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European bird cherry It has showy white flowers (so is widely planted as an ornamental) and reaches heights of 30-40'. Blooms are produced in elongate, cylindrical racemes of 15-50 flowers at the tips of twigs, similar to but shorter than those of chokecherry (Prunus virginia). Individual flowers consist of five green, broadly-spreading or reflexed sepals (longer than wide); five white or cream colored petals that are 1/4-3/8" long, oval but widest in the center; 10-30 stamens half the length of the petals around a cup-shaped, often green hypanthium (hairless externally); and a single central pistil. The fruit is a small, black drupe (cherry) with an extremely bitter taste to mammals, but it is much loved by birds, who disperse the pits. European bird cherry is very similar to another species present in Jackson Park, chokecherry. 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). It's not clear how much of this expansion is due to Park District policy and how much is due to natural seed dispersal.

Prunus

Prunus padus

European bird cherry [Blooms: Apr-May]

Peach flowers arise along young branches, blooming beginning before the leaves have opened in the spring; the flowers are usually solitary but occasionally occur in pairs. Individual flowers are 1-1.5" long consisting of a burgundy-colored calyx with five rounded apical lobes (sepals); five spreading pink (rarely, white) petals, oval with abruptly narrowed bases ("clawed"); 15-30 stamens with pink filaments and yellow to orange anthers; and a pistil with a single light green style nearly as long as the stamens. Fertilized flowers are replaced by green, fuzzy ovoids, eventually up to 3" long and across and containing a single seed; peach-colored when mature.

Prunus

Prunus persica

peach [Blooms: Apr-May]

Sand cherry is a 4-8' tall shrub; the Great Lakes variant of this species (Prunus pumila spp. pumila) is restricted to the states (and the Canadian province) that touch on the Great Lakes. Blooms occur in umbels of 1-3 flowers; flowers open before the leaves but may persist after some leaves have emerged. Individual flowers are about 1/2" across, consisting of five sepals with rounded tips that are about a third the length of the petals; five white, round- or egg-shaped petals; 10-30 white stamens with yellow anthers emerging from a reddish, cup-shaped hypanthium; and a single, central style. The fruit is a reddish-purple to black, shiny cherry (drupe) about 1/2" in diameter. Sand cherry is found along the shores of the Great Lakes on beaches (sandy, gravelly, or rocky), dunes, and the swales between dunes.

Prunus

Prunus pumila

sand cherry [Blooms: Apr-May]

Black cherry (Prunus serotina) is a is a deciduous tree that can grow up to 80' tall. It typically has a single central trunk below and leafy crown that is taller than wide. Flowers occur in racemes 4-6" long with 20-60 1/2" wide flowers packed around the elongated inflorescence. Individual flowers consist of five green, triangular sepals, five white petals broader at their distal tips and at least three times longer than the sepals, 10-30 stamens with yellow anthers around a reddish-orange hypanthium, and a single, central pistil with a flattened stigma. After fertilization, each flower produces a globoid, fleshy drupe about 1/4" across. The immature cherries are green; as they mature the fruit turns first dark red, they purple-black at maturity. These fruits are sweet but slightly bitter; the black cherry you buy in the grocery store is larger (at least 1/2" across), sweeter, and a species native to Eurasia (Prunus avium).

Prunus

Prunus serotina

black cherry [Blooms: May-June]

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]

triped squill is another early spring wildflower native to western Asia and the Caucasus; it tends to grow in clumps of plants 4-6" across. There are (only) two dark green, basal, hairless leaves up to 6" long and ~1/2" wide that widen towards their tips; the margins are smooth. A cluster (raceme) of 3-6 flowers are present on a stalk ("scape") 4-8" tall; overall, the cluster and scape resemble the related wild hyacinths. Each flower has six white tepals with a medial blue stripe. The filaments of the six stamens are flattened and fused together to form a white central, lobed, hollow cone that surrounds the style; the anthers are yellow and lie just inside the tip of the cone. This plant is one of the earliest to bloom in the spring in Jackson Park, but goes dormant in the late spring, basically biding its time until the next year. It prefers moist, well-drained soils.

Puschkinia

Puschkinia scilloides

striped squill [Blooms: Mar-Apr]

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]

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]