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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]

Sweet mock-orange inflorescences are racemes with 5-7 fragrant flowers; the most basal pair of flowers arise directly from the leaf axils. Individual flowers are 1-1.5" across, have four triangular green sepals, four brilliant white petals, 20-50 white stamens with orange anthers, and four white styles with yellow-orange stigmas. The styles are closely appressed proximally, separate distally.

Philadelphus

Philadelphus coronarius

sweet mock-orange [Blooms: May-Jun]

Cleft phlox flowers are supported by 1" pedicels, are 3/4" across, white or pale violet, with a tubular corolla that flares into five petal-like lobes that are each deeply cleft at their tips; the throat is very narrow. A three-lobed stigma and the orange anthers of the stamens lie just within the opening to the throat of the flower. Cleft phlox is endemic to the Midwest. The cleft petal lobes distinguish cleft phlox from all other Phlox species.

Phlox

Phlox bifida

cleft phlox [Blooms: Apr-?]

Woodland phlox is a 1-1.5' tall plant with a fuzzy to hairy stem, light green or reddish brown in color. Leaves are opposite (or sometimes in a three-leaf whorl), sessile or clasping the stem, three times longer than wide, lance-shaped with smooth margins, and fuzzy to hairy overall with short hairs around the margins. The flowers are 1" across, pale blue-violet, lavender, or (rarely) white, and with a long, narrow tubular throat that abruptly flares into five petal-like, spoon-shaped lobes. The calyx is green or reddish-green, hairy, with five long, narrow teeth almost half the length of the flower, spreading near their tips. The five stamens and style are hidden within the throat. Woodland phlox has relatively broader leaves than other Phlox species and has a more intense blue-violet (and less pink) color.

Phlox

Phlox divaricata

woodland phlox [Blooms: Apr-May]

Smooth phlox is a 1-2' tall plant with an unbranched, hairless stem topped with a slightly domed cluster of 3-20 pink or lavender flowers. Each flower is about 3/4" across and has a long, tubular throat that abruptly flares into five petal-like lobes; each lobe is wedge-shaped and overlaps the next lobe clockwise. The calyx (also hairless) consists of five triangular segments that taper rapidly to sharp points; the calyx is <1/3 the length of the corolla tube. The five stamens and single style with a three-part stigma either lie within the corolla tube or are just visible in the throat. After fertilization, a narrow seed capsule filled with numerous seeds fills the persistant calyx. Smooth phlox prefers moist to wet habitats. Smooth phlox flowers resemble prairie phlox (P. bifida) but the latter species is quite hairy on the stems, leaves, and the exterior of the flower (the calyx); smooth phlox is hairless. Checking the hairiness (or lack thereof) of the calyx is the quickest way to tell prairie phlox from smooth phlox.

Phlox

Phlox glaberrima interior

smooth phlox [Blooms: Jun-Aug]

Prairie phlox is a compact, single-stemmed, plant 1/2-1.75' tall with (typically) a dome-shaped cluster of flowers at the apex. Individual flowers are 1/2-3/4" across, pink or lavender (rarely white); the corolla is tubular with five wedge-shaped, petal-like lobes often with darker markings (nectar guides) near the throat; the corolla is hairy on all external surfaces. The throat is very narrow; the five stamens with yellow anthers are recessed but just visible. The very short, tubular, hairy calyx base is green, with five long, narrow teeth that extend parallel to the narrow throat (also hairy) of the corolla. The fruit is oval and shorter than the calyx (in which it develops); when ripe, the capsule splits explosively, flinging the seeds in all directions. The species name ("pilosa") means "hairy" in Latin, and this species is indeed hairy on almost every surface. Prairie phlox flowers resemble smooth phlox (P. glaberrima) and, to a lesser extent, woodland phlox (P. divaricata), but the former species is quite hairy on the stems, leaves, and the exterior of the flower (the calyx); smooth phlox is hairless. Checking the hairiness (or lack thereof) of the calyx is the quickest way to tell prairie phlox from smooth phlox; checking the hairiness of the exterior of the corolla tube will distinguish woodland phlox (hairless) from prairie phlox (hairy).

Phlox

Phlox pilosa

prairie phlox [Blooms: Apr-Jun]

Mayapple produces a single, hairless stem that branches no more than once; each stem thus has either a single leaf (infertile stems) or two leaves (fertile stems). Fertile stems produce a solitary nodding flower, 2-3" across, that is hidden beneath the leaves where the two leaves branch on the stem. The flowers contain 6-9 brilliant white petals and a ring of 12-18 tan stamens with large, banana-shaped anthers, all surrounding a surprisingly large, yellow ovary topped with a button of a stigmata. The fruit is a large (1.5" long), ellipsoidal berry, yellow when ripe. All parts of the plant are poisonous including the green fruit, but the ripe (yellow) fruit is edible (in small quantities).

Podophyllum

Podophyllum peltatum

mayapple [Blooms: Apr-May]

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]

Jetbead flowers are solitary, arising on the tips of the green twigs. Flowers are elevated on 1/4-1/2" long stalks. There are four green sepals at the base of the flower, each with a bractlet half the length of the sepals that is located below the intersection of each pair of sepals. Four white, nearly circular petals alternate in position with the sepals. A greenish hypanthium covers the center of the flower with a four-lobed ridge marking its edges. Numerous (30-60) stamens with white filaments and yellow anthers, usually in four distinct clusters, lie inside the ridge; the stamens surround four pistils, each with a single style and a circular, terminal stigma. After fertilization, 1-4 fruits develop in the center of the flower that turn shiny black at maturity (the "jetbead"); the seeds remain attached to the persistant sepals until late in the fall and may persist through the winter.

Rhodotypos

Rhodotypos scandens

jetbead [Blooms: Apr-May]

Upper branches of elderberry end in flat to domed panicles of flowers 3-10" across. Individual flowers are about 1/4" across, with a green, cup-shaped calyx, a creamy white corolla with five petal-like lobes, five long, spreading stamens with white anthers, and a creamy white hemispherical ovary with 3-5 short styles; flowers occur in umbel-like panicles 10" across made of dozens of flowers. The fruits are <1/4" wide spherical drupes in starburst-like sprays, dark purple to black when mature. The flower stalks are light green, turning purplish as the fruit ripens. The raw fruit is sweet with a slightly bitter or astringent aftertaste but may induce nausea or diarrhea if eaten in more than small quantities. The fruit is widely used in a variety of herbal supplements (as infusions and extracts), jam, and herbal wine. Note that all parts of the plant including the sap (except the flesh of the fruit) contain toxic cyanide-producing glycosides; berries should be cooked before consumption.

Sambucus

Sambucus nigra

elderberry [Blooms: May-Jul]

Evening campion is an exotic from Europe that grows to be 2-3' tall. It is nominally a night-blooming species, but I've observed it in bloom throughout the day in shady areas. Male and female plants are separate. The upper stems end in clusters of one or more 1-1.5" long flowers. The "bladder" (the calyx) is covered with a fuzz of fine hairs and has dark green or reddish-purple lines running from pole to pole (10 lines in male flowers, 20 in female). The five petals are heart shaped (with the point towards the center of the flower) and are deeply cleft into two lobes; the petals form a fringe that makes a distinct collar around the opening to the floral tube. Female flowers have five emergent styles (rarely four or six); male flowers have 10 yellow stamens that barely emerge from the collar at the center of the flower. (Other local Silene sp. have three styles.) The fruit is brown, urn-shaped, and has 10 small teeth on the distal end (or five pairs if you prefer). (Five or six teeth total in S. noctiflora, S. stellata, and S. vulgaris.) Evening campion evolved a dioecious life history (separate male and female plants) about 11 million years ago. (Other species in the genus have "perfect" flowers with both male and female organs present and functional in the flowers.) The evolution and genomic history of the sex-determining Y chromosome (XX = female, XY = male) has been of considerable interest for the light it shines on the evolution of Y chromosomes in both plants and animals (Moraga et al. 2025. Science 387:630–636; Akagi et al. 2025. Science 387:637–643).

Silene

Silene latifolia

evening campion [Blooms: May-Aug]

Royal catchfly's bright red flowers are restricted to the upper regions of the plant as clusters arising from the tips of stems. Individual flowers are 3/4-1" across, have an elongate (1"), narrow, cylindrical calyx with 10 longitudinal ridges, five narrow red or scarlet petals that flare from the tip of the calyx, and stamens with gray anthers that protrude well beyond the opening to the calyx. There are three corkscrew-shaped, threadlike styles that develop after the stamens have matured; like the stamens, they protrude well outside the calyx opening. The fruit is a 1/2" long capsule, open at the top, with 6-8 spreading teeth around the lip. Royal catchfly is hummingbird and butterfly pollinated.

Silene

Silene regia

royal catchfly [Blooms: Jul-Aug]

Starry campion's main stem ends in a panicle of flowers up to 8" long and 3-4" across; additional panicles may arise on the lateral stems on robust plants. Flowers occur in groups of 2-3 on the ends of long, slender branches; the flowers rest directly on short (1/4") pedicels. Individual flowers are 3/4" across. Each flower consists of a bell shaped, light green, fuzzy calyx nearly as broad as it is long with five broad, triangular teeth on its free end; five white petals with a narrow base and a "fringe" of 8-12 narrow lobes on their free ends; 10 stamens with slender white filaments that extend well outside the throat; and three white styles. The styles emerge from a large, green, globular ovary in the middle of the flower. After fertilization, the calyx gets broader (nearly triangular in profile) as the ovary expands into a spherical green ball; the fruit is brown, urn-shaped, and has six teeth on the distal end. The flowers tend to close in bright midday light. They are usually pollinated by moths and, to a lesser extent, bumblebees.

Silene

Silene stellata

starry campion [Blooms: Jun-Jul]

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]

A cup plant may have 10-30 flowerheads in bloom at one time. Behind the flowerhead are two or three layers of green bracts; the outer layer is egg shaped with a triangular, pointed, recurving tip. Each sunflower-like flowerhead is about 3-4" across; it has 18-40 yellow ray florets (e.g., the petals) and 85-150 yellow disk florets. The ray florets have a bifurcated but functional style protruding from a short yellow tube at the base of the petal; the disc florets are initially green but transform into yellow, tubular corollas with a non-functional style protruding through the fully-functional stamen. (True throughout the genus Silphium. The opposite is true in the sunflowers, genus Helianthus, where the ray florets are functionally male and the disk florets are fertile, functional females.) The cup-like leaves and square stem distinguish cup plants from other prairie wildflowers.

Silphium

Silphium perfoliatum

cup plant [Blooms: Jul-Sep]