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Downy sunflower is a very attractive sunflower which blooms in late summer. The composite flowers arise directly from the main stem. Each flowerhead is 2-4" across with 15-30 yellow ray florets and over 75 yellow disc florets in a 1" diameter central disk. Individual ray florets are sterile, the "petal" is about 1-1.5" long. Disc florets are about 1/4" long with five triangular lobes at the end of a tubular corolla; five stamens with white filaments (fused around the base of the style) and purple-brown anthers; and a single style, bifurcated at its tip, which protrudes above the stamens.

Helianthus

Helianthus mollis

downy sunflower [Blooms: Aug-Sep]

Western sunflower is a spindly plant that leads a double life. It is a perennial that first produces a very large (1.5' across) basal rosette of leaves; that basal rosette in turn produces a 2-4' tall, nearly leafless, stem. Clusters (a panicle) of 1-4+ flowerheads are present on pedicels less than 6" long emerging from the stem or upper leaf axils. The flowerheads are 1.5-2.5" across, with 8-20 ray florets, each bearing oblong yellow petals, and over 50 tubular, yellow disc florets with five lobes on their tips and five protruding brown anthers fused around a yellow style with a bifurcated stigma. Only the disc florets are fertile; the ray florets are sterile. (True throughout the genus Helianthus, although that seems more understandable (to me) than the situation in the genus Silphium, where the opposite is true.) Behind the flowerhead are 20-25 lance-shaped bracts (phyllaries) 5-7 mm long with pointed, green or straw-colored tips; there are often hairs round the margins of the phyllaries. The long, sparsely-leaved stem is diagnostic.

Helianthus

Helianthus occidentalis

western sunflower [Blooms: Aug-Sep]

Jerusalem artichoke should rightly be called a "sunflower" like the other four members of the genus Helianthus present in Jackson Park. Five to fifteen flowerheads ride on hairy peduncles up to 8" long and are 2.5-3.5" across; each is cupped by 2-3 overlapping series of phyllaries (bracts) that are more triangular than lance-shaped, hairy, and sharply pointed. The flowerheads consist of 10-20 sterile, yellow ray florets; the 60+ fertile disc florets consist of tubular yellow corollas about 1/4" long with five lobes at their apex and five protruding brown or black anthers fused around a yellow style with a bifurcated stigma. Jerusalem artichoke was cultivated by the indigenous peoples of the midwest for its tasty and carbohydrate-rich tubers.

Helianthus

Helianthus tuberosus

Jerusalem artichoke [Blooms: Aug – Oct]

Ox-eye sunflower (aka, false sunflower) flowerheads are 1.5-3.5" across with a prominant, gumdrop-shaped central disk; the plane of the flowerhead is horizontal, not vertical like most other (true) sunflowers. The 1.5-3" wide flowerheads consist of 10-18 yellow, tubular ray florets with yellow to golden-yellow, elongate-oval petals with notched tips and with two longitudinal folds in each petal; the numerous (10 to over 75) disc florets are yellow, tubular with five (brighter) yellow spreading apical lobes on the tubular corolla. Both disk florets and ray florets have a protruding, bifurcated style; the disc florets also have five stamens with brownish anthers which encircle the style below the paired stigmas. Behind the flower are two series of hairy bracts, the outer layer longer than the inner (a diagnostic character) and a velvety pedicel 1-8" long. Ox-eye sunflower is a "false sunflower" because both the ray and disc florets are fertile and can produce seeds; in true sunflowers, only the disc florets produce seed. The posture of the flower (horizontal rather than nodding towards the vertical) is also distinctive.

Heliopsis

Heliopsis helianthoides

ox-eye sunflower [Blooms: May-Jul]

American hops male and female flowers occur on separate plants. Actual female (pistillate) flowers occur in tight clusters ("aments") 3/4" long of 10-50 flower pairs on a stalk that arises from a leaf axil, each pair subtended by a bract; each flower has two long, thin styles. Male flowers have five pale green spreading sepals and five short, banana-shaped stamens. The fruit is a cone-like structure of overlapping bracts (originally present at the base of the female flowers) that surround the seeds; it is (obviously) found only on the female plants.

Humulus

Humulus lupulus

American hops [Blooms: Jul-Sep]

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]

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]

Fringed loosestrife is a native wildflower unrelated to the much-maligned (exotic) purple loosestrife. Flowers arise from the axils of the middle and upper leaves, held on slender, flexible pedicels up to 3" long so that the flowers commonly nod. Individual flowers are about 1" across; they have a green calyx with lance-shaped teeth behind a corolla with a reddish center and five yellow, petal-like lobes with a narrow yellow filament coming off the midline apex of most of the lobes. The five stamens have robust, tan-colored anthers and a simple white style with a tiny apical green stigma. The fruit is a shiny, green spherical capsule held cupped in the calyx. Fringed loosestrife prefers wet habitats near water or on moist hillsides.

Lysimachia

Lysimachia ciliata

fringed loosestrife [Blooms: Jun-Jul]

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]

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]

Lesser celadine flowers arise singly from the axils of the upper leaves or on the ends of stems. Individual flowers are about 1" across with three light green sepals half the length of the petals, 7-12 yellow, oblong petals, and a ring of about 30 (yellow) stamens around a central group of about 15-20 (greenish) pistils. This species rarely produces fruit, instead reproducing asexually. The alternative name "Ficaria verna" is occasionally used for lesser celadine, but that name is now considered invalid.

Ranunculus

Ranunculus ficaria

lesser celadine [Blooms: Apr-May]

In buckthorn, umbels of flowers arise from leaf axils. Flowers on a single plant may be perfect (both male and female organs present), but more commonly the flowers are dioecious with either all male (staminate) or all female (pistillate) flowers found on any given plant. Individual flowers are 1/4" across. They have four greenish-yellow, triangular, spreading sepals that together form a calyx and four petals that can't be easily seen without magnification; the "petals" in the flowers are actually sepals. Male flowers have four greenish stamens with cream-colored anthers; female flowers have a single style that has a tip divided into four branches. After fertilization, female (or perfect) flowers produce a shiny black, 1/4" wide, cherry-like fruit containing 3-4 seeds. Birds can eat the fruit without ill effects, but in humans the fruit produces stomach cramps and acts as a strong laxative (as indicated by the species name, "cathartica").

Rhamnus

Rhamnus cathartica

buckthorn [Blooms: May-Jun]

Rosinweed produces a panicle of sunflower-like blooms from the top of the stem and the tops of side stems (if any). Individual flowerheads are 2-3" across; they consist of 12-35 yellow, pistillate (female) ray florets and 70-200+ functionally male disc florets. The green bracts beneath the flowerheads are teardrop-shaped, partially overlapping in two or three layers, and sometimes covered with glandular hairs. The petals of the ray florets have two prominent longitudinal grooves and a tiny apical notch. Only the ray florets can produce seeds — a split style protrudes from a short tube at the base of the ray floret. The central disk is initially green but becomes yellow as the disk florets open; they are yellow, tubular, with five triangular lobes at their free end, with a column of brown stamens with the tips of very long, (non-functional) styles protruding from the tubular corolla. The fruit is a flat seed that develops from the ray florets. (The curious arrangement where only the ray florets can produce seeds while the disk florets are functionally male is true throughout the genus Silphium. The opposite is true in the true sunflowers, genus Helianthus.)

Silphium

Silphium integrifolium

rosinweed [Blooms: Jul-Sep]