Filtered (377)
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 upper stems of marsh yellow-cress end in one or more 2-8" long racemes of flowers; racemes may also develop from leaf axils. Flowers in bloom are restricted to the tip of the raceme; cylindrical seedpods (siliques) oriented perpendicular to the stem decorate the lower regions of the raceme. Individual flowers are tiny (about 3 mm long) with four greenish-yellow oblong sepals, four yellow spatulate petals, 4-6 stamens with yellow or light brown anthers, and a stout style with a two-lobed stigma. After fertilization, 3-10 mm long, dumbbell-shaped, hairless, green siliques containing two rows of tiny seeds develop. The siliques bear the remnant of the style on one end and 1/2" long pedicels on the other.

Rorippa

Rorippa palustris

marsh yellow-cress [Blooms: Jun-Aug]

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-?]

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]

Swamp rose flowers arise from the upper stems as single flowers or corymbs of 2-4 flowers. The flowers are 1.5-3" across, with five green, lance-shaped sepals, five pale- or rosy-pink, oval or heart-shaped petals, a ring of about two hundred yellow stamens, and a flat central disc of 24-50 styles that is pink or orange-red (much less often, yellow). The sepals and pedicels are covered with glandular hairs. The fruits are typical rose hips but are quite small (3/8" across, pea-sized), bright red when ripe.

Rosa

Rosa palustris

swamp rose [Blooms: May-Jun]

Rugosa rose flowers are 2-3" across; they have five sepals covered with glandular hairs, five magenta (more rarely pink or white), wrinkled petals, over 100 yellow stamens, and a yellow, flat stylar disc in the center of the flower. The fruits are typical rose hips about 1" across, bright red when ripe. Rugosa rose prefers sandy habitats and sites prone to water stress (e.g., roadsides where salt washes off the roads). The wrinkled leaves and magenta petals, profuse straight thorns/prickles, and large rose hips are distinguishing characters of rugosa rose.

Rosa

Rosa rugosa

rugosa rose [Blooms: May-Jul]

Climbing wild rose flowers are 2.5-3" across with five green sepals five times longer than wide (reflexed, then shed soon after the flowers open); five pale fuchsia to pink petals, usually with a shallow terminal notch; a ring of about 200 golden stamens; and a tall, yellow stylar column with a terminal knob in the center of the flower. (The only other local species with a stylar column is multiflora rose, Rosa multiflora.) The fruits are typical rose hips, bright red when mature, less than 1/2" wide, with no trace of the sepals.

Rosa

Rosa setigera

climbing wild rose [Blooms: Jun -Jul]

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]

Purple-flowered raspberry's flowers are large (up to 2-3") with five sepals densely covered with reddish glandular hairs, bluntly triangular, about half the length of the petals with long, thread-like tips; five magenta, rounded, laterally overlapping petals surrounding a compact ring of 20-100 thread-like stamens with yellow anthers; and a central mound of several hundred pale yellow, club-shaped styles. The fruit is a typical drupe, 3/4" in diameter, reddish-pink when mature, more flattened than a commercial raspberry. It can be hard to find on the plant — it is very popular with birds. Between the maple-like leaves and the showy, magenta flowers, purple-flowered raspberry is impossible to confuse with any other Rubus spp. in Illinois. Purple-flowered raspberry prefers partial shade (like woodland edges); it is critically endangered in Illinois.

Rubus

Rubus odoratus

purple-flowered raspberry [Blooms: Apr/May-Aug]

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]

Orange coneflower (aka, Sullivant's coneflower) is a short sunflower (1.5-2.5') similar to black-eyed susan but the stems are green (not red) and are sparsely (rather than very) hairy with pronounced grooves; overall orange sunflower is less hairy than black-eyed susan. The stem leaves are alternate, about twice as long as wide, up to 5" long but decreasing in size and becoming narrower up the stem; they have toothed margins, taper to a short, winged petiole (lacking in black-eyed susan), and have three main veins (one central and two submarginal). The petioles are either sessile or clasp the stem. The flowerheads are 2-3" across, produced on the apex of the stems; each flowerhead has 10-20 yellow or orange (sterile) ray florets with the petal tips notched; the numerous (50 to over 500) disk florets are tubular and dark brownish-purple with five small lobes around their upper rim and a divided style. Petals that are yellow-colored often have orange bases. This species can be highly variable.

Rudbeckia

Rudbeckia fulgida

orange coneflower [Blooms: Jul-Aug]