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The height of the stem and the leaves of Sullivant's milkweed are similar to common milkweed. Each plant produces 1-3 (total) flower clusters from the stem apex and adjacent leaf axils; each cluster is 2-4" across and has ~15-25 flowers, each ~1/2" across. The flower petals are pink to rich purple, with white bases; the hoods are usually noticeably lighter. The horns are laterally compressed (sickle-shaped) and their tips clearly overlap over the column.

Asclepias

Asclepias sullivantii

Sullivant's milkweed [Blooms: Jul-Aug]

Common milkweed's flowers arise from leaf axils, are 2.5-5" wide, hemispherical, and covered with typical 1/2" wide milkweed flowers ranging from light pink to reddish-purple; the petals, reflexed back around the base of the flower are darker than the hoods.

Asclepias

Asclepias syriaca

common milkweed [Blooms: Jun-Aug]

Butterfly weed has clusters of 8-25 flowers, in various shades of orange with touches of yellow or red, that arise from the stems and leaf axils. Individual flowers have a typical milkweed morphology, with the petals reflexed backwards over the flower stalk and the complex corona protruding. The central column of the corona in A. tuberosa is always yellow regardless of the shade of the remainder of the flower. This is the only Illinois milkweed with orange flowers and has narrower leaves than all other local milkweeds except whorled milkweed (A. verticillata, which has white flowers).

Asclepias

Asclepias tuberosa

butterfly milkweed [Blooms: Jun-Sep]

Whorled milkweed's flowers are white, occurring in small (1-3") clusters that rise from leaf axils. Individual flowers are typical milkweeds (except for their color), 1/4" across; horns are sickle-shaped, petals are white or greenish-white. Once you recognize that this plant IS a milkweed, given its grass-like leaves in whorls, it is impossible to mistake it for any other local species.

Asclepias

Asclepias verticillata

whorled milkweed [Blooms: Jul-Sep]

Canada milkvetch flower stalks are ~6" long, covered by numerous (up to 75) cream-colored, tubular flowers (right side of image). Individual flowers are 1/2-3/4" long, slightly drooping, with five petals making up the tube (like an elongated pea flower) and a short (~1/4") cylindrical calyx of the same color with five thin, green teeth; the tip of the upper petal is reflected upwards. The fruits (left side of image) are short, pea-like legumes packed tightly along the flower spike.

Astragalus

Astragalus canadensis

Canada milkvetch [Blooms: Jun-Aug]

White wild indigo is a striking plant that puts up 3-6' tall spikes of white flowers; the flower spikes alone are up to 2' long. Each flower is ~1" long and across with a elongate, triangular bract at the base of the flower pedicel. A short (1/2"), tubular, bluish-green calyx with four triangular teeth encloses the base of a white typical pea-like flower with a forward-leaning banner (one petal, folded up and back along the midline) and a pair of wings (two petals) that enclose a keel (two petals); the keel encloses ten green stamens with orange anthers and the single style.

Baptisia

Baptisia alba

white wild-indigo [Blooms: May-Aug]

Stems of cream wild indigo terminate in 3-9" long flower spikes that sprawl laterally or arch. Each flower is ~1" long and across with a short (1/2"), tubular, light green to light purple calyx with 4-5 triangular teeth, a creamy-yellow (or very yellow) typical pea-like flower with a vertical banner (one petal) and a pair of wings (two petals) that enclose a keel (two petals); the keel encloses ten stamens and the single style. Flowers are held on ~1" long pedicels; at the base of each pedicel, a lance-shaped, 1/2-1" long bract is sessile on the flower stalk. This is our earliest-blooming wild indigo. Flower color, the profuse hairs, and the bracts at the base of each flower pedicel are sufficient to positively identify cream wild indigo.

Baptisia

Baptisia bracteata

cream wild-indigo [Blooms: May-Jun]

Yellow mustard produces inflorescences at the apices of the stems; individual flowers are 3/8" across with four yellowish-green sepals, four yellow petals, six stamens with yellow anthers, and a single pistil with a robust style.

Barbarea

Barbarea vulgaris

yellow rocket [Blooms: Apr-May]

River birch male (left) and female (right) catkins. Individual (highly modified) flowers are distributed over the surface of the catkins.

Betula

Betula nigra

river birch [Blooms: Apr-Jun]

Spanish needles flowers are 1/2" long and 1/4" across; they occur individually on the end of long peduncles. Each flower has 3-5 (sometimes zero) ovoid, yellow, petal-like ray florets around 12-27 yellow, tubular disc florets, each with five small lobes at their tips, 5 stamens, and a bifurcated style. Even in full bloom, the flowers look like buds. After fertilization, each flower produces needle-like, brown, four-angled, barbed seeds, each 1/2-3/4" long, that radiate in all directions from the base of the old flower.

Bidens

Bidens bipinnata

Spanish needles [Blooms: Aug-Sep]

Nodding bur-marigold's flowers usually have eight ray florets ("petals") that are elliptical; the flower is 1-2" across with the flower stem arising from leaf axil. Flowers nod down with age. The phyllaries at the base of the flowers are in two series — the outer phyllaries are of variable length but narrow, curly, and green; the inner phyllaries are almond shaped, as wide as the petals, and pale yellow-green.

Bidens

Bidens cernua

nodding bur-marigold [Blooms: Aug-Oct]

The flowers of devil's beggars-tick consist only of disc florets. The base of the flower is surrounded by 6-10 (usually eight) long phyllaries that extend beyond the flower's edge.

Bidens

Bidens frondosa

devil's beggar-tick [Blooms: Aug-Oct]

Top — Crowned beggar-tick's (Bidens trichosperma) flowers in frontal view. Bottom — about twelve narrow, twisted phyllaries lie below the yellow flower sepals at the top of the stem.

Bidens

Bidens trichosperma

crowned beggar-tick [Blooms: Sep-Oct]

Hairy wood mint flowers consist of (from back to front) a tubular, stubby calyx with five long teeth and margins with very long, soft white hairs; a white or light purple tubular corolla with an unlobed upper lip, hairy on the outer surface; and a three lobed lower lip with scattered purple dots. Two stamens and a pistil with a bifurcated stigma protrude. Upper right — an ant for scale on a hairy wood mint flower.

Blephilia

Blephilia hirsuta

hairy wood mint [Blooms: Jun-Aug]

Individual flowerheads of false boneset are about a half inch long and surrounded by green phyllaries. Each floret (inset) consists of 7-21 creamy-white, tubular florets with five lobes at the tip, and a prominent divided style protruding from the corolla.

Brickellia

Brickellia eupatorioides

false boneset [Blooms: Jul-Aug]

Butterfly-bush has flowers in a elongate cluster (panicle); each flower is trumpet-shaped with an orange center, and the flared end is split into four lobes.

Buddleja

Buddleja davidii

butterfly-bush [Blooms: Aug-Sep]

American searocket's flowers are 3/8" across with four green sepals, four widely spread pale lavender to white petals, six stamens, and a pistil with a single white style.

Cakile

Cakile edentula

American searocket [Blooms: Jun-Aug]

Purple poppy-mallow has hairy flower pedicels ~6" long that arise from leaf axils; the flowers are ~2" across, brilliant magenta, with an hibiscus-like (but shorter) white central structure containing the stamens and styles. The five calyx lobes are very hairy, shorter than the petals, and light green; beneath the calyx are three very similar bracts.

Callirhoe

Callirhoe involucrata

purple poppy-mallow [Blooms: ?-Jul]