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Water plantain is another plantain that's not a plantain, but it does look like one. This plant is an emergent aquatic with a basal rosette of large (up to 7"x 4"), hairless leaves with long petioles that are filled with distinctive spongy tissue (like a cellular foam); the leaves are (largely) parallel-veined. A tall (up to 3') highly-branched, whorled inflorescence rises from the center of the basal rosette; at the tip of each branch is a single 1/4" wide flower with three white petals (with a spot of yellow at their bases), three green sepals (with transparent margins) about half the length of the petals, and six stamens surrounding a greenish center that bears 1-2 dozen pistils. Water plantain is apparently popular with muskrats. Small-flowered water plantain (Alisma subcordatum) is more common in Illinois, but not known from Jackson Park; water plantain and small-flowered water plantain are nearly identical, but the latter has smaller flowers (1/8") and the petals and sepals on the flower are the same length.

Alisma

Alisma triviale

northern water-plantain [Blooms: Jun-Aug]

A short, sparsely-branched plant with alternate leaves. Flowers are clustered at the apex of the plant. Each 1/4"-3/8" wide flower has 4 white petals, 4 light green sepals, 6 stamens with yellow anthers and a stout, cylindrical style; the stigma is a flat disc. Garlic mustard's leaves are superficially similar to ground ivy (Glechoma hederacea), but less rounded; the flowers of each species are distinctive. A highly aggressive woodland invader introduced from Eurasia as an edible herb.

Alliaria

Alliaria petiolata

garlic mustard [Blooms: Apr-Jul]

Wild garlic's flower stalk holds a 1-2" wide inflorescence surrounded by 2-3 bracts; the bracts dry to a papery, off-white membrane tapering to a long point that contains flower buds on a pedicle, bulblets without pedicles, or both. When open, the flowers (~1/2" across) are each elevated on a 3/4" pedicle and exhibit six white, light pink or pink, sharply pointed tepals (= petals + sepals), six stamens, and a central light green ovary with a single style. Allium canadense is the most common Allium here; it can be distinguished from other native species by the presence of the aerial bulblets. The other common species in Jackson Park (nodding onion, Allium cernuum) is easily distinguished by the "nodding" of the entire inflorescence. (Neither of these is the "wild onion" Chicago is named for; that is Allium tricoccum.)

Allium

Allium canadense

wild garlic [Blooms: Jun-?]

Nodding onion's flower stalks are 12-18" tall, smooth, nearly vertical, and bend 180° at their tips (like a shepherd's crook); the ~2" wide flower cluster hangs below. Each of the 40-60 flowers hangs from a 1/2-1" hairless pedicel; each white, light pink, or light lavender flower has six tepals (three true petals and three similar-appearing sepals), six stamens (with yellow anthers) that extend well beyond the petals, and a single ovary with a style at least as long as the stamens. This is our only wild onion that "nods" so should be easy to identify. It's very popular with bees.

Allium

Allium cernuum

nodding onion [Blooms: Jul/Aug–?]

Wild leeks (Allium tricoccum) (a.k.a., "ramps") is an herbaceous native perennial found in the north-east quarter of the U.S. and the eastern provinces of Canada. It is most common in moist hardwood forests but is threatened by over-harvesting. It is listed as "Vulnerable in Illinois" [https://explorer.natureserve.org/Taxon/ELEMENT_GLOBAL.2.138691/Allium_tricoccum_var_tricoccum]. In early spring, the bulb of a wild leek produces 2-3 leaves that are each 4-9" long and 1.5-3.5" across with petioles that are reddish to maroon, hairless, and wrapped in a sheath basally. The leaves wither by early summer (before flowering). Later (early to mid-summer) the bulb produces a naked flower stalk 6-18" tall; the stalk is hairless, circular in section, and pale green to maroon with a papery sheath at its base. At the apex of the stalk is a single, spherical umbel, 1-2" across, of 20-40 white flowers, with a pair of bracts at the base of the umbel when fresh. Individual flowers are about 1/4" across; the flowers contain six white to translucent tepals (6-7 mm long, three with a reddish tip); a light green to pale yellow ovary; six, 6 mm long, stamens with pale yellow anthers that extend beyond the tips of the tepals; and a single, white 3-4 mm long style that extends past the three lobes of the ovary but not beyond the anthers. The stigma tiny and spherical. Fertilized flowers produce a three-celled seed capsule, each cell containing a single globoid seed that turns glossy black at maturity. Wild leeks are denizens of hardwood forests with rich, loamy soils. The leaves and bulbs are edible, but you really shouldn't — this plant depends on only a couple of weeks of photosynthesis to produce its leaves and flowers and is highly vulnerable to overexploitation by humans. If you see one of these plants, smile and know that you have been blessed. Then walk away.

Allium

Allium tricoccum

wild leeks [Blooms: Jun?]

Black alder is monoecious and produces separate male (staminate) and female (pistillate) florets on the same tree, both partially formed in the season before they bloom and overwintering before they become fertile. Male catkins occur in clusters of 2-5 reddish-yellow catkins, each 2-3" long when mature, narrowly cylindrical, and drooping. Male florets occur in clusters of 3-6 along the catkins, partially hidden by oval, brown bractlets. Each male floret consists of a four-lobed calyx and four stamens; petals are absent. The female florets are produced in sparse, open, branched clusters of reddish cone-like catkins, each initially about 1/4" long but growing to 3/4-1" long and 1/2" across. Within each female cone, female florets occur in clusters of 2-3, partially hidden by bractlets. Each female floret consists of a naked ovary with a pair of tiny styles at its tip that are wind pollinated. After fertilization, the male catkins wither; the bractlets of the female catkins become brown and woody, producing a very pine-like cone with the seeds nestled beneath the bractlets. The egg-shaped, flattened seeds are formally samaras, but the wing is reduced to narrow ridges. The female cones can persist through the winter.

Alnus

Alnus glutinosa

black alder [Blooms: Mar-Apr]

The end of green/red amaranthus stem bears a bristly panicle of tiny flowers up to 18" tall; the flowers are either staminate (male) or pistillate (female), but both occur on each plant. The flowers are wind pollinated. Flowers lack petals but have five pink sepals 2 mm long with pointed tips (which, together with associated 3-4 mm long, red bracts, produce the bristly appearance). Male flowers have five stamens while female flowers have a single ovary with three stigmas.

Amaranthus

Amaranthus hybridus

green/red amaranth [Blooms: Sep-?]

At the apex of the stem of Palmer's amaranth is a panicle up to 18" long covered with tiny green flowers that are wind-pollinated. Flowers have 4-5 petals. Individual plants produce either staminate (male) or pistillate (female flowers) but not both; perfect flowers are unknown.

Amaranthus

Amaranthus palmeri

Palmer's amaranth [Blooms: Aug–?]

The tip of the stem of redroot amaranth produces a panicle of greenish-white flowers; smaller panicles of flowers also arise from the axils of the leaves in the upper half of the plant. Both male (staminate) and female (pistillate) flowers appear in the same inflorescence; perfect flowers are absent. Individual flowers lack petals but have 5 white tepals that are about 3 mm long and one or more small (3-6 mm) green, bracts under the flower whose midrib extends to form a spine; male flowers also have 3-5 yellow stamens, while female flowers also have an ovary with a 3-parted style on the top of the ovary.

Amaranthus

Amaranthus retroflexus

redroot amaranth [Blooms: Aug-Oct]

Common ragweed is a highly branched, weedy plant that gets about 3' tall. Numerous stems bear cylindrical flower spikes 1-6" long and 1/4" wide; the flowers are tiny (1/8"), all male (except near the base of the spike) in cup-like involucres that are initially green but turn yellowish-green with age, bead-like, hanging from short stalks. The actual male flowers are hidden in the involucre, lack petals, have numerous yellow anthers and (notoriously) produce copious yellow pollen that is carried by the wind; female flowers are enclosed in leafy bracts with protruding paired white styles, and occur in cryptic clusters on the stems below the flower spikes and in leaf axils. If you suffer from seasonal allergies, this plant and its cousin, giant ragweed, are the culprits, NOT the unfairly maligned goldenrod (which has sticky pollen that never gets airborne). Common ragweed has pinnatifid (pinnate-like) leaves; giant ragweed has deeply-lobed leaves that appear palmate.

Ambrosia

Ambrosia artemisiifolia

common ragweed [Blooms: Aug-?]

Male (staminate) and female (pistillate) flowers are physically separated on Western ragweed plants with the male flowers on spike-like racemes 1-6" long that arise from the upper stems, while female flowers occur more basally in small clusters at the base of the spike, along stems, or from leaf axils. Individual staminate flowerheads occur along the entire length of the spike, facing in all directions. They are 2-5 mm across, drooping from 1-4 mm long peduncles and developing a short, bell-like shape as they mature; they are covered by 3-5 oval, fuzzy phyllaries (bracts) in a single series where the lower half of each phyllary is fused to the other phyllaries. Beneath the phyllaries are approximately four staminate florets, each bearing five stamens with pale yellow anthers. The pistillate flowerheads are egg shaped and occur in clusters with a basal bract up to 1.25" long; pairs of smaller bracts lie just below each individual pistillate flowerhead. Pistillate flowerheads each sit in a cup of fused phyllaries 8 mm long and 3 mm across that has several tooth-like projections; each cup holds a single pistillate floret with a bifurcated style protruding from the apex of the floret. The florets are wind pollinated. Like other Ambrosia species in Jackson Park (common ragweed and giant ragweed), Western ragweed may contribute to hay fever symptoms. Western and common ragweed are similar to each other, but Western ragweed (almost always) has simple-pinnate leaves while common ragweed has double-pinnate leaves that are more deeply lobed and fern-like; Western ragweed is the hairier of the two.

Ambrosia

Ambrosia psilostachya

Western ragweed [Blooms: ?-Nov]

Giant ragweed is a much larger (up to 12' tall) cousin of common ragweed (A. artemisiifolia) but similarly bushy and weedy, with a candelabra-like appearance in the upper parts of the plant. The upper stems bear 3-6" long flower spikes, all male (except near the base of the spike) in 1/8" wide cup-like involucres that are initially green but turn yellowish-green with age, hanging from short stalks. The actual male flowers are hidden in the involucre, lack petals, have numerous yellow anthers and (notoriously) produce copious yellow pollen that is carried by the wind; female flowers are enclosed in leafy bracts with protruding paired white styles, and occur in cryptic clusters on the stems below the flower spikes and in leaf axils. If you suffer from seasonal allergies, this plant and its cousin, common ragweed, are the culprits, NOT the unfairly maligned goldenrod (which has sticky pollen that never gets airborne). Common ragweed has pinnatifid (pinnate-like) leaves; giant ragweed has deeply-lobed leaves that appear palmate.

Ambrosia

Ambrosia trifida

great ragweed [Blooms: Aug-Sep]

Downy serviceberry is a shrub or small tree 10-30' tall that blooms very early in the spring, before (most) leaf emergence; this is the most common Amelanchier sp. in Illinois. Downy serviceberry flowers bloom in a cluster of 5-12 before or early in leaf emergence. (Emerging leaves are folded and bronze-tinged.) Flowers are 1" across with a short, light green, a hairy calyx with five narrow triangular teeth 1/3 the length of the petals that are strongly bent back towards the stem; five narrow, oblong white petals; 15-20 stamens with creamy yellow anthers; a hairless green ovary; and a green pistil with a single five-parted style. Downy serviceberry flowers can be easily distinguished from Wiegand's shadbush (Amelanchier interior); the former has a hairless ovary while the latter has an ovary whose top is densely covered with wooly hairs. The very hairy undersides of downy serviceberry leaves are also a good clue to its identity, although other Amelanchier spp. also have (less) hairy leaves.

Amelanchier

Amelanchier arborea

downy serviceberry [Blooms: Apr-May]

Wiegand's shadbush (aka, serviceberry) is a shrub or small tree up to 10m tall, uncommon in Illinois and restricted to the northeastern portion of the state. The flowers bloom in clusters of 6-12 simultaneously with leaf emergence. (Emerging leaves are folded and bronze-tinged.) The flowers are 1" across with a short, light green, hairy calyx with five narrow triangular teeth 1/3 the length of the petals, strongly bent back towards the stem; five narrow, oblong white petals; 18-20 stamens with creamy yellow anthers; a characteristic green ovary densely hairy on the top; and a green pistil with a single five-parted style. Wiegand's shadbush flowers can be easily distinguished from downy serviceberry (A. arborea); the former has an ovary whose top is densely covered with wooly hairs while the latter has a hairless ovary.

Amelanchier

Amelanchier interior

Wiegand's shadbush [Blooms: Apr-May]

Marram grass forms a culm that remains short (~2") if no inflorescence is produced but reaches heights of 30" with an inflorescence. Culms produce a 6-12" long spike-like panicles of single-flowered spikelets each 9-15 mm long. Flowers are wind-pollinated, as is common in grasses. This plant is endangered in Illinois and is restricted to beaches along the Lake Michigan shoreline where it is often the dominant grass.

Ammophila

Ammophila breviligulata

marram grass [Blooms: Jul-?]

Lead plant is a sprawling bush 1-3' tall. the stems, leaves, flower spikes, and flower calyxes are densely covered with white, wooly hairs (giving the appearance of a metallic surface). The flower spikes are up to 6" long; they arise from the ends of branches. Flowers are 1/4" long, purple with reddish stamens and golden anthers; there is a single petal on the upper side of the flower that is initially tubular but opens after pollination to nearly flat (horizontal). Lead plant is considered an indicator of high-quality habitat; its tap roots can reach up to 5 m long. The flowers of lead plant look like false indigo (Amorpha fruticosa), but the latter is a much larger shrub.

Amorpha

Amorpha canescens

lead plant [Blooms: Jun-Sep]

Sharp-lobed hepatica is an early-blooming, woodland wildflower with distinctive 3-lobed, superficially palmate, variegated basal leaves on long petioles. The flowers are 1" across, borne on naked, reddish, hairy stalks ~4" long. Flowers consists of 5-11 (typically 6) blue, white, or lavender, oblong petals (actually, sepals), copious white stamens, and numerous green carpels; behind the flower are 3 reddish, hairy bracts shorter than the petals. ITIS considers Hepatica acutiloba a junior synonym of Anemone acutiloba; the USDA Plants Database, IUCN Red List, and NatureServe Explorer considers H. acutiloba as a junior synonym of Hepatica nobilis. All agree it is "sharplobed hepatica." The roundlobed hepatica (which is either a variety of sharplobed hepatica or a separate species, depending on which authority you prefer) is identical except that the lobes on the leaves are smoothly rounded.

Anemone

Anemone acutiloba

sharp-lobed hepatica [Blooms: Apr]

The petals (actually, sepals) of Canada anemone flowers are rounded; the pistillate cone in the center of the flower is approximately hemispherical and less than 10% of the flower width. The fruit is a round cluster of flattened seeds. The five-lobed leaves of Canada anemone are superficially similar to those of wild geranium (Geranium maculatum) but are sessile, not borne on petioles. Canada anemone is the commonest flower in Jackson Park in the late spring and summer.

Anemone

Anemone canadensis

Canada anemone [Blooms: May–Sept]