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French grass flowers are 1/4" long, pea-like, with a short, green, tubular calyx with five teeth, and five blue, purple, or white petals — a single upright banner, two forward-projecting wings, and two closely-appressed petals that make up the keel (largely hidden by the wings). Ten stamens and the style are nestled inside the keel. Seedpods are about 1/2" long with a stout, pointed "beak."

Orbexilum

Orbexilum onobrychis

French-grass [Blooms: Jun-Jul]

Star of Bethlehem's unopened flower buds bear alternating green and white triangles on the enclosing tepals that make the species easy to ID even before the flowers open. Flowers are about 3/4" across with six tepals, white on the top surface and the margins of the underside, green along the centerline of the tepal's underside; six stamens with yellow to brownish anthers whose filaments are flattened to form a visually-striking picket fence topped by sharp points; and a single pistil with a six-ridged yellow ovary and a single yellowish-green style. The fruits are three-celled with six exterior ridges, initially looking like the bottom of a miniature green bell pepper. The flowers produce lots of nectar; they tend to open before noon and close before sunset (or much earlier on cloudy days). Star of Bethlehem is an escapee from cultivation and is competitively quite aggressive. This species produces toxic cardiac glycosides throughout the plant but especially in the flowers and bulbs; it has been reported to have poisoned unwary sheep.

Ornithogalum

Ornithogalum umbellatum

star of Bethlehem [Blooms: May]

Aniseroot tends to be an understory plant, 1-2.5' tall. Individual flowers are tiny (1/8"), grouped in distinct compound umbels, each with several narrow, lance-shaped bracts with hairy margins at the base of the umbel. The flowers have a tiny green calyx without sepals, five white petals with incurled tips, five stamens with white anthers, and a pistil with a divided white style (longer than the petals — about 2 mm). The fruit is a hairy, narrow, arched seedpod about 1" long; the two styles (and, less commonly, petals and stamens) persist at the tip of the seedpod for part of the maturation. Aniseroot is very similar to sweet cecily (Osmorhiza claytonii), but aniseroot has more flowers (8-16) in each umbel than does sweet cecily (4-7) and the two styles in the flower are short and dumpy (shorter than the petals) in sweet cicely and much longer (longer than the petals) in aniseroot. The stems and stalks (except the umbel stalks) are densely covered with fine, short hairs or no hairs in aniseroot, long, spreading hairs in sweet cecily. The crushed leaflets smell like — surprise! — anise in aniseroot.

Osmorhiza

Osmorhiza longistylis

aniseroot [Blooms: Apr – Jun]

Hop hornbeam (aka, ironwood) flowers are in the form of catkins, with separate male and female inflorescences. Male (staminate) catkins are 1-2" long, narrowly cylindrical, often occurring in groups of three; male flowers have three stamens. Female (pistillate) catkins are 1/2" long and stubby, occurring singly at the tips of branches; individual flowers consist of a basal, green bract and two red, thread-like styles. The flowers are wind-pollinated. The fruit is 1.5-2.5" long and 3/4-1" wide, superficially similar to the fruit of hops vines (Humulus lupulus), with flattened, spindle-shaped nutlets 5-8 mm long hidden inside yellowish, papery, inflated sacs 1/3-1" long.

Ostrya

Ostrya virginiana

hop hornbeam [Blooms: Apr-May]

The yellow-flowered wood-sorrels in general (of which yellow wood sorrel is one) are difficult to distinguish and have given rise to much taxonomic confusion. (I.e., it's not just us; even the pros have problems. Read on.) Flowers are 3/8-1/2" across; they have five light green sepals, shorter than the petals, five yellow petals with rounded tips, ten stamens with yellow anthers, and a single pistil with five styles fused except at their tips. These flowers often have a ring of red lines around the throat (like yet another species, O. illinoensis). The seed capsules are 1/4-1/2" long, banana-shaped, erect, hairy, and five-sided; the capsules use explosive seed dispersal (like jewelweed and wild geranium) to scatter the contained seeds. This species is very similar to another yellow wood sorrel, Oxalis dillenii; see https://www.minnesotawildflowers.info/flower/yellow-wood-sorrel for details on how to distinguish the two. (A good hand lens or a microscope are required.)

Oxalis

Oxalis stricta

yellow wood-sorrel [Blooms: May-Sep]

Cowbane is a spindly, sparse plant 2-5' tall. At their apex, the stems produce shallowly dome-shaped compound umbels 3-5" across of 10-25 umbelletes of 10-20 small white flowers each. Individual flowers are about 3 mm across; each has a short calyx, five white petals with notched tips, five stamens with white anthers, and a central greenish or white ovary with two styles. The fruit is a elongate (1/4" long), flattened oval with wings on the flattened edges, longitudinal stripes/ribs and, initially, with the remnants of the two styles at their tips; when mature it splits, releasing two seeds. Cowbane prefers wet soils. As you might suspect from the name, it is toxic if eaten.

Oxypolis

Oxypolis rigidior

cowbane [Blooms: May-June]

Butterweed stems produce a flattened panicle of flowers about 6" across with a single series of bracts (phyllaries) surrounding the base of the flowerhead. Individual flowerheads are 1/2" across with 5-15 yellow, narrowly-oblong pistillate ray florets and 35-50+ yellow, tubular disk florets with five apical lobes a single style that extends just past the anthers, and five stamens attached to the inside of the tubular corolla; the disk is 4-5 mm across. The fruit is a single, five-angled seed with a tuft of white hairs (like a dandelion). Butterweed contains toxic compounds (probably pyrrolizidine alkaloids) which deter most mammalian herbivores (although some domestic herbivores do eat it and suffer the consequences). According to ILW, butterweed was typically restricted to southern Illinois, with a few recent occurrences in central Illinois. Apparently, it has now made its way to Cook County. 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. With one exception, the flowers don't help to distinguish them; however, the petals of butterweed, seen from behind, have a strap-shaped blade with 2-3 teeth at the distal end and a narrow tube (the corolla tube) about a quarter the length of the strap connecting the strap to the rest of the flower (not present in the ragworts). In general, 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 glabella

butterweed [Blooms: May-Jun]

Balsam ragwort flowerheads are 1/2-3/4" across 8 or 13 (rarely, 0) pale yellow ray florets and 50-65+ golden-yellow disk florets. Both disk and ray florets are perfect (i.e., have both male and female reproductive structures). The disk florets are tubular with five lobes at their apex; they have a single style and five stamens. At the base of each flowerhead is a single series of bracts (phyllaries); the phyllaries are light green, fading to pale purple at their tips. Butterweed (Packera glabella), balsam ragwort (Packera paupercula), and prairie ragwort (Packera plattensis) are easy to confuse — all boom 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 paupercula

balsam ragwort [Blooms: Apr-May]

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]

Mature wild quinine plants are 2-3' tall. On the flowering stalks (and the side branches) are flat topped clusters of white, button-like flowerheads about 3/8" across. (The Illinois Wildflowers website considers them "similar to a head of cauliflower.") Flowerheads are composed of 15-35 disk florets, often with blackish, club-like stamens poking out; the 5-6 ray florets bear a tiny, cup-shaped petal and a pistil with a bifurcated stigma. No other wildflower in Illinois has flowerheads anything like wild quinine; common and widespread in Jackson Park.

Parthenium

Parthenium integrifolium

wild quinine [Blooms: May-Aug]

Virginia creeper produces panicles of 80-150 flowers opposite leaf nodes; the panicles are broader than long and have a distinct central axis. Individual flowers are 1/4" across, green, with five petals, five white stamens with yellow anthers, and a single stout, cone-shaped style. Flowers may have only stamens, only pistils, or both pistils and stamens. The petals have a raised margin (less so than woodbine) and are reflected backwards around the flower stalk. The fruit is a fleshy berry that is initially green but becomes blue-black with maturation; the flower stalks become orange-red or red as the fruit matures. The clusters of the fruit are reminiscent of a bunch of grapes. Opposite the leaf nodes are tendrils with as many as 10 branches; the tendrils end in distinct (adhesive) pads. Virginia creeper plants growing on trees produce aerial roots with a distinct "beard" of rootlets. Woodbine (Parthenocissus vitacea) also has palmate leaves with five leaflets, very similar to Virginia creeper (P. quinquefolia), but lacks the distinctive "bearded" aerial roots with short rootlets 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 ten 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 creeper 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 distinct species and I'll consider that to be correct here.

Parthenocissus

Parthenocissus quinquefolia

Virginia creeper [Blooms: June]

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]

Calico penstemon (aka, long-sepaled penstemon) is a typical penstemon/beardtongue — 1-3' tall with an unbranched stem and a panicle of flowers at the apex of the stem. Flowers are about 1" long, with a calyx with five long (5-12 mm), narrow (1-2 mm) lobes, a tubular corolla with two upper lobes and three lower lobes on the aperture, and four stamens and a single style, all enclosed by the corolla. The corolla's exterior is light purple or light violet and covered in fine hairs; the interior of the corolla is white and smooth, without ridges. The lobes on the lower lip of the corolla do not protrude beyond the lobes of the upper lip. Calico penstemon is fairly rare in Jackson Park.

Penstemon

Penstemon calycosus

calico penstemon [Blooms: Jun-Jul]

Foxglove beardtongue's inflorescence consists of 3-6 pairs of panicles at the apex of the stems. Individual flowers are white or (less often) pink with a green or maroon calyx, five narrowly triangular lobes, and a tubular corolla that flares abruptly distal to the calyx. The corolla's aperture bears five lobes (two above on the upper lip, three below on the lower lip) with pink or purple nectar guides inside the tube. The filament of a sterile stamen (a "staminode") bearing sparse yellow hairs runs along the midline of the lower half of the corolla, while the filaments of the other four stamens wrap around the inside of the corolla like ribs in a ribcage, with the black anthers positioned on either side of the midline of the upper corolla. A single style runs along the upper midline between the black anthers to emerge between the two upper aperture lobes. The fruit is a bullet-shaped capsule about 1/2" long nestled in the persistant calyx. The calyx, flower stalks, and the flowers themselves are densely covered by glandular hairs; the main stems and leaves are hairless. Foxglove beardtongue is ubiquitous in Jackson Park.

Penstemon

Penstemon digitalis

foxglove beardtongue [Blooms: May-Jul]

Slender beardtongue (aka, lilac penstemon) is another beardtongue/penstemon that is uncommon in Jackson Park. The stems are unbranched, green or purple, and may or may not bear hairs. There are both basal and stem leaves. The basal and lower stem leaves are 1-3" long and 1/2" wide, variable in shape and leaf margins; the stem leaves are smaller and minutely toothed. Individual flowers are pinkish, purple, or pale violet, about 3/4" long; they are comprised of a green calyx with five triangular lobes and a tubular corolla that is abruptly inflated in the more distal two thirds of the flower. The lower lip of the corolla has three lobes that extend down and out from the aperture the upper lip has two smaller, erect lobes. The interior of the corolla is white with several dark purple lines that act as nectar guides. The filament of a sterile stamen (a "staminode") bearing sparse yellow hairs runs along the midline of the lower half of the corolla, while the filaments of the other four stamens wrap around the inside of the corolla like ribs in a ribcage, with the black anthers positioned on either side of the midline of the upper corolla. A single style runs along the upper midline between the black anthers. The fruit is a more or less bullet-shaped capsule nestled in the persistant calyx. The calyx, flowers, and flower stalks are all covered with glandular hairs; the stems and leaves are not.

Penstemon

Penstemon gracilis

slender beardtongue [Blooms: Jun-Jul]