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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]

Ditch stonecrop is native to North America; its range includes the majority of the states in the U.S. and the provinces in Canada. It is a small (1-2' tall) plant with green or red stems, usually unbranched. Cymes of flowers 1-3" across arise from the upper stems, each cyme with 2-4 spreading flowering stalks; flowers are restricted to only one side of the flower stalks. Individual 1/4" flowers are yellowish-green to white, have five spreading, green sepals, ten stamens with cream-colored or yellow-orange anthers, and five beaked carpels, each with a single style and a green stigma; petals are completely absent. (The carpels look rather like a teapot with no handle and a very wide spout, or like a "duck" wine decanter. Look it up.) The carpels become the seed capsules; they turn bright red when mature. Ditch stonecrop prefers wet habitats (like ditches). It is completely unrelated to biting stonecrop (Sedum acre).

Penthorum

Penthorum sedoides

ditch stonecrop [Blooms: Aug-?]

At the apex of the stems and branches of wild dill are compound umbels of small white flowers; the umbels are about 6" across and have 12 umbellets that are widely spaced from each other. An umbellet is about 1" across and contains 7-21 flowers. Individua flowers are about 3 mm (1/8") across, consisting of 5 small, triangular, green sepals; 5 petals, each notched at the tip; (ideally) 5 stamens with white anthers; and a hairless ovary formed from two fused carpels, each with a short style. The stamens are fragile and often fall off, so there may be less than five stamens present. The fruit is an elongated schizocarp 3-5 mm long with a longitudinal groove that splits to release laterally flattened, wingless, brown to black seeds. Often, the remnants of the styles persist at the apex of the fruit.

Perideridia

Perideridia americana

wild dill [Blooms: Jun]

Waterpepper is a rather spare plant, 1-2' tall which needs close observation to be appreciated. 2-7" long spikes of minute flowers, only a few of which are open at any one time, terminate the upper stems; the flower spikes often nod or droop. Each greenish-white flower is ~1/8" long with five tepals covered with glandular pits (see below), green towards the base, brilliant white at the tips, 4-6 white stamens, and 2-3 white styles. The flowers never open very far. P. hydropiper is distinguished by (usually) reddish stems and the presence of tiny glandular pits (often pale yellow or brown, and only visible with magnification) on the greenish portions of the tepals. Cultivated varieties of waterpepper have been eaten in Japan and Europe, but the wild form produces a variety of oils that can cause skin (including the oral mucosa) irritation and swelling.

Persicaria

Persicaria hydropiper

waterpepper [Blooms: Aug-Sep]

Pale smartweed is a very tall smartweed (2.5-4') characterized by long, dense, drooping, whitish flower clusters and the absence of bristles on the leaf sheaths (ocreae). Stems terminate in drooping flower spikes 2-8" long, densely packed with small (1/8" long) flowers. Individual flowers have 4-5 greenish-white to pinkish tepals, 5-6 stamens with pink anthers and two styles. Because the flowers open only at their tips, the reproductive structures are difficult to observe. After fertilization, a three-angled seed, 2 mm across, develops nestled in the tepals. This is the largest smartweed that occurs in Illinois. Pale smartweed prefers wet soils (e.g., the shores of water bodies). Pale smartweed is similar to Pennsylvania smartweed (Persicaria pennsylvanica) but that plant has erect, cylindrical flower spikes and the flowers are pink or reddish.

Persicaria

Persicaria lapathifolia

pale smartweed [Blooms: Jul-Oct]

Creeping smartweed is another weedy exotic, but its charm increases as you look closer. The flower spikes are 1.5" long and <1/4" wide; they are covered with tiny (~1/8" long) flowers with five pink tepals, only a few of which are open at any one time. (Petals are absent.) There are five stamens with pink or yellow anthers and three styles hidden within the flower; they are visible only with difficulty. At the base of each flower is a small membranous sheath with bristles as long or longer than the flowers (not present on all flowers). After fertilization, a three-angled seed that tapers to a point on each end develops nestled in the tepals. This is an Asian species that was introduced to North America around 1910 near Philadelphia and reached Illinois in the 1940's; it strongly prefers wet soils. Creeping smartweed resembles lady's-thumb (Persicaria maculosa), but creeping smartweed's sprawling habit and the long bristles associated with the flowers are distinctive.

Persicaria

Persicaria longiseta

creeping smartweed [Blooms: May-Oct]

Lady's-thumb is an exotic, native to Europe, but has a long history in North America — it was first reported from the Great Lakes in 1843. Flower spikes (racemes) are 1/2-1.5" long and densely covered with tiny (1/8" long) pinkish-white flowers; flower color is quite variable, even within a single flower spike. The flowers are "shy" and often open only at the tips of the 4 or 5 sepals (there are no petals); both the six stamens and the single style (divided into three towards the distal end) remain hidden. Seeds are black; they develop singly within the persistent sepals and remain largely hidden by the sepals; they can be found on flower heads still blooming. Lady's-thumb prefers wet habitats.

Persicaria

Persicaria maculosa

lady's-thumb [Blooms: Jun-Sep]

Pennsylvania smartweed flower spikes are 3/4-2" long, distinctly cylindrical with a blunt tip, erect, and densely covered with white, pink, or reddish flowers, only a few of which are open at any time. The peduncle of the flower spike is usually covered with short glandular hairs. Individual flowers are ~1/8" long, and have five tepals (white, light pink, or rose pink), 6-8 stamens with yellow, white, or pink anthers and two styles. Pennsylvania smartweed is a particularly variable species and may be difficult to identify unequivocally. If the stems zig-zag between nodes, if the flower stalks' peduncules are covered with glandular hairs, or if the flower spikes are short, cylindrical and erect, the specimen is likely to be Pennsylvania smartweed, but any or all of these features may be missing.

Persicaria

Persicaria pensylvanica

Pennsylvania smartweed [Blooms: Jul-Sep]

Dotted smartweed (Persicaria punctata) is a very common smartweed in Illinois wetlands. The upper stems produce spike-like racemes 2-6" long with white to greenish-white flower buds and flowers sparsely distributed along their length. Individual flowers are about 1/8" long with five white tepals covered with glandular depressions (best viewed with a hand lens). There are 6-8 stamens with red or pink stamens; the single style divides into two or three branches near its base. The flowers only open at their tips. The single seed is three-angled, oblong, and shiny brown to black; it remains tightly enclosed in the tepals as it develops. In Jackson Park, only dotted smartweed and waterpepper (Persicaria hydropiper) have glandular depressions on the surface of the flower tepals.

Persicaria

Persicaria punctata

dotted smartweed [Blooms: Aug-Sep]

A relative of the smartweeds and lady's thumb, jumpseed consist of a single, unbranched stem 1-2' tall with an apical inflorescence that can add an additional 16". Flowers are brilliant white, tiny (<3/16" across), with 4 sharply pointed petals (actually, sepals); 4-5 white stamens and a style are visible if you have really good eyesight. Flowers are widely spaced along the flower stalk on very short green stalks. Jumpseed is easy to tell from other smartweeds by the very long inflorescence with sparsely distributed flowers and very large leaves.

Persicaria

Persicaria virginiana

jumpseed [Blooms: Jul-Aug]

Sweet mock-orange inflorescences are racemes with 5-7 fragrant flowers; the most basal pair of flowers arise directly from the leaf axils. Individual flowers are 1-1.5" across, have four triangular green sepals, four brilliant white petals, 20-50 white stamens with orange anthers, and four white styles with yellow-orange stigmas. The styles are closely appressed proximally, separate distally.

Philadelphus

Philadelphus coronarius

sweet mock-orange [Blooms: May-Jun]

Cleft phlox flowers are supported by 1" pedicels, are 3/4" across, white or pale violet, with a tubular corolla that flares into five petal-like lobes that are each deeply cleft at their tips; the throat is very narrow. A three-lobed stigma and the orange anthers of the stamens lie just within the opening to the throat of the flower. Cleft phlox is endemic to the Midwest. The cleft petal lobes distinguish cleft phlox from all other Phlox species.

Phlox

Phlox bifida

cleft phlox [Blooms: Apr-?]

Woodland phlox is a 1-1.5' tall plant with a fuzzy to hairy stem, light green or reddish brown in color. Leaves are opposite (or sometimes in a three-leaf whorl), sessile or clasping the stem, three times longer than wide, lance-shaped with smooth margins, and fuzzy to hairy overall with short hairs around the margins. The flowers are 1" across, pale blue-violet, lavender, or (rarely) white, and with a long, narrow tubular throat that abruptly flares into five petal-like, spoon-shaped lobes. The calyx is green or reddish-green, hairy, with five long, narrow teeth almost half the length of the flower, spreading near their tips. The five stamens and style are hidden within the throat. Woodland phlox has relatively broader leaves than other Phlox species and has a more intense blue-violet (and less pink) color.

Phlox

Phlox divaricata

woodland phlox [Blooms: Apr-May]

Smooth phlox is a 1-2' tall plant with an unbranched, hairless stem topped with a slightly domed cluster of 3-20 pink or lavender flowers. Each flower is about 3/4" across and has a long, tubular throat that abruptly flares into five petal-like lobes; each lobe is wedge-shaped and overlaps the next lobe clockwise. The calyx (also hairless) consists of five triangular segments that taper rapidly to sharp points; the calyx is <1/3 the length of the corolla tube. The five stamens and single style with a three-part stigma either lie within the corolla tube or are just visible in the throat. After fertilization, a narrow seed capsule filled with numerous seeds fills the persistant calyx. Smooth phlox prefers moist to wet habitats. Smooth phlox flowers resemble prairie phlox (P. bifida) but the latter species is quite hairy on the stems, leaves, and the exterior of the flower (the calyx); smooth phlox is hairless. Checking the hairiness (or lack thereof) of the calyx is the quickest way to tell prairie phlox from smooth phlox.

Phlox

Phlox glaberrima interior

smooth phlox [Blooms: Jun-Aug]

Prairie phlox is a compact, single-stemmed, plant 1/2-1.75' tall with (typically) a dome-shaped cluster of flowers at the apex. Individual flowers are 1/2-3/4" across, pink or lavender (rarely white); the corolla is tubular with five wedge-shaped, petal-like lobes often with darker markings (nectar guides) near the throat; the corolla is hairy on all external surfaces. The throat is very narrow; the five stamens with yellow anthers are recessed but just visible. The very short, tubular, hairy calyx base is green, with five long, narrow teeth that extend parallel to the narrow throat (also hairy) of the corolla. The fruit is oval and shorter than the calyx (in which it develops); when ripe, the capsule splits explosively, flinging the seeds in all directions. The species name ("pilosa") means "hairy" in Latin, and this species is indeed hairy on almost every surface. Prairie phlox flowers resemble smooth phlox (P. glaberrima) and, to a lesser extent, woodland phlox (P. divaricata), but the former species is quite hairy on the stems, leaves, and the exterior of the flower (the calyx); smooth phlox is hairless. Checking the hairiness (or lack thereof) of the calyx is the quickest way to tell prairie phlox from smooth phlox; checking the hairiness of the exterior of the corolla tube will distinguish woodland phlox (hairless) from prairie phlox (hairy).

Phlox

Phlox pilosa

prairie phlox [Blooms: Apr-Jun]

Giant reed is a grass that grows 4-16' tall (the tallest native grass in Illinois), often in dense, clonal stands. The culm (stem) is greyish-blue or light green; the base of the culm may be 15 mm (about 5/8") across. The culm ends in a panicle up to 1.5' long and half as wide of spikelets. When the florets are blooming, the panicle of spikelets has a reddish, silky appearance. Each spikelet is 12-17 mm long containing 3-7 florets. At the base of the spikelet is a pair of scale-like glumes (bracts) at about a 30° angle to each other; the base of the upper glume is nested inside the base of the lower glume, and both have a long, tapered, pointed tip. The glumes are typically 4-6 mm (1/4") long. Above the glumes, along the central axis of the spikelet (rachilla) are a series of progressively-shorter bracts (lemma and palea — more delicate versions of glumes — surrounding each floret) and tufts of silky hairs 1 cm long attached to the rachilla and obscuring the florets. The most basal floret is either sterile or is staminate; the remaining florets containing both male and female reproductive organs (= "perfect"). Staminate and perfect florets contain 1-3 stamens with purple anthers; perfect florets also have two long, feathery styles. The florets are wind-pollinated. After fertilization, individual seed grains replace the florets.

Phragmites

Phragmites australis

giant reed [Blooms: ?early-midsummer]