mm long with a coarsely wrinkled, brown surface. Sulfur cinquefoil was accidentally introduced to North America from Europe; the first recorded observation was in Montreal in 1852. By 1879, sulfur cinquefoil had become naturalized in New York state; by 1900, it was spreading across New England and the upper midwest. (So sulfur cinquefoil probably wasn't around for the Columbian Exposition in Jackson Park in 1893.) It spreads aggressively in disturbed areas.

Potentilla

Potentilla recta

sulfur cinquefoil [Blooms: May-Jul]

Common cinquefoil is a sprawling plant less than a foot tall that produces numerous prostrate stolons up to 3' long. Both the stems and the stolons are initially green but become more reddish. The leaves are alternate and palmately compound with five leaflets, each with serrated margins; the leaflets are three to four times longer than wide. The sparse flowers develop singly on long pedicels that arise from the axil of some compound leaves. They are bright yellow and 1/2" across with triangular sepals shorter than petals; the petals are narrowest at their base and usually rounded at their distal edge. About 20 stamens with yellow anthers (turning reddish with age) surrounded a central mass of styles. Common cinquefoil has flowers and leaves that are superficially similar to those of mock strawberry (Duchesnea indica). However, the leaves of common cinquefoil have extremely sharp-edged, well-defined teeth on the leaf margins (strongly resembling the edge of a hand saw), not the bluntly-tipped teeth of mock strawberry. The five small bracts (leaves) just below the sepals in mock strawberry, each with three pointed lobes at its tip, are present in both the flowers and berries are diagnostic of mock strawberry; they are absent in common cinquefoil. Note that rough cinquefoil’s leaves have three leaflets, common cinquefoil's leaves have five, and prairie cinquefoil's leaves have 7-11 leaflets.

Potentilla

Potentilla simplex

common cinquefoil [Blooms: May-Jul]

Hoptree (a.k.a., wafer ash) is a large shrub with a rounded, irregular crown and (usually) a robust central trunk up to 6" across. Hoptree may produce single-sex (male or female) or bisexual (male and female organs both present) flowers on the same tree. Individual flowers are about 1/4" across, regardless of gender. Perfect (bisexual) flowers have 4-5 greenish sepals, 4-5 narrow, creamy white petals, 4-5 stamens with hairy white bases and yellow anthers, and a single, flattened green pistil. Male flowers are more or less identical but lack the pistil; female flowers are more or less identical but lack the stamens. The fruits are single seeds 1-1.5" long with a broad, flattened, papery wing extending almost all the way around the seed.

Ptelea

Ptelea trifoliata

hoptree [Blooms: May-Jun]

Small-flowered buttercup is a native species that has flowers similar to several other buttercups but is distinguished by its broad range of leaf shapes — other buttercups don't have this wide a variety of leaf shapes on a single plant. The flowers are stalked in groups of one to three on the end of the stems. Each flower is 1/4" across with five lance-shaped or triangular petals that are shorter than the sepals. There are five broadly rounded sepals, a ring of 5-10+ stamens with yellow anthers, and a central mound of green carpels, each with a pistil. After fertilization, the carpels enlarge and the central mound elongates until it is ovoid; the fruits (achenes) are shiny and have small beaks.

Ranunculus

Ranunculus abortivus

small-flowered buttercup [Blooms: Apr-May]

Lesser celadine flowers arise singly from the axils of the upper leaves or on the ends of stems. Individual flowers are about 1" across with three light green sepals half the length of the petals, 7-12 yellow, oblong petals, and a ring of about 30 (yellow) stamens around a central group of about 15-20 (greenish) pistils. This species rarely produces fruit, instead reproducing asexually. The alternative name "Ficaria verna" is occasionally used for lesser celadine, but that name is now considered invalid.

Ranunculus

Ranunculus ficaria

lesser celadine [Blooms: Apr-May]

Hispid buttercup is a native species that gets up to about a foot tall; plants tend to become more sprawling as they grow. Flowers are 3/4-1" across, arising from the leaf axils on stalks with short, appressed hairs. Each flower has five light green sepals shorter than the petals and with long hairs on the outer surface, five shiny, yellow petals, and a ring of 5-10+ yellow stamens around a central mound of yellowish-green pistils. There is often a region at the base of the petals that is translucent and green-tinged. The sepals may lie directly under the petals or may be reflected so they lie parallel to the flower stem. After fertilization, the central mass of the flower enlarges and the other parts of the flower wither and fall away. Maturing fruits are green, shiny, laterally compressed, with a sharply angled margin and long, straight, tapering beaks pointing up at about a 60° angle; the seedhead looks distinctly spikey.

Ranunculus

Ranunculus hispidus

hispid buttercup [Blooms: May-Jul]

Pennsylvania buttercup is a native plant that is formally listed as "imperiled" in Illinois (which is at the southern limit of its range east of the Mississippi). The flowers arise from leaf axils on short stalks. Individual flowers are small (1/8-1/4" across) with five yellowish-green sepals, five shiny, yellow, egg-shaped petals, and a ring of 5-10+ yellow stamens around a central mound of green carpels and pistils. The sepals are longer than the petals, are reflexed back on the flower stem, and are covered with long hairs on the hidden surface. After fertilization, the carpels enlarge and the central mound elongates; individual mature fruits are laterally compressed with straight to sightly curved (but not hooked) beaks. Pennsylvania buttercup tends to prefer wetlands and similar environments.

Ranunculus

Ranunculus pensylvanicus

Pennsylvania buttercup [Blooms: Jul-?]

Cursed crowfoot flowers occur on the ends of the upper stems. Individual flowers are 6-8 mm across with five yellowish-green sepals about the same length as the petals, five (sometimes three or four) yellow, rounded petals, a ring of 5-10+ short stamens with yellow anthers, and a central hemispherical to gumdrop-shaped mass of green pistils. After fertilization, the central mass of pistils enlarges and elongates, producing a cylindrical mass of flat, smooth, kidney-shaped 1 mm long seeds with short, straight beaks.

Ranunculus

Ranunculus sceleratus

cursed crowfoot [Blooms: May-Jul]