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Dandelion plants produce one to several slender flowering stalks from the center of the basal leaf rosette. Each floral stalk is cylindrical, hollow, and light green (often with a light reddish green base); there is a single 1-2" wide, yellow flowerhead at the apex of each stalk. The floral stalk may be covered with cobwebby hairs. Each flowerhead has 150-200 yellow ray florets spreading outward toward the periphery of the flowerhead; disc florets are absent. The ray flowers have a flat, strap-like "petal" with a series of tiny teeth at its distal end; the anthers sheath the surface of the style, which protrudes from the distal end of the tube of fused anthers as a bifurcated stigma. The base of the flowerhead is covered by two layers of green bracts; the inner layer of bracts forms a cylindrical tube around the ovaries of the ray florets, while the outer layer of bracts is sharply reflexed back along the floral stalk. The fruit is a narrow, cylindrical seed 3-4 mm long with 5-10 longitudinal ribs on its surface; the seed is attached by a 7-9 mm long beak (stalk) to a parachute-like tuft of white hairs. The airy seedheads are formally known as "clocks" in both British and American English (before the seeds are released by an errant breeze or child). Dandelion seeds can remain viable in the soil for up to nine years.

Taraxacum

Taraxacum officinale

dandelion [Blooms: Mar-Jun]

The tips of the stems of goat's-rue give rise to 2-3" long racemes of buds and flowers. The unmistakable, bicolored pea-like flowers are about 1/2-3/4" wide and long, creamy white or yellowish on the vertical petal (the "standard") and rosy-pink on the lateral wings and the keel. (A total of five petals.) The flowers consist of a short, tubular calyx with five teeth, five petals in a pea-like configuration, 10 stamens (nine with fused filaments, one free from its midpoint) with small yellow anthers, and a single pistil with a tiny terminal stigma. Both stamens and pistil are enclosed by the keel. The seedpods are 1.5-3" long, cylindrical, slightly flattened beans spreading laterally from the flower spike; these, too, are (densely) silky-hairy. The seedpods are initially light green but turn brown with maturity. They split along the symmetry plane of the seedpod and the valves develop a spiral curl to release the seeds. Goat's-rue prefers sandy habitats. The long, woody roots contain rotenone, a compound that is toxic to fish and insects; it inhibits ATP production and disrupts mitochondrial function by blocking the electron transport chain. It would not be a good idea to suck on or ingest the roots of goat's-rue.

Tephrosia

Tephrosia virginiana

goat's-rue [Blooms: Jun-Jul]

Purple meadow-rue is a native perennial that is listed as "vulnerable" in Illinois. The species is found in most of the lower 48 states in the U.S. but is notably absent from states on the Atlantic and Pacific coasts (however, it is present along the Gulf of Mexico). Purple meadow-rue is dioecious — some plants produce only staminate (male) flowers, each with around a dozen stamens; other plants bear only pistillate (female) flowers, each with about ten pistils. The male flowers are the showier of the two. Petals are absent (the plant is wind-pollinated). Both the narrow, whitish-grey, thread-like pistils and the yellow-green stamens (with pale yellow anthers) droop from 4-5 light green sepals (that may drop off). Fertilized female flowers develop a single, spindle-shaped fruit that is 1/4" long, elongated, sharply pointed with a remnant style, 4-6 raised ribs, and slightly concave along one side. The fruit is initially green, turning brown with maturity. Early meadow-rue (Thalictrum dioicum) is similar to purple meadow-rue but has light purplish-green stems and leaves with 3-9 (typically five) rounded lobes and long petioles on the upper leaves.

Thalictrum

Thalictrum dasycarpum

purple meadow-rue [Blooms: May-Jun]

Early meadow-rue's main stem terminates in a panicle up to a foot long and wide; each branch in the panicle has a corymb of about five flowers at its tip. Early meadow-rue is dioecious — some plants produce only staminate (male) flowers, each with 10+ stamens; other plants bear only pistillate (female) flowers, each with up to 15 pistils. Both male and female flowers droop from their stems, but the male flowers have a longer droop than do the female flowers. Both male and female flowers are about 1/2" long and 1/4" across with 4-5 pale green sepals with white margins (which often fall off). Neither male nor female flowers have petals; pollination is via the wind. Fertilized female flowers produce ellipsoid, dry seeds that are pointed at both ends; the surface bears strong ribbing. Early meadow-rue prefers shady woodlands. It has more lobes on its leaves (usually 3-5), and the lobes are more rounded than purple meadow-rue (Thalictrum dasycarpum), the other Thalictrum species in Jackson Park, does (2-3 pointed lobes).

Thalictrum

Thalictrum dioicum

early meadow-rue [Blooms: Apr-May]

Field pennycress's central stem and the upper side stems produce racemes of flowers at their tips. The flowers bloom at the tip of the raceme, which continues to elongate to 3-8" long and to produce new buds; the prominent, disk-shaped fruits develop lower on the raceme. Individual flowers are about 1/8-1/4" across on a 1/2" pedicel; there are four green sepals with whitish edges, four white, oval petals, six yellowish-green stamens (three on each side of the flattened ovary), and a single short style. The fruit is a 1/2" wide flattened, winged disc with a distinct U-shaped notch at the apex; the fruits are borne on the flower pedicels, which spread perpendicular to the stem. Each seedpod has two compartments, each compartment containing several dark brown seeds. Other mustards have long, cylindrical seedpods; the nearly-circular seedpod of field pennycress is unique among Jackson Park mustards. Young field pennycress plants are edible but become very bitter at flowering. Cows that feed on field pennycress produce "tainted" milk that tastes like garlic.

Thlaspi

Thlaspi arvense

field pennycress [Blooms: Apr-Jun]

Erect hedge-parsley's main stem and side stems give rise to umbels 1.5-2" across of 10-20 umbellets of flowers. Each flower is about 1/8" across consisting of five white petals (often markedly unequal in size), and a creamy white center surrounded by five pink to white stamens. The fruit is an 1/8" long oval covered in hooked hairs to aid in bur-like dispersal; it contains two seeds. (The fruit of common hedge-parsley (Torilis arvensis) has straight or only slightly curved hairs, not hooked, but the hairs are barbed.)

Torilis

Torilis japonica

erect hedge-parsley [Blooms: Jun-Jul]

Ohio spiderwort's flowers and buds occur in a cluster, each cluster on a hairless flower stalk (pedicel) with a pair of long, leaf-like bracts at its base at the apex of the plant. Individual flowers are about 1-1.5" across, with three green, oval sepals offset from the petals; three rounded blue-violet petals; six stamens with blue filaments and bright yellow anthers; a single blue style with a small white stigma; and fine, thread-like, violet hairs radiating out from the stamen and style bases in the center of the flower. The seed capsules are 4-8 mm long, ovoid, with three distinct compartments. The mature seed capsule splits into three sections, each releasing 3-6 oblong, strongly ribbed, brown seeds. The flowers open early in the morning but close in the afternoon (later on cloudy days). Ohio spiderwort is the commonest spiderwort in Illinois and the only Tradescantia species to occur in Jackson Park; the very similar Virginia spiderwort (Tradescantia virginiana) can be distinguished from Ohio spiderwort by its hairy flower stalks (pedicels).

Tradescantia

Tradescantia ohiensis

Ohio spiderwort [Blooms: Apr-Sep]

Western goat's-beard's stems terminate in a single flowerhead, with the stem strongly swollen beneath the flowerhead. Individual flowerheads are pale lemon yellow and about 2" across. Between 50-180 ray florets are present; disc florets are absent. A series of about 13 sharply pointed, narrow bluish-green bracts (significantly longer than the outer ray florets) surround the base of the flowerhead. The outer ray florets (the "petals") are much longer than the inner ray florets. All ray florets have an outer tip of the "petal" decorated with five small teeth. Near the base of the ray florets is a composite reproductive structure consisting of a single style, bifurcated at its tip, and five stamens with black anthers closely appressed to the middle of the style. The flowerheads open in the morning but close in the afternoon; the flowerheads sometimes track the sun like a sunflower. Fertilized florets produce a long, narrow, naked seed densely covered with small teeth; the seed is attached to a plume of fine white hairs (like a dandelion). The seed head looks like a giant version of a dandelion seed head. Western goat's beard is very similar to yellow goat's beard (Tragopogon pratensis) but prefers drier habitats; the latter has only eight bracts (rather than 13) surrounding the flowerhead and the bracts are the same length (not longer) than the outer ray florets.

Tragopogon

Tragopogon dubius

western goat's-beard [Blooms: May-Sep]

Yellow goat's-beard stems produce a long naked stalk from their tips that bears a single flowerhead. Individual flowerheads are bright yellow and 1-2.5" across. Between 50-180 ray florets are present; disc florets are absent. A series of about eight sharply pointed, narrow green bracts (the same length or shorter than the outer ray florets) surround the base of the flowerhead. The outer ray florets (the "petals") are much longer than the inner ray florets. All ray florets have an outer tip decorated with five small teeth. Near the base of the ray florets is a composite reproductive structure consisting of a single yellow style, bifurcated at its tip, and five stamens with black anthers closely appressed to the middle of the style. Fertilized florets produce a long, narrow naked seed; the seed is attached to a plume of fine white hairs (like a dandelion). The seed head looks like a giant (3" across) version of a dandelion seed head. Like Tragopogon dubius, it's an exotic, but at least it's less aggressive. Distinguish yellow goat's beard (T. pratensis) from western goat's beard (T. dubius) by flower color (bright yellow vs. pale yellow), foliage color (green vs. bluish green, number of floral bracts (8 vs. 13), leaf shape (tips curled vs. tips straight), and length of the floral bracts (same as petals vs. much longer than petals).

Tragopogon

Tragopogon pratensis

yellow goat's-beard [Blooms: May-Aug]

Fuzzy flower stalks about 1" long arise from the leaf axils of low hop clover. The flowerheads are roughly spherical, lemon yellow, and about 1/2" across comprised of 20-40 pea-like florets with five petals; each floret is about 4 mm long. The upper petal (the standard) on each floret is conspicuously grooved and forms a hood over the two petals forming the keel; two lateral petals flank the keel. Fertilized florets form tiny seedpods that are shorter than the keel. The flower color and foliage of low hop clover are very similar to black medic (Medicago lupulina), but the standard on black medic is not grooved and sits perpendicular to the keel.

Trifolium

Trifolium campestre

low hop clover [Blooms: May-Aug]

Alsike clover is an exotic perennial native to Europe. Despite the scientific name ("hybridus"), it is not a hybrid. (Linnaeus thought it was a hybrid of red and white clover. It isn't.) The plant is 6-24" tall, with occasional branches along the stems. One- to three-inch-long flower stalks arising from the leaf axils terminate in a flowerhead 1/2-3/4" across; florets tend to be white on the top of the flowerhead and reddish-purple to pink on the bottom, but may all be reddish. Individual florets are 1/4" long with five petals in a pea-like bloom. They have a sharply pointed standard (the major vertical petal, perpendicular to the keel), two petals that make up the keel, and two lateral petals that flank the keel. Ten stamens and a single pistil are hidden inside the keel. Unlike red clover (T. pratense) and white clover (T. repens), there are no pale chevron-shaped markings on the leaflets.

Trifolium

Trifolium hybridum

alsike clover [Blooms: May-Jul]

The upper stems of red clover end in 3/4-1" wide pinkish-purple (not actually red) flowerheads, usually with 1-3 leaflets or a compound leaf and some pointed bracts immediately below the bloom. The florets are tubular modification of a typical pea-like flower with five petals; the upper petal (the standard) is slightly longer than the other four petals and has a slightly pointed tip. Red clover is easily identified by the pinkish-purple flowerheads, the leaflets inserted just below the flowerheads, and the white chevrons on the leaflets.

Trifolium

Trifolium pratense

red clover [Blooms: Apr-Jun]

White clover's hairless, leafless flower stalks are up to 3" long. They emerge directly from the horizontal stems and grow perpendicular to the ground, producing a single globular 3/4" wide flowerhead at their tips. The flowerheads are all white, consisting of 20-50 pea-like florets. The florets are tubular, consisting of a green calyx with five long, narrow teeth, and five white or pinkish-white petals (a standard, two petals making the keel, and a pair of lateral petals flanking the keel). White clover is similar to alsike clover (T. hybridum), but that species usually has some pink in the flowerheads and never has white chevrons on the leaflets.

Trifolium

Trifolium repens

white clover [Blooms: May-Jun]

Each side stem of yellow bellwort produces a single, elongate bell-shaped flower at its tip. The flowers droop on their stem-like pedicels (about 1 " long) such that they open downwards and are often partially hidden by the leaves. Each flower is 1-2" long and consists of six yellow tepals twisted along their length (often with greenish bases), six white stamens with elongated yellow anthers, and a pistil with a three-lobed stigma. The fruit is a three-section capsule that looks (vaguely) like three fat triangles with oval bases, stuck base to base to base. Seeds are freed when the capsule splits. Seed dispersal is added by the attraction of ants to a fleshy, nutrient-rich appendage (an elaiosome) on the seed; the ants carry the seed back to their nest where they eat the elaiosome and abandon the seed.

Uvularia

Uvularia grandiflora

yellow bellwort [Blooms: Apr-May]

Clusters of lowbush blueberry's flowers develop on the previous year's twigs. The flowers are about 1/4" long, urn- or bell-shaped, nodding, white, and waxy. The flowers contain a short, green calyx with five teeth; a short, tubular corolla that is pinkish white or white with five triangular, recurved lobes around its margin; ten stamens with reddish brown anthers recessed behind the margin of the corolla and clustered around the style; and a single style whose stigma extends right to the margin of the corolla. Fertilized flowers are replaced by approximately 8 mm diameter berries, initially green but turning dark blue with a whitish bloom as they mature. (I.e., they look — and taste — like blueberries.)

Vaccinium

Vaccinium angustifolium

lowbush blueberry [Blooms: May]

The apex of the common mullein plant is a club-shaped flower spike 6-24" long, covered with scattered light-yellow flowers each 3/4" across. Individual flowers have five hairy, green sepals; five pale yellow petals (the lower two slightly larger than the upper three); five stamens with reddish-orange anthers; and a single green style with a heart- or disc-shaped stigma. The upper three stamens are shorter than the other two stamens and covered with white or yellow hairs; the lower two stamens are longer and largely hairless. The fruit is an oval, two-celled seed capsule, brown when mature, each cell filled with numerous (25-150) tiny orange to brown seeds. Common mullein is immediately recognizable and impossible to confuse with any other local plant.

Verbascum

Verbascum thapsus

common mullein [Blooms: Jun-Aug]

The top of the wingstem plant is a dome (a panicle) of coarse-looking flowerheads. Each flowerhead is 1-2" across, with 2-10 yellow, oblong, drooping petals, 1/2-1" long that are derived from the sterile ray florets. Some 40-60+ yellowish-green, tubular disk florets project in all directions in a hemisphere of widely-spaced, robust, bud-like blunt cylinders, the tips of the disk florets. When receptive to pollen, the disk florets bear a protruding style with a bifurcated, curling pair of stigmas (likened by one source to a "pince-nez" — a pair of eyeglasses on a handle); the five stamens and their flattened, black anthers are appressed to the body of the style. The fruit is a teardrop-shaped seed with a pair of thin wings and two short, robust, spiky awns. Immature seeds are green; the seeds (and seedheads) turn brown when mature.

Verbesina

Verbesina alternifolia

wingstem [Blooms: Jul-Oct]

The tip of a smooth ironweed central stem bears a cluster (a corymb) up to 4" in diameter of magenta composite flowerheads that is quite densely packed in a flat or (sometimes) domed inflorescence. The branches of the inflorescence (but not the stem) may be lightly fuzzy with small hairs. Each flowerhead is 3/4" across and contains 10-30 magenta disk florets, each with five lobes and a very prominent, divided style with curled tips (the stigmas) and five stamens appressed to the base of the style; ray florets are completely absent. The bracts that cover the underside of the flowerheads are green or purplish brown, flattened, appressed, and rounded at their tips, imbricated like fish scales with white, cobwebby hairs around their edges. The fruit is a naked seed with an attached tuft of white hairs (actually, scales). To sort out the Jackson Park ironweeds: (1) if both leaves and stem are densely covered with fine white hairs, the leaves are about 3-4 times longer than wide, and each flowerhead has more than 30 disk florets, it's Missouri ironweed (V. missurica). (2) If both leaves and stems are hairless, there are less than 30 disk florets, and the leaves are narrow (typically a half inch or less; about 6-10+ times longer than wide), it's smooth ironweed (V. fasiculata). (3) If the stems and leaves have only short hairs, there are less than 30 disk florets, and the leaves are about 2" wide and 4-6 times longer than wide, it's tall ironweed (V. gigantea).

Vernonia

Vernonia fasciculata

smooth ironweed [Blooms: Jun-Sep]