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Wild chamomile stems terminate in a daisy-like flowerhead, 1-2" across. Flowerheads consist of 10-25 white, fertile (pistillate) ray florets that tend to droop slightly and a gumdrop-shaped central mass of 250-550+ yellow disk florets with both male and female reproductive structures. Individual disk florets are tubular. Behind the flowerhead are one to three series of light green, lance-shaped bracts with membranous edges. Wild chamomile can be distinguished from similar plants like ox-eye daisy (Leucanthemum vulgare) by its multiply-pinnate, slender lobes leaves and the fact that the flowerhead is actually hollow; when crushed they produce a pleasant, fruity fragrance. Wild chamomile is closely related to pineapple weed (Matricaria discoidea) but the two can't be confused.

Matricaria

Matricaria chamomilla

wild chamomile [Blooms: May-Jun]

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]

Water chickweed (aka, giant chickweed) is an exotic from Europe; it resembles a much-enlarged enlarged (potentially 1-2.5' tall vs. a few inches although the stalk sprawls) version of our common chickweeds. Flowers may occur as singletons arising from the leaf axils or clusters of a few flowers at the end of the stems. Each flower is 1/2" across; it has five fuzzy, green, oval sepals slightly shorter than the petals; five white, deeply-cleft petals that look like ten; 10 stamens with white anthers; and a green ovary with five short, arching styles. The stems and the 1" long pedicels of the flowers are both very fuzzy. The fruit is an ovoid seed capsule nestled in the persistant sepals which hangs down from the pedicel when ripe; it could easily be mistaken for a bud if you didn't notice it was pointed down.

Myosoton

Myosoton aquaticum

water chickweed [Blooms: May-Jun]

Glade mallow flowers fill the entire apex of the plant in multiple clusters (panicles). Each plant produces only male or only female flowers. Both male and female flowers are about 1/2-3/4" across with 1" long pedicels, a short, light green, tubular calyx bearing five broad teeth around the edge, and five white petals. To this general pattern, male flowers add 16-20 stamens fused basally; the free ends are separated into filaments bearing tan or pink anthers. Female flowers add to the basic flower a compound style with 6-10 white, twisted, thread-like branches. The fruits are round, fist-like clusters of wedge-shaped segments (up to 10), each containing a single seed. Glade mallow occurs in only seven states. It is listed as "vulnerable" in Illinois, Iowa, Wisconsin, and Ohio; it is "imperiled" in Indiana and Minnesota and critically imperiled in Maryland. Glade mallow prefers moist habitats. Populations in Jackson Park have been noticeably expanding over the last few years; be grateful.

Napaea

Napaea dioica

glade mallow [Blooms: Jun-Aug]

Poet's daffodil is an escapee from domestic gardens. The species is native to Central and Southern Europe; it is said to have been cultivated by the Greeks in the 3rd century BCE. The leaves are basal, blue-green, awl-shaped, up to 20" long and 1/2" wide, parallel-veined with smooth margins. The unbranched stems can get up to 1.5' tall, each with a solitary flower at their apex. The 2-3" diameter flowers have six white tepals with a yellow, crinkled central corona (often red-rimmed) in the form of a cup surrounding the reproductive organs (six stamens, only three of which are easily visible externally, and a single style with a three-lobed stigma). Fruits are rarely produced. The corona is relatively longer and bigger in diameter in wild daffodil than it is in poet's daffodil. Keep pets (and small children) away from poet's daffodil — if ingested, it induces severe vomiting.

Narcissus

Narcissus poeticus

poet's daffodil [Blooms: Apr-May]

Wild daffodil is just a daffodil that has escaped cultivation — the species is native to western Europe. Wild daffodil stems get up to 20" tall; they are unbranched with a single flower at their apex. The leaves are basal, 8-20" long, about 1/2" wide, flat, and blue-green in color. The stem and flower bud are initially aligned, but the upper part of the stem becomes plastic for a short period, deforming to reorient the upper part of the stem (and the bud) to a position perpendicular to most of the stem. Each flower consists of a conical basal section (think "calyx") with six spreading, yellow lobes (equivalent to tepals). Where the lobes/tepals bend backwards, a tubular, yellow, crinkled corona perpendicular to the tepals surrounds the reproductive structures (six stamens and a single style with a three-lobed stigma). Fruits are rarely produced. The corona is relatively longer and bigger in diameter in wild daffodil than it is in poet's daffodil. Keep pets (and small children) away from wild daffodil — if ingested, it induces severe vomiting.

Narcissus

Narcissus pseudonarcissus

wild daffodil [Blooms: Mar-May]

Spatterdock is an archaic-looking water lily, and for good reason — the genus is at least 50 million years old. Single flowers are borne on the tips of stout pedicels. The buds are enclosed in three green outer sepals which reveal three underlying yellow sepals when the flower opens. An open flower is 1-3" in diameter with the opening 40-50% of that total. The yellow petals have been reduced to oblong scale-like structures inside the flower below the stamens. The large, mushroom-shaped pistil takes up most of the center of the flower the stigmatic disc visually dominating. The very numerous, oblong, truncate, ribbon-like stamens lie immediately below the large, flattened disc-like stigma; they look nothing like the delicate stamens common in most flowers. The fruit is flask-shaped, constricted below the pistil, boldly ribbed and green on the globular body; the remnant of the stigmatic disc is red-rimmed.

Nuphar

Nuphar advena

spatterdock [Blooms: Jun-Sep]

Fragrant water lily flower stalks, like the leaves, develop directly from the rhizomes. Flowers are 3-6" across; they have four greenish-white sepals that rest on the water's surface; 15-40 brilliant white (occasionally pink) petals in multiple series; 35-120 stamens with bright yellow anthers distributed around the inner circumference of tthe flower; and a central stigmatic disc on the floor of the flower at the base of the stamens. Flowers open and close daily. The fruit is 1-2" long and globoid; its stalk bends downward so the fruit develops underwater. After the tiny seeds (~1/16-1/8") are released, they float for some time, dispersed by wind and water currents, then sink to the bottom of the water body where they germinate.

Nymphaea

Nymphaea odorata

fragrant water-lily [Blooms: May-Aug]

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]

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]

Eastern prickly pear is the commonest of three prickly pears native to Illinois, all quite rare. Eastern prickly pear can grow to be as much as 2' tall but Jackson Park specimens rarely exceed 6". Flowers are 2-3" across consisting of numerous yellow, satiny tepals, the innermost layer with reddish-orange highlights towards the tepals bases, 50-1500 stamens with pale yellow anthers, and a single style topped with a ring of six fleshy, white stigmas. Each flower lasts a single day. Fruits are initially green but turn reddish-brown when mature; they are 1-2" long, less than 1" in diameter, and concave on the top.

Opuntia

Opuntia humifusa

Eastern prickly-pear [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]

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]