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Japanese flowering cherry is an exotic from East Asia widely grown in North America as an ornamental (for its showy spring flowers). The flowers occur is small clusters of 2-5 white, pale pink, or deeper pink flowers that (unlike most cherries) dangle face-down beneath the stems from short spurs. The fruit consists of small, round drupes that turn black when mature. Leaves, stems, and fruit, and seeds are toxic to mammals. Many of the cultivars of Japanese flowering cherry are highly hybridized and nearly unrecognizable as being derived from Prunus serrulata.

Prunus

Prunus serrulata

Japanese cherry [Blooms: Apr-May]

Chokecherry is a shrub or small tree 8-25' tall. Flowers occur in spectacular racemes ~6" long with 15-20 white, 1/2" wide, bowl-shaped flowers with an orange-yellow center (hypanthium); the flowers are attached to a central, greenish-yellow stalk. Individual flowers consist of five sepals (initially green, later turning yellow) shorter than the petals, five white petals that narrow sharply near their bases, 15-20 stamens about as long as the petals, and a pistil with a single style. Crushed leaves smell strongly of bitter almonds. Fruit is a red to black globular drupe <1/2" wide that contains a single hard-coated seed (stone) and has a VERY bitter taste; the seed contains high levels of hydrogen cyanide. The fruit is eaten by a wide variety of mammals and birds; the flesh of the fruit traditionally was one of the components of pemmican in indigenous cultures. (The hydrogen cyanide is not a danger unless the hard shell of the seed is broken open.) Chokecherry is similar to wild black cherry (Prunus serotina), but P. serotina has incurved teeth on its leaf margins. Chokecherry is very similar to an exotic also present in Jackson Park, European bird cherry (Prunus padus). European bird cherry tends to be more tree-like in habit than chokecherry and tends to have shorter stamens (half the length of the petals) than chokecherry (as long as the petals). Chokecherry in Jackson Park is often infested with black knot fungus (Dibotryon morbosum).

Prunus

Prunus virginiana

chokecherry [Blooms: Apr-May]

Hoptree (a.k.a., wafer ash) is a large shrub with a rounded, irregular crown and (usually) a robust central trunk up to 6" across. Hoptree may produce single-sex (male or female) or bisexual (male and female organs both present) flowers on the same tree. Individual flowers are about 1/4" across, regardless of gender. Perfect (bisexual) flowers have 4-5 greenish sepals, 4-5 narrow, creamy white petals, 4-5 stamens with hairy white bases and yellow anthers, and a single, flattened green pistil. Male flowers are more or less identical but lack the pistil; female flowers are more or less identical but lack the stamens. The fruits are single seeds 1-1.5" long with a broad, flattened, papery wing extending almost all the way around the seed.

Ptelea

Ptelea trifoliata

hoptree [Blooms: May-Jun]

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]

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-?]

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]

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]

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]

Prairie rose flowers arise from upper stems, either as single flowers or as groups (corymbs) of 2-4. Individual flowers are 1.5-2" across with five green, lance-shaped sepals half the length of the petals, five pink petals, a ring of numerous (~120) yellow stamens, and a button-like, flattened yellowish central cluster (the stylar disc) of short styles. The fruit is a round, 1/2" diameter rose hip, bright red when mature, with the withered remains of the five long sepals at its tip. Prairie rose prefers coarse, dry soils or sand. Prairie rose is most similar to pasture rose (Rosa carolina) but has hairless flower stalks rather than the glandular-hairy stalks of pasture rose, most flowers occur in groups of 2-4, and its leaves tend to have more leaflets (typically 9; pasture rose has 5-7).

Rosa

Rosa arkansana

prairie rose [Blooms: May-Jul]

Pasture rose flowers are usually solitary, ~2" across on pedicels covered with glandular hairs, with five bold pink (rarely white) petals, five green, pointed sepals covered with glandular hairs, ~100 bright yellow stamens, and a small yellow or yellow-orange stylar disk composed of ~40 pistils and their stigmas. The fruits are typical rose hips about 5/8" across, bright red when ripe; the glandular hairs on the pedicel and sepals persist but the sepals are deciduous and quickly fall off. The flowers are similar to purple-flowered raspberry (Rubus odoratus) but the leaves are completely different (odd-pinnate vs. palmate).

Rosa

Rosa carolina

pasture rose [Blooms: Jun-?]