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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]

In corn speedwell, single flowers 1/8" wide develop at the tips of inflorescences that arise from the axils of the middle and upper leaves; the flowers are nearly sessile. The inflorescence continually elongates, producing new flowers and a series of bracts along its length. The most basal bracts resemble the stem leaf whose axil hosts the inflorescence; the upper bracts are alternate, 3-10 mm long, and narrowly lance-shaped with long hairs fringing the bract margins. Each flower consists of four hairy, green, lance-like sepals/bracts longer than the corolla lobes; a blue to blue-violet corolla with four petal-like lobes, the upper three lobes slightly larger than the lower forth lobe; two stamens with white anthers; and a pistil with a single style. Dark lines (nectar guides) radiate from the throat of the corolla. Each flower only lasts a single day. The fruit is a 1/8" long and wide, tan, heart-shaped seed capsule, somewhat flattened, with two compartments containing 10-30 yellowish, ovoid seeds. There are 16 species of the genus Veronica reported from Illinois. I have only seen three (Veronica arvensis, Veronica polita, and Veronica serpyllifolia) in Jackson Park but, given their minute size and inconspicuousness, it seems likely that more remain to be found.

Veronica

Veronica arvensis

corn speedwell [Blooms: Apr-Jun]

Wayside speedwell's flowers are 1/4" across with a green, hairy calyx with four triangular lobes as long as the petals, projecting between them in the spaces between petals; a short corolla with four spreading lobes, three the same size (one on either side, blue to bluish-white with dark blue lines, and the third dark blue with blue-violet lines) and one about half as wide, pale blue or white with light blue lines. The blue lines function as nectar guides. The base of all four lobes is bright white, but the center of the flower is greenish. There are two white stamens with white anthers (backed by a dark blue "U" shape) and a single white pistil emerging from the throat of the corolla. The fruits are heart-shaped capsules with two chambers covered with glandular hairs, each containing 8-12 seeds. The flowers and leaves of wayside speedwell are similar to those of bird's-eye speedwell (Veronica persica), but the calyx lobes of bird's-eye speedwell do not project beyond the petals. There are 16 species of the genus Veronica reported from Illinois. I have only seen three (Veronica arvensis, Veronica polita, and Veronica serpyllifolia) in Jackson Park but, given their minute size and inconspicuousness, it seems likely that more remain to be found.

Veronica

Veronica polita

wayside speedwell [Blooms: Apr-Jun]

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]

American wisteria's flowers occur in showy terminal racemes. The flowers have 1/2" long pedicels that are densely covered with stiff hairs and some club-shaped, stalked glands. Individual flowers consist of a 1/4-3/8"white to pale green, hairy calyx and 15-20 mm long bluish-purple, pea-like, hairless flowers. The expanded portion of the banner (or standard) is bent backwards so it is perpendicular to the axis of the rest of the flower; the two lateral petals cover the keel like a hood. There are 10 stamens with tiny anthers, an ovary encircled by a nectar gland, and a single style hidden within the keel; nine of the 10 stamens are fused to each other, the tenth is free. The fruits are 2.75-4" long pea-like, hairless green pods containing 4-8 kidney-shaped or oval seeds, each about 8 mm wide; the pods are brown and the seeds are black when mature. The seeds contain an alpha-amino acid called canavanine which is structurally similar to L-arginine and the pods contain a saponin called wisterin; neither is a good thing to ingest. I've only seen American wisteria growing on the fence west of Japanese Garden. Periodically, the Park District cuts it down, I suspect because they fear for the fence's structural integrity (it's a heavy plant), but I wish a better solution could be found given American wisteria's rarity.

Wisteria

Wisteria frutescens

American wisteria [Blooms: May-Oct]