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The inflorescence of black locust is a drooping raceme (flower spike) 4-7" long, with a pale green central stalk (rachis) and petiole, covered in 3/4-1" long, pea-like flowers. Each flower consists of a white or light green tubular calyx with five triangular teeth, densely covered with short hairs, and five white petals — a vertical banner with a yellow spot at its base, two lateral petals forming a keel, and two more wings enclosing the keel. The stamens (with orange anthers) and a single style are hidden within the keel. The fruit is a drooping, green seedpod 2-4' long at maturity, when it is dark brown and laterally flattened, containing from 3-10, quarter-inch-long seeds. Black locust produces a hardwood that is extremely resistant to rot and was prized by boat and bridge builders, especially as a source for trenails. (A dowel used to join two pieces of wood by driving it through a slightly undersized hole bored through the pieces; see Eric Sloane, "A Reverence for Wood," p. 37.)

Robinia

Robinia pseudoacacia

black locust [Blooms: May-Jun]

Multiflora rose's flowering stalks produce abundant white flowers in panicles of up to 30 flowers — in full bloom, a multiflora rose shrub can be breathtaking. Individual flowers are about 1" across, each with five green sepals covered with glandular hairs, five oval white petals, a ring of 35-100+ stamens with bright yellow or orange anthers, and a greenish central column of styles with yellow stigmas. (The only other local species with a stylar column is climbing wild rose, Rosa setigera.) The fruit are 1/4" diameter typical rose hips, hairless, orange-red or red when mature; the sepal remnants are shed before maturity. There are at least two large multiflora rose shrubs on Wooded Island.

Rosa

Rosa multiflora

multiflora rose [Blooms: May-Jun]

Common blackberry canes produce leaves and actively grow in their first year (primocanes); in their second year, they switch to producing flowers and fruit (floricanes). Second-year canes produce cylindrical racemes (up to 8.5' long) on the tips of short lateral shoots, longer than wide, with about a dozen flowers; the peduncles and pedicels of the raceme are covered with conspicuous glandular-tipped hairs. Each flower is 1-2" wide, has five green, pointed, triangular sepals with a tail-like extension, densely covered with glandular and non-glandular hairs; five white, rounded, wrinkled petals; 20-100 creamy stamens with white or yellow anthers; and a green cluster of numerous (100+) slender styles. After fertilization, the central cluster of styles enlarges to form a typical blackberry (drupe) 3/4" long and a bit less than half as wide, initially white or green but turning red-black when mature. The fruit is popular with most birds and mammals (including humans), who subsequently disperse the seeds.

Rubus

Rubus allegheniensis

common blackberry [Blooms: May-June]

Young, densely-hairy, stems of common dewberry terminate in single flowers or corymbs of 2-3 (rarely five) flowers. Individual flowers are 1-1.25" across consisting of five green, lance-shaped, hairy and glandular-hairy sepals with a thin, narrow "tail" at the tip; five white, wrinkled petals longer than the sepals; numerous (20-100) stamens; and a cluster of 5-150 green carpels with their club-shaped styles in the center of the flower. Floral stems may also arise from the axils of leaves. The fruits are pretty typical compound drupes (aggregate fruit like blackberries) 1/2-3/4" across, usually tightly attached to the receptacle with relatively few drupelets (10-40 of the smaller sections of the fruit); ripe fruit are dark red to black and shiny (not pruinose).

Rubus

Rubus flagellaris

common dewberry [Blooms: May-Jun]

Second-year canes of Pennsylvania blackberry produce 2-4" (across) corymbs of flowers on the tips of short lateral shoots. Each flower is about one inch wide, has five green, largely hairless, lance-shaped sepals much shorter than the petals with a thin "tail" on their tips; five white, oblong, wrinkled petals, widest about a third of the way from the distal tip; 20-100 creamy stamens with white or yellow anthers; and a light green cluster of numerous (100+) styles. Lance-like stipules or large leafy bracts flank the base of the flower pedicel, the latter often partially hiding the flower. After fertilization, the central cluster of styles enlarges to form a typical blackberry (drupe) 3/4" long, initially white or green but turning black when mature. The fruit is popular with most birds and mammals (including humans), who subsequently disperse the seeds.

Rubus

Rubus pensilvanicus

Pennsylvania blackberry [Blooms: May-Jun]

Common arrowhead's flowering stalks are about as tall as the leaves, either angular or round in section. Branches of the inflorescence end in 2-5 whorls of 2-3 flowers; the terminal branch bears 3-9 whorls of 2-3 flowers. Beneath each whorl 2-3, 1/8-1/3" long, boat-shaped, green floral bracts unite. Male (staminate) flowers have 25-30 yellow stamens while female (pistillate) flowers have a central green sphere of carpels; the male flowers are located above the female flowers in each raceme. Perfect flowers (both male and female organs present) do occur but are rare. Individual flowers are about 1-1.5" across with three oval, green sepals and three rounded, white petals about twice the length of the sepals. Male flowers have 7-30 yellow stamens in the center of the flower; female flowers instead have a bur-like green cluster of hundreds of carpels and their spike-like pistils (which have terminal or lateral styles). The pistils form a dense spiral on the surface of the central green mass. After fertilization, the female flowers lose their petals and transform into a bur-like, brown fruit about 3/4" across when mature; the spikes on the bur are individual seeds (achenes) that have a large, fang-like projection at right angles to the main axis of the seed.

Sagittaria

Sagittaria latifolia

common arrowhead [Blooms: Aug – Sep]

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]

Bloodroot flowers are 1.5-3" across with 8-16 (typically 8) bright white petals, numerous stamens with golden yellow anthers, and an oval, green pistil with a pale yellow, two-lobed stigma at its tip. Two light green sepals are present in the floral bud but they drop off as soon as the flower begins to open. After fertilization, the ovary expands into a spindle-shaped seed capsule about 1" long, yellow when mature, that splits to release the seeds. The seeds are disbursed by ants that are attracted by the white, fleshy appendage (an elaiosome) on the bright red seed. The red sap is highly toxic, both externally and internally — it inhibits the cellular Na+/K+ ATPase enzyme and kills the cells. Avoid getting the sap on your skin and certainly avoid getting it in your eyes or on mucous membranes.

Sanguinaria

Sanguinaria canadensis

bloodroot [Blooms: Mar-Apr]

The tips of the upper stems of Canadian black snakeroot give rise to umbels 2.5" across of greenish white flowers; each umbel usually consists of 1-4 umbellets, each with 2-3 pistillate flowers or perfect flowers and 2-6 staminate flowers. In perfect flowers, the pistils develop (and are deployed) before the stamens develop; the pistillate stage persists for much longer. Each flower has a green calyx with five lance-like lobes slightly longer than the five greenish-white petals. Male and perfect flowers add five stamens with white anthers and lack the series of hooked spines of the pistillate flowers. Female and perfect flowers have ovaries densely covered with distinctive, neatly stacked series of long, hooked bristles arrayed perpendicular to the axis of the flower. The fruit is round, 3-5 mm long, covered in rows of those same hooked bristles; it splits on maturity to release the two seeds.

Sanicula

Sanicula canadensis

Canadian black snakeroot [Blooms: Jun-Jul]

Soapwort produces clusters of 3/4-1" flowers from the tips of terminal stems and branches. Individual flowers have a 1" long, green or reddish, sometimes hairy, cylindrical calyx; a corolla with five spreading (later reflexed), pink to white, oblong petals/lobes with a notched tip; 10 white stamens with pale yellow anthers that protrude from the throat of the flower; and a similarly protruding, divided white style. The calyx persists as an inflated seed capsule filled with 15-75 tiny dark brown, kidney-shaped seeds. Soapwort might be mistaken for a phlox, but the stamens and style in phlox are always hidden in the calyx tube, never protruding as in soapwort, and soapwort has leaves with three obvious longitudinal veins. Soapwort contains saponins in both the foliage and (especially) the seeds that make a frothy soap-like lather when boiled (and were once used as a soap substitute), but caution is recommended — the saponins are toxic. Herbivores generally avoid this plant.

Saponaria

Saponaria officinalis

soapwort [Blooms: Jun-Jul]

Mad-dog skullcap flower racemes may arise at the tips of the stems or from the axils of leaves. Each raceme is up to 6" long, containing 6-7 pairs of flowers; each flower has a short, basal leafy bract. Flowers are up to 8 mm long with a short, slender pedicel, a light green tubular calyx with two shallow lobes (the upper lobe with a dish-like projection), and a pale blue, lavender, or white, densely hairy, tubular corolla 5-8 mm long with a short, hood-like, upper lip and a slightly flared, three-lobed lower lip. Hidden inside the upper lip of the corolla are four stamens and a single bifurcated style. After fertilization, the calyx swells into a green capsule with includes the dish-like projection mentioned above, giving the capsule a unique appearance; inside is a cluster of four nutlets. The mouth of the calyx is visible as a thin slit beneath the projection.

Scutellaria

Scutellaria lateriflora

mad-dog skullcap [Blooms: Jul-Aug]

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]

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]

White blue-eyed grass is a native perennial, 6-12" tall with a tuft of basal leaves and flowering stalks that are grass-like (if you squint). The basal leaves are green, 1/8" across, and strap-like; they are shorter than the flowering stalks. The flowering stalks are weakly winged and have a pair of sessile spathes (bracts sheltering the inflorescence) at their tips. The spathes consist of a pair of 1" long reddish or light brownish green bracts backed by a 3" long leafy bract; an umbel of up to six flowers arises between the bracts but only one or two flowers are in bloom at any given time. Each flower is only about 1/2" across and is supported by a 1/2" long pedicel. The flower consists of six white or pale blue tepals with a yellow patch at their bases and narrow, dagger-like tips; a column of yellow or orange-yellow stamens fused along their length almost to the anthers; and a globoid, green ovary covered with fine hairs and sporting a style with three slender lobes. Fertilized flowers produce a ridged, globoid seed capsule, initially green but turning tan to brown as it matures.

Sisyrinchium

Sisyrinchium albidum

white blue-eyed grass [Blooms: May-?]

Water parsnip's upper stems end in 2-5" wide, flat-topped umbels of flowers with numerous (10-20) umbellets, each with 20-35 tiny (1/8" wide) flowers. At the base of the umbel are 6-10 narrow bracts that are curved down towards the stem. Each flower has a 3-5 mm long stalk; a short, light green calyx; five white, heart-shaped petals with incurved tips; five stamens that extend well outside the flower; and an ovary with two diverging styles. The fruits are 3 mm long, slightly laterally compressed, oblong, with strong ribbing; each fruit contains exactly two seeds.

Sium

Sium suave

water parsnip [Blooms: Jul-Aug]

Horsenettle's upper stems end in small clusters of 3/4" wide white or light violet flowers with wavy petal margins and hairy pedicels; clusters may also arise from leaf axils. Each flower has a green, hairy calyx with five lobes that taper gradually to sharp tips (typically slightly reflexed); five triangular petals that are fused at their bases; and five yellow, banana-shaped anthers 6-9 mm long surrounding a long, slim, light green style with a darker green, globular terminal stigma. After fertilization, the ovary expands into mature berries about 1/2" in diameter, initially green-striped, that look like yellow cherry tomatoes when mature; they are half enclosed in a papery derivative of the calyx.

Solanum

Solanum carolinense

horsenettle [Blooms: Jun-Aug]

Black nightshade produces solitary umbels 3/4" long usually, from the axils of middle and upper leaves; the flower pedicels are about 3/8" long. Flowers are 1/4-3/8" across consisting of five sepals partially fused at the base of the flower; five white petals, green at their base, sometimes with purple highlights on the outside of the petal, and usually curved backwards; five anthers and their thick filaments appressed to form a tight, bright yellow cylinder with a yellowish-green stem; and a slender style running up the center of the appressed anthers to just emerge from the tip as a green stigma. The fruit is a 1/4-3/8" tomato-like berry, initially green; mature berries are black. The foliage and unripe fruit contain the alkaloid solanum and are toxic.

Solanum

Solanum ptychanthum

black nightshade [Blooms: Jul-Sep]

Upland white goldenrod stems end in a flat-topped panicle 6" across of flowerheads; colonies can present a visually continuous surface of flowers. The flowerheads are 3/4-1" across on 1" stems; each flowerhead has 10-25 white, pistillate ray florets (no stamens) and 30-36 yellowish, perfect disc florets (with both pistils and stamens). The petal-like rays are bright white and spreading, sometimes with notched tips; they look very much like a generic aster flowerhead. The disk florets are dull white and tubular; the five stamens in each disk floret are conjoined and yellow, giving a yellowish cast to the disk. Behind the flowerhead are 4-5 series of hairless bracts (phyllaries), light green at their base, darker green at the tips, each phyllary with a prominent light green mid-vein; the phyllaries are 4 mm long in total. Upland white goldenrod is uncommon in most of northern Illinois except in the sandy soils near Lake Michigan. ITIS and the Flora of North America accept Solidago ptarmicoides as a valid species name; the USDA Plants Database and NatureServe Explorer consider S. ptarmicoides as a junior synonym of Oligoneuron album (as does illinoiswildflowers.info).

Solidago

Solidago ptarmicoides

upland white goldenrod [Blooms: Aug-Sep]