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The upper stems of hairy aster give rise to 2 foot long, 1.25 foot wide panicles with a central rachis that produces spreading or ascending primary branches and smaller secondary branches that bear the flowerheads. Each flowerhead is 1/2-3/4" across with 15-35 white ray florets and 20-40 yellow disk florets that turn reddish purple or brown with age. The bracts (phyllaries) that surround the base of the flowerhead are present in 4-5 layers; they are 3 mm long and light green with a long, darker green tip. The edges of the phyllaries are often rolled under and thus may appear needle-like. The phyllaries and the bracts attached to the panicle branches both have a tiny spine at their tip. (Note: heath aster (S. ericoides) also has such spines but has smaller flowerheads, broad, blunt phyllaries with a larger spine, and the hairs on the stems are either appressed to the stem or are ascending.) The fruits are 1-1.15 mm long, tan colored, dry seeds with 3-4 longitudinal ribs and a tuft of white hairs. After blooming is completed, rosettes of 3" long, 1" wide, spoon-shaped basal leaves develop and persist through the winter into the spring, but wither away before blooming begins again.

Symphyotrichum

Symphyotrichum pilosum

hairy aster [Blooms: Aug – Nov]

The panicles of Short's aster's flowerheads are up to 18" long and 8" across; the panicles arise from the tips of the central stem and the upper lateral branches. The flowering branches are long, widely spreading or arching, and covered with small, leaf-like bracts and stiff hairs. Individual flowerheads are 3/4-1" across. Flowerheads consist of 10-20 lavender or pale blue-violet (rarely white) ray florets and 15-23 disk florets, initially yellow but becoming reddish purple over time. The phyllaries that surround the base of the flowerheads are covered with stiff, white appressed hairs, are whitish or light green with a diagnostic dark green, diamond-shaped tip, and sometimes also with a dark green medial vein. The fruits are 2-3 mm long, oblong-shaped, with a tuft of light brown hairs at one end. The indented bases of the lower and middle leaves, the slender, wingless petiole, the hairless leaves, and the phyllaries with dark green apical diamonds together are good indicators of Short's aster. Short's aster is the commonest aster in bloom in Jackson Park in early autumn; later in the autumn it is overtaken in numbers (or at least visual impact) by New England asters.

Symphyotrichum

Symphyotrichum shortii

Short's aster [Blooms: Aug – Nov]

The upper stems and branches (some arising from upper leaf axils) of white arrowleaf aster terminate in 6-18" long panicles of flowerheads; the panicles are 2-3 times longer than wide. Each flowerhead is 1/2-3/4" across with 8-15 pistillate, white (rarely pale lavender) ray florets and 10-15 perfect (both stamens and styles present) disk florets. The disc florets are initially yellow but turn pink or light purple with age such that the flowerheads with yellow disk florets are often in the minority on the plant. The individual disk florets strike me as being larger than on many asters. The phyllaries (bracts) covering the base of the flowerhead are narrowly lance-shaped, usually hairless, dark green in the middle tapering to narrow, stiff, green to purplish tips. The fruits are 2 mm long, purplish-brown dry seeds with longitudinal ribs and a tuft of hairs at one end. White arrowleaf aster is similar to Drummond's aster (Symphyotrichum drummondii) but is less hairy and has distinctly different phyllaries. Among asters with white flowerheads, only white arrowleaf aster has heart-shaped leaves. (Other asters with heart-shaped leaves typically have blue to violet flowers.)

Symphyotrichum

Symphyotrichum urophyllum

white arrowleaf aster [Blooms: Aug/Sep – ?]

The inflorescences of common comfrey are nodding cymes or racemes of flowers that arise from the tips of the stems and the lateral branches. The flowers are bell-shaped, about 1/4" across and 1/2-5/8" long. Each flower has a hairy, green calyx with five lance-like teeth that is half the length of the corolla; a purple, pink or white funnel- or bell-shaped corolla with five small, recurved lobes at its lip; five stamens that do not extend past the margin of the corolla; and a pistil with a single white style that barely protrudes past the corolla margin. The fruits are a cluster of four, 4-5 mm long, nutlets nestled in the remnants of the flower calyx; the nutlets are dark brown or black when mature, oval and slightly flattened at one end. The remnants of the style protrude from the center of the fruit. Extracts of common comfrey are sometimes sold as herbal remedies but be aware that the plant is mildly toxic; it contains pyrrolizidine alkaloids that can be absorbed through the skin or gastric system and may cause (potentially fatal) liver toxicity and may be carcinogenic. Comfrey products for internal use or for use on open wounds are banned in the U.S. by the F.D.A. Supplements containing common comfrey probably should be avoided.

Symphytum

Symphytum officinale

common comfrey [Blooms: Apr-Jul]

Japanese tree lilac (aka, Japanese lilac) is an exotic shrub or tree that is native to Asia; it gets 20-30 feet tall and 15-25 feet wide. It may have multiple trunks. The bark on the trunk is shiny and reddish-brown (rather like cherry trees) with horizontally elongated lenticels (air pores). The leaves are 2-5.5" long and 1-3" wide, opposite, dark green, oval with a sharp tip and a rounded base with a 1/2-1" petiole, pinnate venation, and smooth margins. The inflorescences are 6-12" high panicles dense with creamy-white flowers. Individual flowers have a 1-2 mm long calyx; a 3-5 mm long cream-colored corolla with five stubby lobes (petals) and a four-lobed apex; five white stamens with yellow anthers widely spreading radially; and a single long white style bearing a club-like stigma. The fruits are 3/4" long dry capsules, initially green but turning reddish-brown or yellow with maturity. The capsule splits to release the two winged seeds.

Syringa

Syringa reticulata

Japanese tree lilac [Blooms: Jun-Jul]

Some upper stems produce compound umbels at their tips made of tiny, yellow flowers; the umbels are very open (they remind me of a fireworks burst), up to 4-7" across with 12-15 umbellets of about a dozen flowers. Individual flowers are about 1/8" across with five tightly furled, yellow petals; five stamens emerging from between the incurled petals and widely spreading with pale yellow anthers; and two styles. Sepals are absent. The flowers tend to be either pistillate (stamens reduced or absent) or staminate (styles reduced or absent), but a few perfect flowers occur. Yellow pimpernel prefers dry habitats on a slope at the edge of woods.

Taenidia

Taenidia integerrima

Yellow pimpernel [Blooms: May-?]

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]

American germander flower spikes develop on the tips of the stems, with flowers opening from the bottom of the spike towards the (elongating) tip. Individual flowers are small (about 1/3-3/4"), white or lavender, with a bell-shaped, hairy calyx; an upper lip reduced to two lance-like, vertical lateral lobes that insure pollinators remain beneath the single long, arching single and 3-4 stamens with purple anthers; and a greatly expanded lower lip (a landing pad for pollinators) covered with purple spots. The fruit consists of four nutlets that are nearly fused together, nestled in the remnants of the calyx (which clearly shows the asymmetrical teeth — bottom two smaller than upper three). The nutlets are greenish white when immature, becoming redder and coarsely pitted as they mature. American germander is distinguished from other members of the mint family (Lamiaceae) by the very small upper lip and enlarged lower lip. Related species of Teucrium contain a toxic compound that causes liver damage in animals; for safety's sake, I would avoid herbal remedies that include American germander.

Teucrium

Teucrium canadense

American germander [Blooms: Jun-Aug]

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]

Immediately above the terminal stem leaves or leaflets of rue anemons is an umbel of one to six 1/2-1" flowers on 1.5" long pedicels. Each flower has 5-10 white or pinkish-white, petal-like sepals and a striking green center made of 1-16 pistils surrounded by 7-30 stamens with yellow anthers. There are no true petals. The fruit is a cluster of 5-15 strongly ribbed spindles about 8 mm long, pointed at both ends; each contains a single seed. Rue anemone prefers woodlands with dappled sunlight in the spring but tolerates shade in the summer months. The leaflets/leaves of rue anemone are similar to the leaflets of purple meadow-rue (Thalictrum dasycarpum), but you'll never confuse the two; purple meadow-rue blooms six weeks later and is seven feet taller than rue anemone.

Thalictrum

Thalictrum thalictroides

rue anemone [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]