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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]

Wayfaring tree flowers occur in flat-topped cymes about 4" across; they are cream-colored with five petals, five stamens with white filaments and tan anthers, and a green ovary with a short (1 mm) style with a large, lobed stigma. The fruit is an oval, flattened drupe, initially red, turning black with maturity, and containing a single seed. They are not toxic but can induce vomiting it eaten when unripe. Wayfaring tree is said to be so named because it grows close to paths (and presumably other natural edges).

Viburnum

Viburnum lantana

wayfaring tree [Blooms: Apr-May]

Nannyberry flowers occur in 2-5" wide, dome-shaped panicles at the tips of young shoots. Individual flowers are 1/4" across, consisting of a light green calyx with five triangular teeth; a creamy white corolla with five oval lobes; five stamens with white filaments and yellow anthers that protrude well past the edges of the corolla lobes; and a light green or yellow pistil with a short style. The fruit is a 6-10 mm long drupe, initially green but turning dark blue-violet when ripe, containing a single seed. Nannyberry is similar to blackhaw (Viburnum prunifolium, also present in Jackson Park) — both have white flowers and blue-black fruits that are drupes — but nannyberry leaves have a long, narrow tip on their leaves in contrast to the rather blunt tips on blackhaw leaves.

Viburnum

Viburnum lentago

nannyberry [Blooms: Apr-May]

In the spring, American cranberry shrubs produce flattened panicles of flowers 2-5" across that bear two types of flowers — around the edges are five-petaled, white flowers about 1" across that are sterile (lacking both pistils and stamens), while in the center of the cluster are five-petaled, cream-colored flowers 1/4" across that are fertile (with both a pistil and five long stamens). By late summer, the flowers are replaced by bright red "cranberries" (actually drupes with a single seed) 1/4-1/2" across that prove very popular with birds (which distribute the seeds) and our local coyotes (whose scat is full of the seeds). After removing the seed, the tart flesh (high in vitamin C) can be eaten raw or cooked. In the fall, the leaves also turn red. Viburnum opulus var. americanum is said to be distinct from Viburnum trilobum (aka, highbush cranberry) by Illinois Wildflowers (www.illinoiswildflowers.info) and Minnesota Wildflowers (www.minnesotawildflowers.info), but plants.usda.gov insists that the latter is a synonym of the former. Worldfloraonline.org only adds to the confusion by insisting that the two names are BOTH junior synonyms of Viburnum opulus. ITIS.gov says that V. opulus is the correct name for the European species (now introduced to the U.S.) and Viburnum opulus var. americanum is the correct name for the American species. The easiest way to distinguish the two forms (if you care to) is to carefully inspect the nectary glands (extrafloral nectaries) on the petioles. In V. opulus americanum, the extrafloral nectaries are oval, with a concave top and a distinct rim; in Viburnum trilobum, the extrafloral nectaries are round in plan view with a convex top and no rim. Although rare in most of Illinois, guelder-rose (V. opulus americanum) is quite common around the lagoons of Jackson Park.

Viburnum

Viburnum opulus

American cranberry [Blooms: Apr-May]

Cymes of flowers arise from the leaf axils of blackhaw; the cymes are heavily branched but are sessile on the leaf axil. Individual flowers are 1/4" across with a 2 mm long calyx tube with five apical lobes that are shorter than the petals; a tubular corolla with five white, rounded lobes (the "petals"); five stamens with white filaments and yellow anthers extending outside the corolla lobes; and a small (less than 1 mm long), cream-colored pistil. The fruit is a fleshy drupe (like a plum or cherry) about 8 mm long containing a single brown nutlet that is flat on one side; the fruit becomes blue-black as it matures. The fruits are edible and popular with birds. Blackhaw is similar to nannyberry (Viburnum lentago, also found in Jackson Park) — both have white flowers and blue-black fruits that are drupes — but nannyberry leaves have a long, narrow tip on their leaves in contrast to the rather blunt tip and reddish petioles on blackhaw leaves. The stamens in blackhaw flowers are slightly shorter than those in nannyberry flowers but the difference is subtle; leaf form and petiole color are better differentiators.

Viburnum

Viburnum prunifolium

blackhaw [Blooms: May-June]

Many of the upper shoots of downy arrowwood end in 1.5-3" wide, dome-shaped panicles of flowers with slightly fuzzy, light green branches. Individual flowers are 1/4" across with a short, light green calyx with five short, broad teeth; a white tubular corolla with five rounded, spreading lobes; five stamens with white filaments and tan anthers that extend outside the corolla; and a single white style. The flowers have an unpleasant odor described by various sources as "rotting flesh." The fruit is a small (1/4-1/2") drupe (a stone fruit like cherries or a plum) 8 mm long and dark blue-violet to black at maturity. Downy arrowwood can be distinguished from other Viburnum spp. by its (1) its small size (less than six feet tall), (2) the relatively few teeth along the leaf margins (5-10 per side), (3) the short (about 1/4") leaf petioles, (4) the small, narrow stipules at the petiole bases, and (5) its flowers' unpleasant odor. The common name derives from the fact that the straight stems of the various arrowwoods was preferred by indigenous Americans for arrow shafts.

Viburnum

Viburnum rafinesquianum

downy arrowwood [Blooms: Aug–Sep]

Wild pansy's flower stalks are long, hairless, and bend like a shepherd's crook just below the base of the flower so the flower axis is approximately horizontal. Individual flowers have five 7-15 mm long, lance-shaped sepals that are longer than the petals and are sharply pointed at their tips; a 4-12 mm long corolla with five white or pale cream-colored petals, a yellow throat with a few dark purple lines, the lateral petals bearded on their upper surface, and a 1-1.5 mm long spur; two stamens not visible externally; and a single style enlarged into a hollow, globose stigma. The fruit is a spherical or ellipsoidal three-valved capsule, 5-10 mm long containing 6-75, 1.5 mm long, brown seeds.

Viola

Viola arvensis

wild pansy [Blooms: Jun-?]

Common cocklebur produces a spike-like raceme of compound flowerheads, shorter than the leaf petioles, that arises from the axils of each upper leaf and from the tip of the central stem. Each raceme produces exclusively male flowerheads in its upper parts and exclusively female flowerheads in the lower regions. The male flowerheads are about 1/4-3/4" across, elevated on a short pedicel on top of 1-3 series of white floral bracts. Each of the approximately 20 tiny, brownish-green staminate florets (nominally disk florets) consist of a tubular 1-2 mm long corolla; a minute, non-functional ovary; and five stamens with fused filaments (like a tree trunk) but with their white anthers free, positioned in a ring like a little palm tree or, possibly, a hand. The staminate florets quickly shed their pollen and drop off. The female flowerheads (also nominally disk florets) are 3/4-1.5" long and two-thirds as wide, stalkless, each (usually) containing two female florets nearly enclosed by floral bracts covered with curly white hairs that have a bur-like appearance from the dense, hooked prickles covering their surface. At the tip of the flowerhead are two spines, longer and much stouter than the prickles, each with a hole from which protrudes the divided style of a female floret. There is no corolla in the female florets. The florets are wind pollinated, and their styles quickly wither away after fertilization. Each female floret produces a single, oblong, dark gray to black seed 3/8-1/2" long, tapering to a point at each end and covered by dark membranes, all buried in the bur-like bract. The female flowerhead stiffens through the autumn, turns brown, and overwinters. The seeds are highly poisonous, containing toxic diterpene glycosides. One of the contained seeds germinates the following year; the other delays germination for two years. Common cocklebur prefers wet, sandy soils.

Xanthium

Xanthium strumarium

common cocklebur [Blooms: Sep-?]