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Purpletop vervain flowers occur in dense, flat-topped clusters 1-3" across. Individual flowers are about 1/4" (5-6 mm) long and 8-9 mm long. The flowers contain a short, tubular, hairy calyx with five teeth; a pinkish purple, tubular corolla with five spreading lobes that have notched tips; four stamens which do not extend beyond the throat of the flower; and a pistil with a single style. The fruit is four nutlets, cupped in the remnants of the calyx as they mature.

Verbena

Verbena bonariensis

purpletop vervain [Blooms: Sept]

Prostrate vervain stems produce dense spikes of flowers at their tips. Beneath each flower is a 3/4" long, narrow bract with long, whitish hairs; the bracts make up the erect or sprawling flower spike (6" long, 3/4" across), with blooming flowers at the tip and fruits maturing below. Individual flowers are about 1/8" across, with a narrow, very hairy, basal calyx extending into five sharply pointed lobes, and a narrow, tubular corolla that abruptly flares into five rounded lobes ("petals") surrounding a white or greenish-white throat; the upper two lobes are slightly smaller than the lower three. Both the calyx and corolla are the same color whether light blue, purple, or pink. Hidden in the throat of the corolla are four stamens with yellow anthers and a short style. The fruit consists of a capsule containing four nutlets that is nestled in the remains of the calyx. This plant is a pioneer in highly degraded habitats that is especially fond of cracks and crevices — despite its weedy appearance, prostrate vervain is a native species. In spite of the tiny size of its anatomical characters, this is a relatively straightforward plant to confidently identify from the hairy stems, leaves, and flower spikes and the tiny, lavender apical flowers.

Verbena

Verbena bracteata

prostrate vervain [Blooms: Jun-Aug]

Flower spikes about 5" long cover the top of the blue vervain plants; they are densely covered with floral buds and flowers that bloom from the bottom of the spikes sequentially to the top. Below the open flowers are maturing fruits. Individual flowers are tubular, 1/4" long and across, with a grayish green to dark red, hairy calyx sporting five narrow teeth; a tubular, purplish-blue corolla twice the length of the calyx that abruptly flares into five equal, ovate lobes ("petals"); four recessed stamens; and a single, short style. The throat of the flower is "bearded" (occluded by light blue filaments extending to the middle of the opening) which hides the reproductive organs. This is the only vervain with a blue (not deep violet/lavender) color; other species are pink, white, or lavender. The fruit consists of four 2 mm long nutlets held in the remnants of the calyx. Blue vervain might be confused with hoary vervain, but the latter has larger (2x), lavender (not purplish-blue) flowers (with one lobe/petal notched and two larger than the other three), and ovate to egg-shaped (not lance-shaped) leaves that are sessile (not on petioles 1/2" long or longer). Blue vervain is especially common along the margins of the lagoons of Jackson Park.

Verbena

Verbena hastata

blue vervain [Blooms: Jul-Sep]

Hoary vervain flower spikes are 1-8" long; they are crowded with buds and bluish violet to lavender flowers 1/2" across that open sequentially from the bottom of the spike to the top; below the open flowers are maturing fruits. Individual flowers are tubular, 1/2" long and across, with a grayish green to reddish-purple, hairy calyx sporting five narrow teeth. The tubular, bluish violet to lavender corolla, twice the length of the calyx, abruptly flares into five ovate lobes ("petals"); the two lateral lobes are the largest, while the lower lobe(s) has/have a notched tip. Hidden in the tubular corolla are four recessed stamens with yellow anthers and a single, short green style. The fruits consist of four nutlets held in the remnants of the calyx.

Verbena

Verbena stricta

hoary vervain [Blooms: Jun-Jul]

White vervain produces numerous 6" long, widely spaced flower spikes, each covered by tiny (1/8" wide) white flowers sparsely distributed along the length of the flower spike. Individual flowers consist of a hairy, tubular green calyx with five lance-like teeth and a curved, tubular corolla that abruptly flares into five short, rounded, brilliant-white lobes ("petals"). The throat of the flower is "bearded" (occluded by white filaments extending to the middle of the opening), hiding four stamens with greenish anthers, a green style, and a two-lobed stigma. The upper (more apical) two lobes of the corolla are slightly smaller than the other three (like prostrate vervain) and the tip of the lowermost lobe of the corolla is notched (like hoary vervain), but you're not likely to confuse white vervain with any other Verbena. The fruit is four oblong nutlets nestled in the remnants of the calyx.

Verbena

Verbena urticifolia

white vervain [Blooms: Jun-Sep]

The tip of a smooth ironweed central stem bears a cluster (a corymb) up to 4" in diameter of magenta composite flowerheads that is quite densely packed in a flat or (sometimes) domed inflorescence. The branches of the inflorescence (but not the stem) may be lightly fuzzy with small hairs. Each flowerhead is 3/4" across and contains 10-30 magenta disk florets, each with five lobes and a very prominent, divided style with curled tips (the stigmas) and five stamens appressed to the base of the style; ray florets are completely absent. The bracts that cover the underside of the flowerheads are green or purplish brown, flattened, appressed, and rounded at their tips, imbricated like fish scales with white, cobwebby hairs around their edges. The fruit is a naked seed with an attached tuft of white hairs (actually, scales). To sort out the Jackson Park ironweeds: (1) if both leaves and stem are densely covered with fine white hairs, the leaves are about 3-4 times longer than wide, and each flowerhead has more than 30 disk florets, it's Missouri ironweed (V. missurica). (2) If both leaves and stems are hairless, there are less than 30 disk florets, and the leaves are narrow (typically a half inch or less; about 6-10+ times longer than wide), it's smooth ironweed (V. fasiculata). (3) If the stems and leaves have only short hairs, there are less than 30 disk florets, and the leaves are about 2" wide and 4-6 times longer than wide, it's tall ironweed (V. gigantea).

Vernonia

Vernonia fasciculata

smooth ironweed [Blooms: Jun-Sep]

Tall ironweed's inflorescence is a flat-topped panicle arising from the tip of the central stem; it is 6-16" across, open and spreading. There are 10-30 disk florets in a tall ironweed flowerhead. The base of the flowerhead is covered by several series of dark colored, broadly oval appressed bracts (phyllaries), often with fine hairs around their edges. The disk florets have tubular, trumpet-like corollas with five recurved lobes; ray florets are absent. Tall ironweed has a much more "open" composite flowerhead than the other ironweeds in Jackson Park, with the trumpet bases of the disk florets easily visible. The fruits are naked, gray or brown, bullet-shaped seeds with a tuft of both short and long tawny or pale purple hairs. To sort out the Jackson Park ironweeds: (1) if both leaves and stem are densely covered with fine white hairs, the leaves are about 3-4 times longer than wide, and each flowerhead has more than 30 disk florets, it's Missouri ironweed (V. missurica). (2) If both leaves and stems are hairless, there are less than 30 disk florets, and the leaves are narrow (typically a half inch or less; about 6-10+ times longer than wide), it's smooth ironweed (V. fasiculata). (3) If the stems and leaves have only short hairs, there are less than 30 disk florets, and the leaves are about 2" wide and 4-6 times longer than wide, it's tall ironweed (V. gigantea).

Vernonia

Vernonia gigantea

tall ironweed [Blooms: Jul-?]

At the tip of a Missouri ironweed stem, a corymb of composite flowerheads (the inflorescence) is produced. The stems of the inflorescence are also covered in fine white hairs and usually reddish brown in color. Individual flowerheads are magenta and rayless; ray florets are completely absent. Flowerheads contain 32-60 disk florets, each 1/2-3/4" across, which have rounded or broadly angled bracts (phyllaries) with sharp tips, dull green or reddish brown in color, that are layered like fish scales around the base. To sort out the Jackson Park ironweeds: (1) if both leaves and stem are densely covered with fine white hairs, the leaves are about 3-4 times longer than wide, and each flowerhead has more than 30 disk florets, it's Missouri ironweed (V. missurica). (2) If both leaves and stems are hairless, there are less than 30 disk florets, and the leaves are narrow (typically a half inch or less; about 6-10+ times longer than wide), it's smooth ironweed (V. fasiculata). (3) If the stems and leaves have only short hairs, there are less than 30 disk florets, and the leaves are about 2" wide and 4-6 times longer than wide, it's tall ironweed (V. gigantea).

Vernonia

Vernonia missurica

Missouri ironweed [Blooms: Jul-Oct]

At the top of the Culver's root plant are floral spikes (racemes) up to 10" long covered with small (1/4" long) white, tubular flowers. Individual flowers consist of a short (3 mm long), green calyx with five deep lobes (the lower two lobes longer than the upper three); a tubular corolla with four lobes (the lower two longer than the upper two); two stamens with yellow or reddish brown anthers; and a single style with a tiny stigma. The stamens and stigma protrude well beyond the lip of the flower. The flowers bloom from the base of the floral spike successively towards the tip. The fruit is a 2.5-4.5 mm long ovoid capsule with four apical teeth. The capsules contain 10-30 half millimeter long, ovoid seeds. Culver's root is very popular with a wide diversity of bees.

Veronicastrum

Veronicastrum virginicum

Culver's root [Blooms: Jun-Aug]

Korean spice viburnum's inflorescences are 2.5" diameter umbels of flowers on the tips of new twigs. The flowers are aromatic; the scent is described by the Chicago Botanic Garden as "sweet, rich, and complex with a hint of cloves." The flowers are fragrant for only about two weeks. Individual flowers consist of a tiny (1 mm long), reddish green calyx with five lobes; 8-10 mm long tubular, pale pink to white corollas with five abruptly spreading lobes; five stamens with yellow anthers just inside the throat; and a short (1 mm long), stout style with a knob-like stigma. The corolla is about 1/2" across. Korean spice viburnum flowers are superficially similar to butterfly-bush (Buddleja davidii), which also occurs in Jackson Park, but the latter has a spike-like inflorescence rather than an umbel.

Viburnum

Viburnum carlesii

Korean spice viburnum [Blooms: Apr]

Yellow violet is a native perennial, the only yellow violet species in Jackson Park (indeed, in all of Illinois). One or more stems arise from an axil of a stem leaf; they are up to 6" tall with a single 3/4" long flower at their tips. Each flower consists of five light green sepals, five yellow petals, five stamens, and a single style; the stamens and style cannot be seen from the exterior. On the lower petal, the flowers have purple lines (nectar guides) and a spur reduced to a small pouch. The two lower, lateral petals have small tufts of hair that obscure the throat of the flower and hide the stamens and style; the two upper, lateral petals are beardless and have only faint lines (nectar guides), if any. The fruit of this species is a bullet-shaped (hairless in the Jackson Park forms) capsule nestled in the calyx with the remnant of the style at its tip, initially green but turning brown as it matures; it ultimately splits along three suture lines to fling the seeds away from the plant.

Viola

Viola pubescens

yellow violet [Blooms: Apr-May]

Common blue violet flowers are 3/4-1" across with the calyx formed from five elongate oval, dark green sepals with a pointed tip, five petals (two upper, two lateral petals with white hairs ("beards") that occlude the throat of the flower, and one lower petal with a white patch and superimposed dark blue lines near the throat). The lower petal has a pouch (the "spur") that extends backwards past the base of the sepals; the spur houses the ovary, single style, and stigma (positioned just behind the petal beards) and, more posteriorly, the nectary. The two stamens surround the ovary and can't be seen without dissecting the flower. Flower color may range from deep violet to white with a purple center, all fading to pale yellow in the center. The fruit is a bullet-shaped capsule 1/4-1/2" long that is nestled in the calyx with the remnant of the style at its tip, initially green but turning brown as it matures; it ultimately splits along three suture lines to fling the approximately 75 seeds, beige or bronze in color, 1.5-2.5 mm long, away from the plant. Much of the reproduction occurs from vegetative clones produced from the rhizomes. Common blue violet prefers light sun or partial shade and a rich soil.

Viola

Viola sororia

common blue violet [Blooms: Apr-May]