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The flowers of devil's beggars-tick consist only of disc florets. The base of the flowerhead 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]

In black mustard, racemes of yellow flowers arise from the tip of the stems, with the siliques (fruit) of previously fertilized flowers arrayed along the stem below the flowers. The racemes of flowers are 1/2-2" long. Each flower is about 1/3" (8 mm) across, consisting of a short (2-4 mm) pedicel, 4 sepals (green in the buds, turning yellow after the flower opens), 4 yellow, oval to round petals with a narrow base ("claw"), 6 greenish-yellow stamens with yellow anthers, and a green ovary with a short style (which persists in the siliques) at its apex. Fertilized flowers produce smooth, elongate fruits (siliques) 2-3 mm across, approximately four-angled in section, and 1/2-1" long, tapering to a conical or cylindrical beak with the remnant of the style at its tip. The siliques contain 4-15 seeds and are often closely appressed to the stem. The seeds are dark brown or black with networks of furrows on their surface.

Brassica

Brassica nigra

black mustard [Blooms: Jun-Jul]

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]

The flowers of hedge bindweed are 2-3" long, formed from five white or pink fused petals; the throat of the trumpet is light yellow (less extensive than in field bindweed). The flowers are ephemeral, often lasting only a single day.

Calystegia

Calystegia sepium

hedge bindweed [Blooms: May-Sep]

Wild hyacinth flowers have six slender, light blue to white tepals, six stamens with yellow anthers, and a slender style emerging from a green, egg-shaped ovary; the style has tripartite tip. The flowers are each supported by a slender pedicel. Wild hyacinth is very similar to prairie hyacinth (Camassia angusta), but the latter blooms later, is much less common, has thread-like bracts beneath each flower pedicel, 4-5 thread-like bracts on the flower stalk beneath the flowers, and differ (mostly) in details of the seed capsule. Prairie hyacinth has not yet been found in Jackson Park.

Camassia

Camassia scilloides

wild hyacinth [Blooms: May-Jun]

American bellflower has deep blue flowers with a white center; they are about 1" across. The petals are ruffled, the style is long, arching, with a trifid stigma on its tip.

Campanula

Campanula americana

American bellflower [Blooms: Jul-Aug]

Creeping bellflower stems produce a terminal raceme of blue to purple flowers up to a foot long with all the flowers nodding towards the ground and all on the same side of the stem. Individual flowers are 1-1.5" long, borne on a short pedicel with a narrow, lance-shaped bract at its base. Each flower is bell-shaped with five pointed, recurved lobes with hairy margins and five green sepals at its base. There are 5 short curly, yellow stamens and a long style that emerges from the bell; the style has a three-part stigma at its end.

Campanula

Campanula rapunculoides

creeping bellflower [Blooms: Aug-Sep]

Shepard's purse flowers bloom only at the stem's tip, which is continually elongating. Individual flowers are tiny (1/8") and have 4 greenish sepals, 4 rounded white petals, 6 greenish-yellow stamens, and a pistil with a single style. Flowers are followed by seedpods ("purses") that are 1/4" long, triangular, or heart-shaped, borne on ascending pedicels (lower part of image.)

Capsella

Capsella bursa-pastoris

shepard's purse [Blooms: Apr-May]

Cutleaf toothwort's flowers are ~1/2" across when fully open; the flowers arise from a slender pedicel as long as the flower, 4 green or purple bluntly-pointed sepals <1/3 the length of the petals, four lavender-white petals, six stamens with yellow anthers, and a single pistil with a flat, discoid stigma.

Cardamine

Cardamine concatenata

cutleaf toothwort [Blooms: Apr-May]

Hairy bittercress flower stalks with stem leaves. Here the three flowers bear seedpods (siliques - narrow cylinders) that elongate directly out of fertilized flowers (which continue bear petals).

Cardamine

Cardamine hirsuta

hairy bitter-cress [Blooms: April]

Pennsylvania bittercress flowers are 1/8" across with 4 light green, oblong sepals that cup the corolla, 4 white petals, 6 cream-colored stamens, and a single robust pistil with a flat, disc-shaped stigma. Fruits are erect, elongate (up to 1.25" long and 1 mm wide), flat-ended cylinders (siliques) containing a single row of seeds that emerge from the center of a fertilized flower while the petals persist.

Cardamine

Cardamine pensylvanica

Pennsylvania bitter-cress [Blooms: April]

Nodding thistle is another heavily-defended exotic thistle, accidentally introduced to the U.S in the early 1900s. Solitary flowerheads are borne on long (up to 2'), whitish peduncles densely covered with short hairs. The flowerheads are 1-3" across, nodding (like the name says), made of 100-1000 tubular disk florets, each with its apical portion divided into 5 purplish-pink filaments and with a single, very long style. Beneath the large, showy flowerheads are stout, triangular, purplish phyllaries, each with a stout spine. When in bloom, the large size of the flowers and characteristic large phyllaries make it impossible to confuse with any of our other local thistles. Well loved by goldfinches, but considered a "noxious weed" by almost everyone else.

Carduus

Carduus nutans

nodding thistle [Blooms: Jun-Jul]

Inflorescences of woodland sedge occur as a terminal staminate (male) spike 6-12 mm long and 2-4 ovoid pistillate (female) spikelets 10-20 mm long and 5 mm wide that are lower on the culm. The proximal urn-shaped structures on the inflorescence (and in the inset) with the two fuzzy filaments are the pistillate spikelets; the distal structures with the terminal yellow rods in the image are the staminate spikelets. (Cylindrical clusters of florets are called spikes; ovoid clusters are termed spikelets. Individual sedge flowers — a perigynium or utricle — are usually ovoid, with either 2-3 feathery stigmas or three stamens with anthers sticking out of one end. Bisexual flowers do not occur in sedges.)

Carex

Carex blanda

woodland sedge [Blooms: Apr-May]