White Vervain is an erect native forb that can be annual, biennial or a short-lived perennial. It grows from 1.5 to 6 feet tall on 4-sided slender stems that may branch in the upper half. Stems are usually covered with spreading hair.
The leaves are opposite, lance-like to ovate, with coarse teeth, sometimes with double teeth, tips are pointed, and the base tapers to a short grooved stalk, except the small upper leaves which can be stalkless. The upper surface is dark green with prominent main veins and a net-like pattern of smaller veins.
The inflorescence is a collection of loosely (some would say 'wildly') spreading branched spikes forming a panicle that is half as broad as tall. The branches of the panicle are ascending and there can be small axiliary spikes from the upper leaf axils.
The flowers are very small 5-parted and stalkless, arranged along the spikes, with only a few open at one time. The corollas are usually white as the common name implies, but may shade to blue or pale purple. The corolla has 5 rounded lobes, the calyx is green, hairy, with 5 teeth (lobes) and subtended by a pointed green bract that is shorter than the calyx lobes. There are 4 short stamens arranged in pairs of unequal length. The style is green and short.
Seed: Mature flowers produce an oblong 4-chambered capsule that contains 4 brown oblong nutlets with somewhat squared off sides, which fall from wind action soon after maturing. Seeds are about 1.5mm long and the entire capsule is only 2mm long plus a short stalk. Verbena seeds require a short period of cold stratification for germination.
Habitat: White Vervain grows in full sun in moist thickets, wood edges and disturbed areas.
Names: Mrs. Grieve (Ref. #7) states that the name vervain is also derived from the Celtic ferfaen, that is from fer (to drive away) and from faen (a stone). In early times the plant was used for afflictions of the bladder, such as kidney stones. Verbena was the Roman name for altar plants in general and in particular V. officinalis. The species name, urticifolia, means have nettle-like leaves, referring to their resemblance to those of the Nettle genus - example Urtica dioica. The author name for the plant classification - 'L.' refers to Carl Linnaeus (1707-1778), Swedish botanist and the developer of the binomial nomenclature of modern taxonomy.
Comparisons: White Vervain slightly resembles the Blue Vervain, V. hastata. There however, the flowers are always blue, the inflorescence is upright and not loosely spreading and the leaves have an outward facing basal lobe.
Above: Photo - The inflorescence. Drawing from Britton, N.L., and A. Brown. 1913. An illustrated flora of the northern United States, Canada and the British Possessions. 3 vols. Charles Scribner's Sons, New York.
Below: 1st photo - Arranged along each spike are the stalkless flowers, with only a few open at at a time. 2nd photo - Stems are 4-angled, and leaf stalks and stem are covered with fine spreading hairs. 3rd photo - the leaf underside is paler in color due to minute whiteish hair with longer hairs on the main ribs.
Below: The lower stem leaves are opposite, lance-like to ovate, with coarse teeth, sometimes with double teeth, tips are pointed, and the base tapers to a short grooved stalk. The upper surface is dark green with prominent main veins and a net-like pattern of smaller veins.
Below: Another view of the flowering panicle which is a collection of loosely spreading branched spikes.
Below: 1st photo - The corollas are usually white as the common name implies, but may shade to blue or pale purple. The corolla has 5 rounded lobes, the calyx is green with 5 teeth with ovate bracts beneath that are shorter. 2nd photo - Seeds are oblong, 4-angled and brown at maturity separating from a 4-chambered capsule.
Notes: White Vervain is indigenous to the Garden; Eloise Butler catalogued it on Sept. 6, 1907. Martha Crone planted it in 1953. It is found in North America from the Great Plains eastward, except for the maritime provinces of Canada. In Minnesota it is found in many counties throughout the state except for the NE section and other widely scattered counties.
There are 5 Verbenas found today in Minnesota, 4 native and 1 introduction. Also 3 other species that are known historically only, with some question as to whether they ever were found here. The extant Verbenas are: V. hastata, Blue or Swamp Vervain; V. simplex, Narrow-leaved Vervain; V. stricta, Hoary Vervain; V. urticifolia, White Vervain; and V. bracteata, Large-bracted Vervain. The latter is the introduction. V. simplex is on the state's Special Concern List.
References: Plant characteristics are generally from sources 1A, 32, W2, W3, W7 & W8 plus others as specifically applied. Distribution principally from W1, W2 and 28C. Planting history generally from 1, 4 & 4a. Other sources by specific reference. See Reference List for details.
Identification booklet for most of the flowering forbs and small flowering shrubs of the Eloise Butler Wildflower Garden. Details Here.
Friends of the Wild Flower Garden, Inc. Text and photos are by G. D. Bebeau unless otherwise credited. "www.friendsofthewildflowergarden.org"