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Reed canary-grass is a very widespread species (the native range is circumboreal in the Northern Hemisphere) that is listed as "vulnerable" in Illinois. It is a wetland grass that reaches heights of 3-5 feet; plants tend to be widely spaced on Jackson Park although they are known to produce clonal colonies elsewhere. The leaves are flat, alternate, and evenly spaced along the culm. The leaf blades reach up to 12 long and 3/4" across; they are green or blue-gray and hairless with continuous (but rough-textured) margins. The leaf base is much wider than the culm (stem) which it clasps tightly; the leaf sheaths look like an extension of the leaf in both color and appearance. When reproductive (early-midsummer), the culms produce a narrowly-pyramidal panicle up to 10" long and 2-3" across of spikelets that bear the florets. Spikelets are initially green but fade over time to a light tan color. The stem and leaves all turn a diagnostic light tan during the late fall and winter; the leaves mostly remain attached.

Phalaris

Phalaris arundinacea

reed canary-grass [Blooms: May-?]

Common plantain is an introduced plant commonly found in lawns and disturbed areas. The flower stalks are erect, 4-20" long; the lower third is green and unadorned while the upper two-thirds is densely covered with 1/8" green flowers. Individual flowers consist of four green sepals with a green keel and membranous margins above a single green bract, four filamentous stamens with tan to purplish anthers, a single white style, and a four small, papery, petals. The flowers are wind-pollinated. The fruits are rounded, egg-shaped capsules about 1/8" long. Common plantain is nearly indistinguishable from (the native) black-seeded plantain (Plantago rugelii); the two species differ only in the details of the sepals and seed pods. (Common plantain's seed capsule is egg-shaped and splits around the middle; black-seeded plantain's seed capsule are 2-3 times longer than wide splits nearer the bottom.) One, more ephemeral, character may help distinguish the two species in the field. According to Minnesota Wildflowers, the base of the leaf stalks of the native species (Rugel's plantain, P. rugelii) are dark red or purple in color; the base of the leaf stalks of the exotic common plantain (P. major) are uniformly green. Rugel's plantain is probably as common and tolerant of a range of habitats as common plantain, but specimens of this plant tend to be reflexively referred to "common plantain."

Plantago

Plantago major

common plantain [?-Aug]

Eastern cottonwood is dioecious; flowers are either male or female and occur on separate trees. The flowers, whether staminate or pistillate, are produced on catkins 2-3" long; the flowers are wind pollinated. Male catkins are produced in clusters of 2-4 near branch tips; they are bright red or yellow, cylindrical, and densely covered with male florets. The male florets have a fringed bract at their base, above which is a basal disc with 30-40 reddish or yellowish stamens. Female catkins are solitary (not in groups), cylindrical, and green, covered with numerous female florets on slender petioles. Each female floret rests on a fringed bract above which is a dish-shaped three- or four-carpelled basal disc with a single, oval pistil about 8 mm long with 2-4 apical, yellowish, flattened stigmas with undulate margins. After fertilization, the female catkins elongate to a length of 4-6" while individual ovaries enlarge; at maturity, each fruit splits to release 30-50, 2 mm long, seeds suspended on cottony hairs. The seeds are both wind and water dispersed.

Populus

Populus deltoides

Eastern cottonwood [Blooms: Apr-May]

In late spring and early summer, curly pondweed produces both flowers and turions (a detachable, dormant bud, a.k.a. a "winter bud"). Cylindrical flower spikes 1-1.5" long arise from the tips of the stems or the axils of upper leaves; peduncles up to 3" long hold the flower spikes just above the water. Each flower spike may have 3-5 whorls of flowers. Individual flowers are tiny (3 mm across); they consist of four greenish-brown or greenish-red sepals, four stamens with a ladle-shaped appendage, and four ovules topped by a four-part style. Flowers may be pollinated by either wind or water. Fertilized ovules produce a dry seed (a maximum of four per flower) that is generally oval but asymmetrical in detail with a knobby keel along one edge and a long, curved beak or tooth at the opposite end. Seed germination has never been observed. Simultaneously, the plant produces turions — rosettes of small, holly-like leaves that overall have a cone-like appearance — from the tips of stems and leaf axils. After the fruits and the turions are released, the rest of the plant degenerates over the course of the summer. The turions sink to the bottom of the water body and root, forming small plants that overwinter.

Potamogeton

Potamogeton crispus

curly pondweed [Blooms: 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]

Male and female flowers of pin oakare spatially separated but often occur on the same branch. Female flowers have been reduced to only a short, green spike bearing three bright red styles; the female flowers emerge from leaf axils and may occur in clusters of up to three. The male flowers are borne on 1.5-4" long green catkins that dangle from bud clusters at the tip of the previous year's growth. The fruits are egg-shaped or elliptical (hence the species name) acorns 1/2-2/3" long with a deep reddish cap that covers about half the acorn.

Quercus

Quercus ellipsoidalis

Northern pin oak [Blooms: Apr–May]

In bur oaks, both male and female flowers are produced on the same tree, but they are widely separated; the flowers are wind pollinated. Male flowers are borne on drooping, yellowish-green catkins 2-5" long that hang from the tips of the previous year's twigs; individual male flowers consist of 5-20 stamens surrounded by a lobed calyx. Some sources (e.g., http://www.missouribotanicalgarden.org/plantfinder/PlantFinderDetails.aspx?taxonid=280704) assert that the female flowers of bur oak also occur on catkins, but this is incorrect. Instead, the female flowers occur alone or in groups of 2-3 that arise in the leaf axils of new leaves. Individual female flowers are about 3 mm (1/8") long; a short, reddish green stalk (a pistil) covered with appressed scales bears naked reddish-green or light green styles on its tip. The female flowers are wind pollinated. Both male and female flowers form after the leaves begin to unfurl; the male catkins precede the female flowers by one to several weeks. Fertilized female flowers produce one or two acorns; the acorns may be nearly sessile or hang from short (<1") stalks. Mature bur oak acorns are 1.5-2.5" long and the same across (including the caps) — they are the largest acorn of any oak. The caps (= cupules) cover at least half of the length of bur oak acorns, often so much that only a nubbin of the acorn is visible. The caps are covered with coarse scales that have an obvious keel and appear knobby; the marginal scales on the caps bear soft awns up to 8 mm (1/3") long that form a conspicuous fringe above the acorn — this is the "bur" that is referred to in the common name in analogy to the machine tool used for grinding. The acorns mature and germinate over a single summer; they do not need to be exposed to cold to germinate.

Quercus

Quercus macrocarpa

bur oak [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]

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]

Pale dock produces an inflorescence 4-12" long at the tip of the stem; branches in the inflorescence are few but are densely covered with numerous whorls of 10-20 small (1/8-1/4" long), green or yellow-green flowers drooping on 1/8-1/4" long pedicels. Individual flowers have six green tepals (three sepals and three similar petals) that spread at flowering to expose either six stamens or three styles, but close again after pollination. (Flowers are either pistillate (female) or staminate (male) and are wind pollinated.) After fertilization of the pistillate flowers, the fruit — a single seed in the middle of three equally-spaced wings — replaces the flower. Pale dock's seeds can persist in the soil for at least ten years.

Rumex

Rumex altissimus

pale dock [Blooms: May-Jun]

The inflorescence at the tip pf the stem in curly dock produces branching clusters with numerous whorls of 10-25 flowers dangling from slender pedicels. Flowers are tiny (1/8-1/4"), red- or yellow-green, with six tepals (three sepals and three very similar petals), three styles, or six stamens, or both; the flowers droop from a 1/4" pedicel. (The flowers are either pistillate (female), staminate (male), or perfect (both male and female organs). The flowers are wind pollinated. The tepals spread out when the flowers are mature, exposing the stamens and/or styles, then close up after pollination. The fruit is a single seed sandwiched in the center of three heart-shaped, papery membranes (derived from the tepals) set at 120° from each other, dark brown when mature. Note that more mature curly dock fruit can take on a distinct reddish tint, superficially looking like bitter dock fruit, but curly dock fruits will never show the long tooth- or finger-like projections from the edges of the wings that bitter dock exhibits.

Rumex

Rumex crispus

curly dock [Blooms: May-Jun]

The inflorescence of bitter dock is a panicle of whorled racemes up to 1' long. The greenish-red flowers droop from 1/2" pedicels. Individual flowers are 1/4" long with six tepals (six sepals and six similar petals) with pistillate (female) and male (staminate) flowers mixed in each inflorescence. Pistillate flowers have a single pistil, three styles with fringe-like, divided stigmas, and inner tepals that are (often) red; staminate flowers have six stamens and dull yellow inner tepals. After fertilization, the inner tepals of the pistillate flowers enlarge and surround an expanding, hard-shelled, three-sided seed with three membranous wings, each wing with 2-4 spiny teeth along their free edges. The fruits turn bright red as they mature.

Rumex

Rumex obtusifolius

bitter dock [Blooms: May-Jul]

Missouri River willow is dioecious — male and female florets (in the form of spike-like catkins) occur on separate plants. Catkins arise on one-year-old branches at about the same time as the leaves begin to emerge. Male catkins may be 1/2-2" long; each floret has two stamens with yellow anthers on their tips. Female catkins range from 3/4-2.5" long; the florets are yellowish-green and vase- or flask-shaped with an inflated base and a long beak that has a single protruding style. Both male and female catkins have a very small brown or bicolored bract at their bases that is covered with long, white hairs. After fertilization, female florets elongate as the catkin also elongates; the fruit is a yellowish to reddish green, hairless capsule, generally pear-shaped with a long beak. On maturity, the capsule splits to release seeds with long, attached, cottony hairs.

Salix

Salix eriocephala

Missouri River willow [Blooms: Apr]

Prairie willow is dioecious — plants produce either all male or all female inflorescences in the form of short catkins produced from one-year-old branches before the leaves emerge; a tiny black or bicolored bract covered in long, dense white hairs is present at the base of both male and female catkins. The florets lack both sepals and petals but both have a basal, hairy bract (regardless of sex). Male catkins are 1/4-1.25" long, elongating as they mature. Initially the male catkins are silvery (from long hairs) but become yellow or reddish from the numerous anthers. Individual male florets consist of a hairy, basal bract and a pair of stamens with cylindrical anthers initially purple, turning yellow, red, or orange. Female catkins are 1/2-3" long, also elongating as they mature. Individual female florets consist of the hairy bract and a hairy green ovary 4-8 mm long with an elongate beak densely covered with wooly hairs; a pair of stigmas protrude from the tip. After fertilization, the female florets transform into 1/4-1/2" long capsules, light brown at maturity, that split in two to release seeds surrounded by long, cottony hairs.

Salix

Salix humilis

prairie willow [Blooms: Apr-May]

Narrowleaf willow is dioecious — plants produce either all male or all female inflorescences (catkins) with the florets (male or female) spiraling around the catkin axis in a pseudo-whorl. Catkins are produced on one-year-old branches at the same time the leaves emerge. Male catkins are cylindrical, 3/4-2" long; they may be either erect or lean to one side but generally are ascending. Female catkins are also cylindrical, 1.5-3" long, initially green but turning light brown on maturity; they are usually terminal spikes on the new season's growth. Individual male florets consist of a single yellow, silky-hairy, oblong bract (quickly shed) and a pair of stamens with bright yellow anthers; the lower parts of the filaments are also covered by silky hairs. Individual female florets also have an oblong, basal bract that is shed; above that is a 1 mm long slender stalk supporting a bottle-shaped ovary 5-9 mm long with a pair of flat stigmas at its apex that appear to be four. After fertilization, the catkin elongates, and the ovary develops into a capsule that splits longitudinally to release the seeds when they are mature.

Salix

Salix interior

narrowleaf willow [Blooms: Apr-Jul]