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Small-flowered buttercup is a native species that has flowers similar to several other buttercups but is distinguished by its broad range of leaf shapes — other buttercups don't have this wide a variety of leaf shapes on a single plant. The flowers are stalked in groups of one to three on the end of the stems. Each flower is 1/4" across with five lance-shaped or triangular petals that are shorter than the sepals. There are five broadly rounded sepals, a ring of 5-10+ stamens with yellow anthers, and a central mound of green carpels, each with a pistil. After fertilization, the carpels enlarge and the central mound elongates until it is ovoid; the fruits (achenes) are shiny and have small beaks.

Ranunculus

Ranunculus abortivus

small-flowered buttercup [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]

Hispid buttercup is a native species that gets up to about a foot tall; plants tend to become more sprawling as they grow. Flowers are 3/4-1" across, arising from the leaf axils on stalks with short, appressed hairs. Each flower has five light green sepals shorter than the petals and with long hairs on the outer surface, five shiny, yellow petals, and a ring of 5-10+ yellow stamens around a central mound of yellowish-green pistils. There is often a region at the base of the petals that is translucent and green-tinged. The sepals may lie directly under the petals or may be reflected so they lie parallel to the flower stem. After fertilization, the central mass of the flower enlarges and the other parts of the flower wither and fall away. Maturing fruits are green, shiny, laterally compressed, with a sharply angled margin and long, straight, tapering beaks pointing up at about a 60° angle; the seedhead looks distinctly spikey.

Ranunculus

Ranunculus hispidus

hispid buttercup [Blooms: May-Jul]

Pennsylvania buttercup is a native plant that is formally listed as "imperiled" in Illinois (which is at the southern limit of its range east of the Mississippi). The flowers arise from leaf axils on short stalks. Individual flowers are small (1/8-1/4" across) with five yellowish-green sepals, five shiny, yellow, egg-shaped petals, and a ring of 5-10+ yellow stamens around a central mound of green carpels and pistils. The sepals are longer than the petals, are reflexed back on the flower stem, and are covered with long hairs on the hidden surface. After fertilization, the carpels enlarge and the central mound elongates; individual mature fruits are laterally compressed with straight to sightly curved (but not hooked) beaks. Pennsylvania buttercup tends to prefer wetlands and similar environments.

Ranunculus

Ranunculus pensylvanicus

Pennsylvania buttercup [Blooms: Jul-?]

Individual flowers of hairy buttercup have five sepals, each 1/8-1/4" long with a sharp transverse fold at their base such that the sepals point down (are reflexed), parallel to the stem. There are five petals that are 7-10 mm long and 4-8 mm wide, roughly egg shaped, with the upper surface a brilliant, glossy yellow. Finally, two to three dozen yellow stamens with yellow anthers surround a yellowish-green central ovary with plate-like segments radiating out from the center of the ovary, each with a blunt, short style. The fruit develops by an enlargement of each of these segments, which remain attached to each other. Hairy buttercup is easily confused with early buttercup (Ranunculus fascicularis), but the sepals of early buttercup lie parallel to the petals (horizontal) while the sepals of hairy buttercup have a distinct transverse fold at their base such that the sepals lie parallel to the floral stem, at a steep angle to the petals.

Ranunculus

Ranunculus sardous

hairy buttercup [Blooms: May-Jun]

Cursed crowfoot flowers occur on the ends of the upper stems. Individual flowers are 6-8 mm across with five yellowish-green sepals about the same length as the petals, five (sometimes three or four) yellow, rounded petals, a ring of 5-10+ short stamens with yellow anthers, and a central hemispherical to gumdrop-shaped mass of green pistils. After fertilization, the central mass of pistils enlarges and elongates, producing a cylindrical mass of flat, smooth, kidney-shaped 1 mm long seeds with short, straight beaks.

Ranunculus

Ranunculus sceleratus

cursed crowfoot [Blooms: May-Jul]

Upright prairie coneflower (aka, "Mexican hat") is a 1-3' tall plant native to North America but an exotic in Illinois; it looks like English plantain (Plantago lanceolata) dressed up for a party. The stems are green and longitudinally ridged; they bear alternate, pinnatifid leaves with 5-11 elongate, narrow lobes. The upper stems produce flower stalks (peduncles) 2-12" long, minutely grooved, and lacking leaves; the peduncles are very "wire-like." The flowerheads are 1.5-3" long cylinders composed of numerous brown or purplish disk florets that bloom from the bottom of the cylinder to the top; at the base of the cylinder are 4-12 ray florets with drooping, 1/2-1.5" long, oblong petals with notched tips that are yellow, maroon, or yellow with basal maroon patches (the "party skirt"). This plant is unmistakable when in bloom. The imaged flower was photographed in Bobolink Meadow in July, 2010; I have not seen a specimen since.

Ratibida

Ratibida columnifera

upright prairie coneflower [Blooms: Jul]

Grey-headed coneflower's composite flowerheads sit individually on the tips of long, thin, ridged stalks; they have up to 15 drooping, 2" long, yellow ray florets and a central 3/4" tall gumball- or egg-shaped cone of 100-200 disc florets. The ray florets are sterile; the disc florets have both stamens (5) and styles (1). Beneath the flowerhead are two series of long, narrowly-triangular bracts. The disc florets mature progressively from the bottom of the cone to the top; immature disc florets are light green or grey, mature disc florets are brown, giving the portion of the cone they cover a fuzzy appearance. (Thus the analogy implicit in the common name to a grey, bald pate peeking through a head of brown, fuzzy hair.) After fertilization, the cone becomes a mass of small (2-4 mm long), brown seeds (achenes) that are devoid of a tuft of hairs.

Ratibida

Ratibida pinnata

grey-headed coneflower [Blooms: Jun-Oct]

In Japanese knotweed, axils of the upper leaves produce slender, fuzzy spikes 2-4" long, covered with white or greenish flowers; more than one spike can arise from an axil. The flowers arise in groups of 3-6 from papery sheaths on the spikes. Individual flowers are sessile, about 8 mm long, with a funnel-shaped calyx, five petal-like sepals with wings on their outer faces, no petals, 6-8 stamens, and a tripartite stigma on top of a bullet-shaped green ovary. The fruit is a single shiny, black, three-angled seed with three broad, whitish, wings. Japanese knotweed is a highly aggressive invasive, luckily uncommon in Jackson Park. I know of three places in Jackson Park where it grows (it is a perennial); the Park District has eradicated it in one of these locations.

Reynoutria

Reynoutria japonica

Japanese knotweed [Blooms: Aug-Sep]

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]

Fragrant sumac is a native shrub that grows 2-8' tall. One-inch-long spikes of closely-packed flowers arise from leaf axils. Individual flowers are 1/8" long, tubular but less than twice as long as wide, with five greenish-yellow petals and a calyx of five short sepals fused at their bases; flowers are either perfect (with both male and female organs) or unisexual (either stamens only or pistils only). (If unisexual, all flowers on one plant are the same sex.) Male flowers have five stamens with yellow-orange anthers but no pistil; female flowers have a pistil with a Y-shaped tip but no stamens. After fertilization, the flowers are replaced by fruits 1/4-3/8" in diameter, roughly spherical, deep red, and exuberantly hairy; it contains a single stone (a seed with a hard coat). Fragrant sumac blooms before either smooth sumac or staghorn sumac and its fruit matures earlier.

Rhus

Rhus aromatica

fragrant sumac [Blooms: Apr-May]

Smooth sumac is dioecious — each plant produces only either male (staminate) or female (pistillate) flowers. Individual flowers are about 1/4" across with a green calyx with five teeth and a whitish green or yellowish green corolla with five spreading petals. The lobes and teeth range from lance-shaped to oval. Male flowers also have five stamens with large yellow anthers and style rudiments; female flowers have an ovary with three closely-packed, stout styles in the center and sometimes with rudiments of stamens. On female plants, after fertilization, the flowers are replaced with about 5 mm wide drupes containing a single straw-yellow stony seed. The fruits are initially green and densely covered with short hairs, turning an intense, deep red when mature.

Rhus

Rhus glabra

smooth sumac [Blooms: May-Jul]

In staghorn sumac, some upper stems bear clusters (panicles) of flowers that are up to 12" long and 6" across; pistillate (female) inflorescences (see below) tend to be more densely packed with flowers and smaller than the staminate (male) inflorescences. Individual flowers are 1/8-1/4" across with a five-lobed calyx, each lobe about as long as (and alternating with) the petals, and five spreading, oblong petals; both calyx and petals are yellowish-green. Staghorn sumac has a complicated sex life. Some plants have both perfect flowers (with both male and female organs) and unisexual flowers (male or female but not both) on the same individual. Other plants have flowers of only one sex (either male or female but not both). Female flowers have a central pistil with an orange-yellow, three-part stigma; male flowers have five stamens with large, bright yellow anthers. The fruits are very fuzzy, berry-like drupes about 1/4" across, deep red when ripe, each with a single seed. The velvety branches and fuzzy fruit distinguish this plant from other sumacs. A citrus-y summer drink can be made from an infusion of the fruits soaked in hot water for a few hours; just be sure to filter the infusion through a fine filter (coffee filters are good) as the hairs covering the fruit can irritate the throat. Add some sugar or honey to taste. The binomial "Rhus hirta" is occasionally used for staghorn sumac, but ITIS is clear that the accepted name is Rhus typhina.

Rhus

Rhus typhina

staghorn sumac [Blooms: May-Jul]

The tips of some short, lateral shoots of wild black currant produce clusters (racemes) of 6-15 flowers that are suspended by short pedicels from a central, drooping stalk 1-3" long. At the base of each pedicel is a 3/8" long yellowish bract. Individual flowers are 1/2" long, bell-shaped with a short tubular calyx with (1) five spreading, oblong, greenish-white apical lobes (sepals), (2) five squared-off whitish petals emerging from the tubular calyx and forming a ring-shaped wall, (3) five stamens, shorter than the petals, with cream-colored anthers, and (4) a green ovary with two styles that are fused except at their tips. The fruit consists of 3/8" wide, shiny berries, initially green, black when fully ripe, containing lots of tiny seeds. The berries are edible when cooked and have been used to make pies, jelly, or wines (if you can get to them before the birds do). Note that commercial black currants are derived from the European version of this species (Ribes nigrum), not Ribes americanum.

Ribes

Ribes americanum

wild black currant [Blooms: Apr-May]

Golden currant produces one- to three-inch-long clusters (racemes) of 5-18 drooping flowers from the leaf axils. Individual flowers are 3/4" long and across; the joined sepals are yellowish-green and tubular basally but abruptly flare into five bright golden-yellow, rectangular lobes with rounded tips. The petals are short (2-3 mm), rectangular structures that surround the throat of the corolla; they may be yellow or orange but are usually red or red-tipped. Between the petals are five stamens that extend to the tips of the petals, bearing white anthers; the styles are light green, fused to just below the stigmas, and protrude beyond the petals. The fruit is a small (1/4-3/8") edible berry with lots of seeds; fruit color is initially green but ranges from golden yellow to black when mature. Unlike gooseberries, this plant lacks spines and prickles; its large yellow flowers are distinctive. Golden currant is native to North America and was once very popular as an ornamental plant (and fruit for jams and jellies); it has probably escaped cultivation numerous times.

Ribes

Ribes aureum

golden currant [Blooms: Apr-May]

Missouri gooseberry produces groups (racemes or corymbs) of 1-3 flowers on a horizontal flower stalk near some leaf petioles; the 1/4-1/2" long flower pedicels droop downward, so the axis of the flower is vertical. An egg-shaped, sessile bract is present at the base of each flower stalk. Missouri gooseberry flowers are easy to overlook because they don't comport with one's usual idea of "flowers" — they are very elongate, as if viewed in a fun house mirror. The flowers have a very narrow, white or greenish-white, tubular calyx with 4-5 oblong, spreading or reflected sepal lobes as long as the calyx; five short, erect petals extending from the calyx; and 4-5 stamens that double the vertical length of the flower. Hidden inside, at the base of the calyx, is a smooth ovary topped by a single pistil with one style; only the style is visible externally, sometimes extending past the stamens during flowering. After fertilization, the flower parts wither and the ovary expands into a smooth, globular berry 6-12 mm in diameter containing numerous tiny seeds; the berry is initially green, turning dull red or dull purple when ripe. If you see a gooseberry in Jackson Park with a prickly surface on the fruit (looking like a miniature, green medieval mace), it is prickly gooseberry, Ribes cynosbati, which also has lobed leaves. I have yet to see prickly gooseberry in Jackson Park, but it is known to occur in northern Illinois.

Ribes

Ribes missouriense

Missouri gooseberry [Blooms: Apr-May]

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]