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Giant St. John's wort stems and branches terminate in clusters (cymes) of 1-5 flowers 2-2.5" across; the central bud opens first. Giant St. John's wort has the largest flower of all the St. John's worts found in Illinois. Each flower has five green sepals 1/3 the length of the petals; five bright yellow, often twisted, petals; more than 100 yellow stamens with yellow anthers; and a yellow-green pistil with five distinct styles fused at their bases, each with red stigmas at their tip. Five carpels are present in the flask-shaped ovary. The fruit is a five-chambered, bullet-shaped structure up to 1.25" long and 1/2" wide, initially green, turning brownish-black with maturity; the capsule is topped with the remnants of the (five) styles and contains numerous lozenge-shaped, 1 mm long, black seeds. (When fully mature and with appropriate magnification, the seeds look like ears of corn.) Note in particular the very large (2") flowers and the five styles on the pistil of giant St. John's wort — most other Hypericum spp. have either one or three styles. Kalm's St. John's wort also has five styles, but that is a much smaller and woody plant with narrower leaves and much smaller flowers.

Hypericum

Hypericum ascyron

giant St. John's wort [Blooms: Jun-Aug]

Kalm's St. John's wort is a 1-3 ' tall shrub, largely restricted to the Great Lakes basin of the U.S. and Canada; it is formally listed as "critically endangered" in Illinois (but is quite common in Jackson Park). The flowers occur in clusters (corymbs) of 3-7. Individual flowers are 1-1.25" across; they have five light green, lance-shaped sepals half the length of the petals, five spreading golden-yellow petals, 150-200 stamens with yellow anthers, and a five-lobed yellow ovary with five (partially or completely fused) styles. The ovary often is markedly five-lobed. The fruit is a teardrop-shaped capsule resting on the five widely-spread sepals containing five (occasionally four) carpels; the capsules are initially green, then turn bright red, then finally brown as the numerous black, oblong seeds mature. Woody lower branches and the strongly five-lobed pistil and fruit are distinguishing characters that separate this species from other Jackson Park St. John's worts.

Hypericum

Hypericum kalmianum

Kalm's St. John's wort [Blooms: Jun-Aug]

Common St. John's wort flowers are ~3/4" across, with five green sepals, five oblong yellow petals, three widely-spreading styles (and three carpels) with scarlet stigmas on top of a globular yellow ovary, and numerous (45-85) stamens with yellow anthers. The filaments of the stamens fuse into three groups near their bases. Unique among the St. John's worts in Illinois, common St. John's wort has petals with tiny black dots (glands full of essential oils) that are restricted to the petal margins. (Hypericum punctatum, spotted St. John's Wort, also has black dots on the petals but, in that species, they extend to the interior of the petals.) These black glands may also occur sparsely on the anthers. The fruit is a three-chambered, bullet-shaped structure 1/4" long, initially green, turning reddish-brown with maturity; the capsule is topped with the remnants of the (3) styles and contains numerous seeds. Common St. John's wort contains chemicals that may interact adversely with a number of common pharmaceuticals despite its widespread use in traditional medicine and may be toxic to livestock in large doses.

Hypericum

Hypericum perforatum

common St. John's wort [Blooms: Jun-Aug]

Shrubby St. John's wort is, as the name says, "shrubby;" the "prolificum" part refers to the exceptionally numerous stamens. The upper stems and axils of the two upper pairs of leaves produce clusters of 3-7 flowers. Flowers are ~1" across, with five green sepals much shorter than the petals, five yellow petals, 150-500 stamens, and a pistil with three styles united at the base and appressed along their lengths. The fruit is a capsule <1/2" long, cone shaped and tapering to the tip, with the tips of the three styles persistant, not lobed but bluntly triangular with three compartments internally (corresponding to the three carpels of the ovary). Hypericum prolificum and Hypericum kalmianum both have woody lower branches (the only Hypericum sp. that do) and are very similar vegetatively, but H. kalmianum produces a seed capsule with the remnants of five styles and has five internal compartments while H. prolificum produces seed capsules bearing the remnants of three styles and has three internal compartments.

Hypericum

Hypericum prolificum

shrubby St. John's wort [Blooms: Jun-Aug]

Round-fruited St. John's wort flowers are 1/2-3/4" across, with five (sometimes four) green sepals shorter than the petals, five rounded, bright-yellow petals with curled margins and tips, 45-85 yellow stamens with orange anthers, and a slender, flask-shaped pistil with three styles fused at their bases bearing tiny stigmas. The fruit is globular with a long, tapering neck, not a lobed bullet-shape as in other Hypericum. Descriptions of this species say it has three styles, but the populations in Jackson Park typically have flowers with what is apparently single style but close inspection (especially of older flowers) show actually has three styles, closely appressed. The styles separate at their tips late in blooming or early in the development of most fruits.

Hypericum

Hypericum sphaerocarpum

round-fruited St. John's wort [Blooms: Jun-Jul]

Yellow iris might be mistaken for simply a yellow variant of blue flag iris, but the two species are distinct. Yellow iris has basal leaves longer (3-4') than the flower stalk; both prefer wetlands and shallow water. The leaf venation is parallel, typical for a monocot. As you would expect, the flowers are yellow with golden patches. Each flower stalk bears branches that terminate in clusters of 2-3 flowers. Each flower is 3-4" across and consists of: (1) three yellow sepals (the "falls") drooping towards their ends with a conspicuous golden spot (the "signal") whose edge is outlined by a series of brown to maroon spots or lines; (2) directly above the sepals are three yellow petal-like style branches (the "style arms") with upturned tips (the "style crests") (the stigma, where pollen is captured, is located at the fold between the style arms and crests); and, (3) between the sepals are three very short yellow petals (the "standards") that barely rise up above the plane of the sepals and style branches. The stamens are located under the style arms. The seed capsules are three-lobed, elongate (3") ovals that contain seeds that float on the water when released. Yellow iris is an introduced plant from Europe, now naturalized.

Iris

Iris pseudacorus

yellow iris [Blooms: May-Jun]

Black walnut has separate male and female flowers on the same tree (often the same branch). The male florets occur on 3-6" long, dangling, green, cylindrical catkins that arise from the leaf axils of one-year-old branchlets; the florets are 1/8" across and are comprised of a short, tubular calyx with 2-6 lobes and 15-40 stamens with greenish-yellow or purplish anthers. The female florets occur in groups of 2-5 on short spikes that arise from the tips of the current year's new branchlets; these florets are also about 1/8" across but are comprised of a short, tubular calyx with four lobes, a stout, green ovary covered with sticky hairs, and a pair of stout, bushy styles with red-tinged stigmas. The female florets are wind pollinated; the trees are self-fertile if cross-pollination does not occur. Fertilized female florets develop into globoid nuts about 2.5" long and 2" across that initially retain the styles; the nuts are solitary or in pairs. The thick husk turns from green to yellowish-brown to black as the fruit matures. The nuts cannot germinate unless they are exposed to 90-120 days of cold winter temperatures.

Juglans

Juglans nigra

black walnut [Blooms: May?-Jun]

Torrey's rush is 2-3' tall, with robust stems that are deep green, hairless, and circular in cross section; each stem bears 2-5 alternate leaves and 1-3 basal leaves. The central stem branches rapidly at its tip; each branch ends in a spherical flowerhead about 1/2-3/4" across. The lowest flowerhead in the array sits above a very long, thin bract (main image). There may be up to 23 flowerheads in the array. Individual flowerheads are composed of 25-100 florets that each have six stamens, a narrow ellipsoid ovary with a 3-part stigma (center of insert), and six tepals (sepals and petals) in two layers; all tepals are green, bract-like, lance-shaped, and 3-6 mm long. The flowerheads are more bristly than flower-like in appearance. The flowers are wind-pollinated. After fertilization, flowerheads turn brown and look very spikey.

Juncus

Juncus torreyi

Torrey's rush [Blooms: Jul-Aug]

Kochia's greenish-yellow flowers are 4-5 mm across. Perfect flowers have five green, bluntly-triangular sepals that develop wings along their outer face, no petals, five stamens each with two large yellow or pink anthers, and a divided style; pistillate flowers lack the stamens. The flowers are wind-pollinated. The fruit is a flattened, five-lobed, winged capsule nestled in the sepals that contains a solitary seed. ITIS says that the accepted name for this plant is Kochia scoparia; World Flora Online claims the proper binomial is Bassia scoparia.

Kochia

Kochia scoparia

kochia [Blooms: Jul-Aug]

Two-flowered cynthia is a yellowish-orange dandelion-like composite flower consisting of only ray florets. Each of the 25-60 ray florets is elongate with a truncated tip with five tiny teeth; the stamens are orange and the styles have bifurcated tips. The basal leaves are hairless, up to 7" long and 2" across, with a broad, rounded tip; the base of the leaf narrows into winged petioles that clasp the stem. The margins of the leaves are nearly toothless. The 1-2' tall stems arise from the center of the basal rosette. One to six 1" wide flowers sit on stalks that emerge from an upper stem leaf axil where one or two lance-shaped leaves clasp the stem; unusually, only two flowers are open at any one time. The yellow-orange color is distinctive; most other dandelion-like flowers are yellow.

Krigia

Krigia biflora

two-flowered cynthia [Blooms: Jun-?]

Canada lettuce gets up to 8' tall (and is quite impressive when it does), but is usually considerably shorter. On larger plants, the inflorescence is an apical pyramid 2' tall covered with dandelion-like flowerheads; on smaller plants the flowerheads may be more scattered. Flowerheads are yellow or "dirty orange," a bit over 1/4" wide with a 1/2" long calyx and 15-22 ray florets with toothed tips, each with five stamens and a bifurcated style; there are no disc florets. Seeds are oval, flattened, and attached to a tuft of threads (like a dandelion). Small Canada lettuce plants are superficially similar to prickly lettuce (Latuca serriola), but the latter has large spines on the underside of the main veins of the leaves and seeds that are attached to the tuft of hairs by a beak twice as long as the seed.

Lactuca

Lactuca canadensis

Canada lettuce [Blooms: Jul-Sep]

Prickly lettuce flowerheads dandelion-like, a distinctive pale lemon-yellow color, and 1/4-1/2" across; there are about 20 ray florets with squared, serrated ends (with five teeth), five stamens with yellow anthers, and a bifurcated style whose base is surrounded by the anthers. The seeds are attached to the tuft of hairs by a beak up to twice as long as the seed. Prickly lettuce is superficially similar to Canada lettuce (Latuca canadensis), but the latter has no spines on the leaves and seeds that are attached to a tuft of hairs by a beak no longer than the seed. Prickly lettuce is the closest wild relative to domestic lettuce (L. sativa).

Lactuca

Lactuca serriola

prickly lettuce [Blooms: Jul-Sep]

Butter-and-eggs (aka, toadflax) is an exotic, native to Europe and Asia. The stem is 1-2' tall, usually unbranched, terminating in an elongate (3-6" long) flower spike. The 1" long, yellow and orange, snapdragon-like flowers with a long nectar spur are distinctive. The vertically-oriented, tubular corolla has an upper and lower lip, each divided into two lobes that curve away from the axis of the flower. There are four fertile stamens of two distinct lengths hidden inside the corolla and a single style. The flowers are mostly pollinated by bumblebees, which are strong enough to push their way into the flower and have a long enough tongue to access the nectar.

Linaria

Linaria vulgaris

butter-and-eggs [Blooms: Jul-Oct]

Spicebush is a highly branched, woody shrub that reaches heights of 5-15'. It blooms very early in the spring — March and April in Jackson Park, before most plants have leafed out — so it is one of the few spots of color in a grey landscape. When spicebush blooms, leaves are not yet present; the small clusters of yellow flowers have the stage all to themselves. Some specimens have only a single sex of flower (pistillate or staminate); less commonly, spicebush plants may bear "perfect" flowers with both functional male (stamens) and female (pistils) organs. Individual flowers are about 1/4" across, pastel-yellow, with six yellow, petal-like tepals. Male flowers have nine stamens in three groups of three, each group associated with a two-lipped, yellow nectary; The anthers are bright yellow. Female flowers have an ovary with a single pistil and 6-18 non-functional pseudo-stamens; the stigma is large, bright white, and rough-surfaced. The flowers are said to have "an unusually sweet fragrance." The fruit is a fleshy drupe with a single stone; it turns bright red in the late summer/early fall.

Lindera

Lindera benzoin

spicebush [Blooms: Mar-Apr]

Tulip trees are the tallest native hardwood — one living specimen is 190' tall, the tallest tree east of the Mississippi. (Most tulip trees are in the 80-100' range). Illinois is on the western edge of tulip trees' range, but it is the state tree of Indiana (and Tennessee). Tulip trees have a single trunk and (usually) a pyramidal crown; the bark is gray with whitish furrows. Flowers arise on short stalks in leaf axils. Each flower is bell-shaped, erect, 2-3" across, and ~2.5" tall; there are 9 tepals — 3 pale green sepal-like tepals reflected downward and 6 fleshy petal-like tepals, yellowish-green to green in their upper half with an broad orange stripe below; the very base of the petal is pale yellow-green. In the middle of the flower is a tall (2.5") conical cluster of 60-100 pistils (the receptacle); surrounding the receptacle are 20-50 white stamens with yellow anthers. The fruit is a 1.5" long winged seed (samara) reminiscent of an ash seed; the ovate seed lies at one end of a long, thin wing with a central ridge. The leaves alone are sufficient for a confident identification; in flower or in the fall when the receptacle has produced a crown-like circlet of woody, persistant basal samaras, tulip trees are unmistakable.

Liriodendron

Liriodendron tulipifera

tulip tree [Blooms: June]

Hairy puccoon flowers are 3/4" across with a VERY hairy, green calyx with five sharply-triangular teeth , a yellow to yellow-orange tubular corolla with five widely-spreading rounded lobes, five stamens hidden inside the corolla beneath the throat, and a single style with a two-lobed, disc-like stigma. The flowers of hairy puccoon are heterostylous; i.e., either they have long stamens (~14 mm) and a short style (2-5 mm) or short stamens (~3 mm) with a long style (5-12 mm), but neither the anthers nor the stigma extend beyond the throat of the corolla (although they may get close). Hairy puccoon is very similar to hoary puccoon (L. canescens) but with stems that are less hairy and the hairs are "disorganized." The calyx at the base of the floral tube are very hairy in both species, but the teeth of the calyx in L. caroliniense have a distinct keel running down their midline. (I.e., subspecies L. caroliniense croceum.) Flowers of hairy puccoon are larger — up to 1" vs. 1/2" in hoary puccoon. The fruit is an egg-shaped nutlet, white when mature.

Lithospermum

Lithospermum caroliniense

hairy puccoon [Blooms: May-Jun]

In grape honeysuckle, a short flowering stalk emerges from the tip of the stem where it emerges from the terminal pair of leaves; 2-5 whorls of flowers develop along this flowering stalk. Each flower is about 1" long. It consists of an egg-shaped, swollen, dark green ovary; a pale yellow to orange-yellow, two-lipped corolla that fades with age to orange or red; five stamens with yellow anthers; and a single style with a dome-shaped stigma. There are no hairs on the flowers. Both the stamens and the style protrude from the corolla. The ovary of fertilized flowers produces berries which are initially green but, at maturity, become globoid, orange-red to red, and about 1/4-1/2" long. Grape honeysuckle is the only honeysuckle (native or exotic) in Jackson Park that is a woody vine; it is distinctive and should be easy to recognize.

Lonicera

Lonicera reticulata

grape honeysuckle [Blooms: Jun]

Bird's-foot trefoil produces whorls of 3-8 flowers on the end of long stalks that arise from leaf axils. Individual flowers are bright yellow (sometimes tinted with orange), about 1/2-3/4" long and across, in the standard pea-like pattern — a single vertical petal (the standard), a pair of lateral petals (the wings) and two petals perpendicular to the standard fused for about half their length (the keel). The calyx has long, light-green teeth. There are 10 stamens (of two lengths, alternating) and a single curved style, hairy at the tip. The fruit is an 1" long, purplish-brown, pea-like pod containing about two dozen seeds with the calyx at one end and a long "beak" (the remnant of the pistil) at the other.

Lotus

Lotus corniculatus

bird's-foot trefoil [Blooms: Jun-Sep]