Verbena urticifolia L.

White Vervain

© SRTurner

Family - Verbenaceae

Habit - Perennial forb from a woody caudex.

Stems - Strongly ascending to erect, to 2.0 m, 4-angled,, hollow, single or multiple from base, simple or branching, moderately pubescent with nonglandular, straight or somewhat curved, spreading, sometimes pustular-based hairs, often with shorter, ascending hairs toward the tip.

	Stem and node.
© DETenaglia

Leaves - Opposite, simple, petiolate. Petioles to 3 cm long, winged by decurrent leaf tissue. Blades 5-12 cm long, at least those of the largest leaves 20-70 mm wide, broadly lanceolate to ovate, rounded or short-tapered to a nonclasping base, tapered to a sharply pointed tip, unlobed, the margins relatively coarsely and sometimes doubly toothed, both surfaces glabrous to moderately pubescent with spreading to loosely appressed, nonglandular, sometimes pustular-based hairs, deep green above, light green below. Veins impressed on adaxial surface, expressed on abaxial surface.

	Leaf adaxial.
© SRTurner

	Leaf abaxial.
© SRTurner

	Leaf abaxial surface.
© SRTurner

	Pressed leaves.
© DETenaglia

Inflorescence - Broad panicles of numerous spikes, these 8-50 cm long, relatively open (the flowers not overlapping), slender, elongating greatly with age. Bracts 0.5-1.5 mm long, shorter than the calyx, ovate to narrowly ovate.

	Inflorescence.
© SRTurner

Flowers - Calyces 5-lobed, pubescent externally, 1.5-2.5 mm long, the lobes triangular, acute. Corolla white, 5-lobed (weakly bilabiate with one notched upper lobe and 3 bottom lobes), 2.5mm broad. Corollas 2-4 mm long, the outer surface sparsely to moderately hairy, especially toward the tip of the tube, funnelform, white, the tube to 3 mm long, pubescent externally, bearded internally, relatively slender, the limb 1-2 mm in diameter. Stamens 4, didynamous, included. Filaments very short. Anthers greenish. Ovary superior, green, glabrous, 0.5 mm long, cylindric. Style green, glabrous, with a lateral appendage. Stigma capitate.

	Calyces.
© DETenaglia

	Flowers.
© SRTurner

	Flowers.
© DETenaglia

Fruits - Nutlets 1.5-2.0 mm long, oblong to narrowly oblong or oblong-elliptic in outline, the inner surface usually slightly pale and smooth or with sparse to moderate, minute papillae, the outer surface yellowish brown to reddish brown, smooth or with several longitudinal ridges, these sometimes with a few crossridges toward the tip.

	Fruits.
© SRTurner

Flowering - June - October.

Habitat - Streambanks, pond margins, forest openings, savannas, pastures, fields, fencerows, railroads, roadsides, open disturbed areas.

Origin - Native to the U.S.

Lookalikes - None.

Other info. - This common plant is found more or less throughout Missouri and the eastern half of the continental U.S. The plant is easily identified by its tiny white flowers and open inflorescences with long, skinny branches. The specific epithet urticifolia means "nettle leaved."

Photographs taken in the Ozark Scenic Riverways, Shannon County, MO., 6-22-04 (DETenaglia); also at Marais Temps Clair Conservation Area, St. Charles County, MO, 7-5-2020, and Young Conservation Area, Jefferson County, MO, 8-17-2020 (SRTurner).