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Gypsywort (aka, European bugleweed) is another species native to Europe and Asia. How it came to the New World is unknown, but it has a long history in the botanical literature in Europe (back to the sixteenth century). It strongly prefers wetlands and can often be found in muds. The stem can be as much as 2.5' tall, usually unbranched, light- or yellowish-green, square in section, hairy, and finely grooved. Flowers occur in whorls in the axils of the upper leaves. Each flower is 1/8" across consisting of a green calyx with 4-5 teeth, each longer than the calyx tube, giving the mass of flowers a bristly appearance; a white tubular corolla with four apical lobes, usually with a few pink or purple spots on the lower lip; two stamens; and a style with a bifurcated tip (which can be difficult to see). The fruits are four, concave-topped nutlets cupped in the calyx. This species is known to hybridize with American bugleweed (Lycopus americanus). The medicinal properties of gypsywort are quite controversial; resist the urge to nibble.

Lycopus

Lycopus europaeus

gypsywort [Blooms: Aug-Sep]

Pineapple-weed, unlike it's cousin wild chamomile (Matricaria chamomilla), is probably native to North America, specifically the Pacific Northwest, but has spread widely both here and in Europe. It is a small plant (up to 12" tall); the stems branch frequently. Flowerheads sit on 1/2-1.5" long flower stalks that arise from leaf axils. Each flowerhead is a gumdrop-shaped or conical mass about 8 mm across of greenish-yellow disk florets (125-535+) with four tiny lobes at the apex of the tubular corolla; there are no ray florets. The bracts behind the flowerhead have papery edges. When crushed, both the flowerheads and the foliage give off a pineapple-like fragrance. Sources differ on the biogeography of this plant. Both the USDA Plants and NatureServe Explorer websites say it is an exotic in North America; Wikipedia, the Flora of North America, World Flora Online, and the Illinois Wildflowers website say it's native to North America. Like wild chamomile, the flowerheads of pineapple-weed can be used to make a tea.

Matricaria

Matricaria discoidea

pineapple-weed [Apr-Jul]

Field mint flowers occur in whorls of about 20 above the axils of the upper leaves. Individual flowers are 1/8" long with a green calyx with small triangular lobes; a tubular, lavender, pink, or white corolla with a two-lobed upper lip and a lower lip with 0-3 lobes; four stamens protruding well beyond the tips of the flower; and a style longer than the stamens. The fruit consists of four small nutlets nestled in the flower calyx, each with a single seed. Field mint is a very widely-distributed (circumboreal) plant. Field mint is similar to Virginia bugleweed (Lycopus virginicus) in that both have flowers in whorls in the axils of paired, opposite leaves, but the latter has only white flowers in much sparser whirls with two stamens no longer than the tips of the flower. Field mint could possibly be confused with motherwort (Leonurus cardiaca) but the latter has distinctive three or five lobed angular-cleft leaves and lacks the boldly-protruding stamens of field mint. Finally, some sources (and plant ID apps) identify "Mentha canadensis" as occurring in Illinois and neighboring states. However, both ITIS (https://www.itis.gov/) and the USDA plants database (https://plants.usda.gov/) agree that the name "Mentha canadensis," often applied to this species, is invalid and a junior synonym of Mentha arvensis (field mint).

Mentha

Mentha arvensis

field mint [Blooms: Jun-Sep]

White mulberry is species that was introduced (from Asia) in the 1600's in an attempt to established a silkworm industry in North America; it has since escaped cultivation. Individual trees are usually either male (with staminate florets in drooping, whitish to yellow-green catkins 1-1.5" long) or female (with pistillate florets in less obvious green, erect, cylindrical catkins 1.3-3/4" long), but trees that produce both male and female florets are known. Male florets are 1/4" long with a tiny green or yellowish four-lobed calyx, four stamens, and no pistil or petals. (BTW, the pollen is released by mechanically flinging it into the air via the catapult-like stamens. See Taylor et al. 2006. Sex. Plant. Reprod. 19: 19–24.) Female florets are 1/4" long with a tiny green four-lobed calyx, a single, flattened-oval ovary with two diverging white or reddish styles and no stamens or petals. The fruit is a blackberry-like compound drupe that typically changes color from green to white, but some trees have fruit that continues maturation to red and finally to black. (Those producing black fruit are often referred to var. tartarica, but that name is invalid.) White mulberry can be usually be distinguished from black mulberry by the leaves; the underside of white mulberry leaves is invariably hairless and the top surface smooth, but the underside of red mulberry leaves is covered with small hairs and the upper surface is rough. However, white and red mulberry can hybridize, which can confuse matters significantly.

Morus

Morus alba

white mulberry [Blooms: Apr-May]

Red mulberry is a native (not introduced) species that is easily confused with white mulberry (Morus alba). Red mulberry forms substantial trees 30-60' tall; it is less common in Jackson Park that white mulberry. The trunk is short with greyish-brown bark; the bark is divided into strips by shallow vertical furrows. The leaves are alternate, 4-7+" long and 3-5" across, oval or egg-shaped in outline with serrated margins and a sharp tip. The leaves can either be a simple oval with a pointed tip or a two to three (rarely five) lobed leaf with a pointed terminal lobe; the unlobed leaves are more common. Individual trees are usually either male (with staminate florets in drooping, whitish to yellow-green catkins 3/4-2" long) or female (with pistillate florets in less obvious green, erect, cylindrical catkins 3/4" long), but trees that produce both male and female florets are known. Male florets are 1/4" long with four light green sepals, four stamens, and no pistil or petals. (BTW, the pollen is released by mechanically flinging it into the air via the catapult-like stamens.) Female florets are 1/4" long with four light-green sepals, a single, flattened-oval ovary with two white to reddish, sessile stigmas and no stamens or petals. The fruit is a blackberry-like compound drupe that typically changes color from green to red to finally purplish-black with maturation. White mulberry can be usually be distinguished from black mulberry by the leaves; the underside of white mulberry leaves is invariably hairless and the top surface smooth, but the underside of red mulberry leaves is covered with small hairs and the upper surface is rough. However, white and red mulberry hybridize, which can confuse matters significantly. Leaves may be lobed, but less commonly than in white mulberry. White mulberry can be usually be distinguished from black mulberry by the leaves; the underside of white mulberry leaves is invariably hairless and the top surface smooth, but the underside of red mulberry leaves is covered with small hairs and the upper surface is rough. However, white and red mulberry can hybridize, which can confuse matters significantly.

Morus

Morus rubra

red mulberry [Blooms: ??]

Evening primrose — clusters of yellow flowers occur at the apex of the plant. The flowers are 1-2" across, with four 1/2-1" long green sepals strongly reflected over a long (3/4-2"), green, cylindrical floral tube (the ovary is located just above the leaf axil), four heart-shaped yellow petals, eight stamens, and a single style with an X-shaped stigma. The sepals typically remain connected (in pairs) along one edge until the flower opens. The seedpods develop within the ovary (the base of the elongate floral tube); they are hairy, urn-shaped with rounded edges, and have four or eight small lobes on the apex. The seeds are claimed to remain viable in the soil for up to 70 years. The flowers open at dusk and close early in the day. — — — There are (at least) three evening primroses in Jackson Park — common evening primrose (Oenothera biennis), northern evening primrose (Oenothera parviflora), and hairy evening primrose (Oenothera villosa). They are easily confused with each other. (Judging by the conflicts between the accounts on Illinois Wildflowers [https://www.illinoiswildflowers.info/], Minnesota Wildflowers [https://www.minnesotawildflowers.info/], and Missouri Plants [http://www.missouriplants.com/], even the experts are confused.) All three species have yellow flowers with an X-shaped stigma, reflected sepals, petals with a small notch in their apex, stems that may be red or green, and lance-shaped leaves with short, widely-spaced teeth. Northern evening primrose is distinguished by (1) the presence of a knob or ridge at the tip of each sepal which the other two species lack (2) a seed capsule with four robust, flaring lobes with rounded tips at the apex of the seed capsule, and (3) a stigma that is very robust and almost fills the opening of the flower. Northern evening primrose has green to yellowish-green sepals. Hairy evening primrose (often but not always) has (1) striped or reddish-tinged sepals (check the buds where this character is often easier to see), (2) flowers that turn orange as they begin to senesce (although the reliability of this character is uncertain), and (3) always has glandular hairs covering the ovary that have "pimple-like" bright-red bases; these red pimples may also occur on the stems. All three species are somewhat similar to prairie sundrop (O. pilosella); the latter has very hairy stems and leaves, and translucent lines that radiate from the base of the petals in the flowers.

Oenothera

Oenothera biennis

evening primrose [Blooms: Jul-Oct]

Smallflowered gaura is a spindly, usually unbranched plant that gets 2-6' fall, much of that the flower spike. The stem is round in section, light- to reddish-green, and covered with fine hairs. The leaves are alternate, 2-5" long and 1/4-1" across, lance-shaped, and sessile. The apex of the stem gives rise to a narrow spike of small flowers 1/2-2.5' long. Flowers open from the base of the spike towards the tip with relatively few open at any one time. Individual flowers are about 1/4" across. They consist of four sepals reflected back along the elongated, cylindrical, light-green or red flower stalk/ovary, four spreading white or pink petals, eight stamens, and a long style with a X-shaped (or four-lobed) stigma. The flowers are said to open in the evening and close in the morning. The seed capsules develop from the ovary; they are about 9 mm long. The flowers and flower spike of smallflowered gaura are quite distinctive and unlikely to be confused with any other species.

Oenothera

Oenothera curtiflora

smallflowered gaura [Blooms: Jul-Sep]

As the name suggests, biennial gaura is a biennial. In its first year biennial gaura develops a dense, flat basal rosette; in its second year, multiple stems shoot up from the basal rosette, branching frequently and reaching 3-7' tall. The flower spikes are 4-8" long with flowers opening from the bottom to the top. Each flower is open and airy, 1/2" long and wide, with four white or pink, spoon-shaped, petals deployed around the upper quadrant of the flower; eight long white stamens with yellow anthers and a single long white style with a yellow, X-shaped, stigma emerge at right angles to the fan of petals. Behind the petals is a red or green, hairy, tubular calyx with four sepals whose tips are reflected backwards. The fruits lie on the flower spikes behind the open flowers; they are diamond- or spindle-shaped with a flat-to-conical tip and four large ribs running longitudinally and are covered with fine hairs. Oenothera gaura is almost indistinguishable from large-flowered gaura (Oenothera filiformis, a.k.a., Gaura longiflora), but the latter has larger flowers and hairs on the stems that are curled against the stem (as opposed to straight hairs); I've not identified large-flowered gaura in Jackson Park.

Oenothera

Oenothera gaura

biennial gaura [Blooms: Jul-Sep]

Northern evening primrose flowers are 3/4-1.5" across, have four yellow, heart-shaped petals, eight yellow stamens, and a cross-shaped stigma on a modest style; the stamens are as long or longer than the petals and the stigma is nearly fills the floral opening. At the base of the flower are four sepals 1/2-1" long, that bend back along the 3/4-1.5" long floral tube as the flower develops with pairs of sepals attached along one edge until the flower opens. Only northern evening primrose with a distinct ridge or knob near the tips of the sepals. The seed capsule develops from the ovary; it is 3/4-1.5" long, cylindrical but tapering slightly towards the tip, with four robust, flaring lobes at the tip. — — — There are (at least) three evening primroses in Jackson Park — common evening primrose (Oenothera biennis), northern evening primrose (Oenothera parviflora), and hairy evening primrose (Oenothera villosa). They are easily confused with each other. (Judging by the conflicts between the accounts on Illinois Wildflowers [https://www.illinoiswildflowers.info/], Minnesota Wildflowers [https://www.minnesotawildflowers.info/], and Missouri Plants [http://www.missouriplants.com/], even the experts are confused.) All three species have yellow flowers with an X-shaped stigma, reflected sepals, petals with a small notch in their apex, stems that may be red or green, and lance-shaped leaves with short, widely-spaced teeth. Northern evening primrose is distinguished by (1) the presence of a knob or ridge at the tip of each sepal which the other two species lack (2) a seed capsule with four robust, flaring lobes with rounded tips at the apex of the seed capsule, and (3) a stigma that is very robust and almost fills the opening of the flower. Northern evening primrose has green to yellowish-green sepals and is the only one of the three evening primroses to (sometimes) have reddish color on some or all of the midvein of the leaves. Hairy evening primrose (often but not always) has (1) striped or reddish-tinged sepals (check the buds where this character is often easier to see), (2) flowers that turn orange as they begin to senesce (although the reliability of this character is uncertain), and (3) always has glandular hairs covering the ovary that have "pimple-like" bright-red bases; these red pimples may also occur on the stems. All three species are somewhat similar to prairie sundrop (O. pilosella); the latter has very hairy stems and leaves, and translucent lines that radiate from the base of the petals in the flowers.

Oenothera

Oenothera parviflora

northern evening primrose [Blooms: Jun-Jul]

Prairie sundrop is similar to evening primrose (O. biennis) but more delicate and only about 2' tall. The flowers are ~2" across, pale golden-yellow, with translucent lines that radiate from the petals' bases. The flower is attached to a 1/2-1" long floral tube whose base is the ovary, nestled in a leaf axil. The floral tube is covered by four hairy sepals; the four petals are heart-shaped; the stamens are long, yellow, with large yellow anthers; the style extends well beyond the stamens and has a large, X-shaped stigma. Each flower lasts only about a day. The fruits form from the ovary which often have four prominat wings. The fruits are ~1/2" long, four-angled or ridged, club-shaped, with four internal chambers filled with 1 mm long seeds.

Oenothera

Oenothera pilosella

prairie sundrop [Blooms: Jun]

Hairy evening primrose produves an elongating spike of flowers arises from the apex of the stem; flowers bloom near the tip while older flowers and seed capsules develop below. Individual flowers are 3/4-1.5" across; they sit on a long floral tube with the ovary at its base (attached to a leaf axil). The flowers have four yellow, heart-shaped petals, eight yellow stamens, and a cross-shaped stigma on a modest style; at the base of the flower are four sepals 3/8-3/4" long, reflected back along the floral tube as the flower develops with pairs of sepals attached along one edge until the flower opens. The sepals are often red-striped or red-tinged. Note the long, hairy floral tube below the sepals, the reddish stem, and glandular hairs with red bases on the ovary. The seed capsule develops from the ovary; it is up to 1.75" long, cylindrical but tapering slightly towards the tip, with four tiny lobes at the tip. — — — There are (at least) three evening primroses in Jackson Park — common evening primrose (Oenothera biennis), northern evening primrose (Oenothera parviflora), and hairy evening primrose (Oenothera villosa). They are easily confused with each other. (Judging by the conflicts between the accounts on Illinois Wildflowers [https://www.illinoiswildflowers.info/], Minnesota Wildflowers [https://www.minnesotawildflowers.info/], and Missouri Plants [http://www.missouriplants.com/], even the experts are confused.) All three species have yellow flowers with an X-shaped stigma, reflected sepals, petals with a small notch in their apex, stems that may be red or green, and lance-shaped leaves with short, widely-spaced teeth. Northern evening primrose is distinguished by (1) the presence of a knob or ridge at the tip of each sepal which the other two species lack (2) a seed capsule with four robust, flaring lobes with rounded tips at the apex of the seed capsule, and (3) a stigma that is very robust and almost fills the opening of the flower. Northern evening primrose has green to yellowish-green sepals. Hairy evening primrose (often but not always) has (1) striped or reddish-tinged sepals (check the buds where this character is often easier to see), (2) flowers that turn orange as they begin to senesce (although the reliability of this character is uncertain), and (3) always has glandular hairs covering the ovary that have "pimple-like" bright-red bases; these red pimples may also occur on the stems. All three species are somewhat similar to prairie sundrop (O. pilosella); the latter has very hairy stems and leaves, and translucent lines that radiate from the base of the petals in the flowers.

Oenothera

Oenothera villosa

hairy evening primrose [Blooms: Aug-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]

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]

English plantain is a Eurasian exotic that is a familiar lawn weed, one with a wirelike, leafless, five-angled flower stalk 6-18" tall. At the tip of the flower stalk is a 1/2-3" long cylindrical flower spike, initially grey-green but turning brownish as the flowers open. Individual flowers have four sepals, and four petals, but their most obvious character is the long filamentous stamens with white anthers which protrude in all directions from the flower spike. The styles are white, filamentous, and fuzzy. The flowers usually open sequentially from the bottom to the top of the flower spike, first as functional females with protruding styles, then as functional males with prominent stamens; the flower spikes thus typically consist of (from top to bottom): (1) unopened buds, (2) flowers with functional styles, (3) flowers with functional stamens, (4) developing seed pods. The flowers are wind-pollinated.

Plantago

Plantago lanceolata

English plantain [Blooms: May-Aug]

Common plantain is an introduced plant commonly found in lawns and disturbed areas. The flower stalks are erect, 4-20" long; the lower third is green and unadorned while the upper two-thirds is densely covered with 1/8" green flowers. Individual flowers consist of four green sepals with a green keel and membranous margins above a single green bract, four filamentous stamens with tan to purplish anthers, a single white style, and a four small, papery, petals. The flowers are wind-pollinated. The fruits are rounded, egg-shaped capsules about 1/8" long. Common plantain is nearly indistinguishable from (the native) black-seeded plantain (Plantago rugelii); the two species differ only in the details of the sepals and seed pods. (Common plantain's seed capsule is egg-shaped and splits around the middle; black-seeded plantain's seed capsule are 2-3 times longer than wide splits nearer the bottom.) One, more ephemeral, character may help distinguish the two species in the field. According to Minnesota Wildflowers, the base of the leaf stalks of the native species (Rugel's plantain, P. rugelii) are dark red or purple in color; the base of the leaf stalks of the exotic common plantain (P. major) are uniformly green. Rugel's plantain is probably as common and tolerant of a range of habitats as common plantain, but specimens of this plant tend to be reflexively referred to "common plantain."

Plantago

Plantago major

common plantain [?-Aug]

In late spring and early summer, curly pondweed produces both flowers and turions (a detachable, dormant bud, a.k.a. a "winter bud"). Cylindrical flower spikes 1-1.5" long arise from the tips of the stems or the axils of upper leaves; peduncles up to 3" long hold the flower spikes just above the water. Each flower spike may have 3-5 whorls of flowers. Individual flowers are tiny (3 mm across); they consist of four greenish-brown or greenish-red sepals, four stamens with a ladle-shaped appendage, and four ovules topped by a four-part style. Flowers may be pollinated by either wind or water. Fertilized ovules produce a dry seed (a maximum of four per flower) that is generally oval but asymmetrical in detail with a knobby keel along one edge and a long, curved beak or tooth at the opposite end. Seed germination has never been observed. Simultaneously, the plant produces turions — rosettes of small, holly-like leaves that overall have a cone-like appearance — from the tips of stems and leaf axils. After the fruits and the turions are released, the rest of the plant degenerates over the course of the summer. The turions sink to the bottom of the water body and root, forming small plants that overwinter.

Potamogeton

Potamogeton crispus

curly pondweed [Blooms: May-?]

Slender mountain-mint flowers occur in small terminal clusters at the tips of the upper stems with distinctive very long, narrow bracts with spine-like tips just beneath the clusters; the bracts are densely covered with short, curled hairs on the blade and longer, bristly hairs along the margins. Individual flowers are tubular, white with scattered purple dots, and about 1/4" long; there is a calyx that is divided several slender green lobes. The corolla is divided into two parts, an upper lip and a lower lip that is divided into three lobes. The four stamens and two styles are also white, but the anthers are purple. The styles have a bifurcated stigma. Slender mountain mint is very similar to Virginia mountain mint (Pycnanthemum virginianum), but several characters make it straightforward to distinguish them. Leaves on slender mountain mints are always less than 1/4" wide and the stems are hairless; Virginia mountain mint will have the larger leaves more than 1/4" wide and has lines of white hairs on the stems. Slender mountain blooms earlier than Virginian mountain mint, but the blooming period of the two species overlaps. All parts of slender mountain mint give off a strong mint-like odor when crushed, but please restrain yourself from excessive foliage-crushing — it's not polite.

Pycnanthemum

Pycnanthemum tenuifolium

slender mountain-mint [Blooms: Jun-Aug]