Culver's Root is a native erect perennial, an easy to spot plant, it grows up to seven feet in height, with round, green to dark green, smooth or slightly hairy stems, sometimes branching near the top.
Leaves are in whorls of 3 to 7 with the whorls widely spaced on the stem. They are dark green, oblong to ovate with fine teeth on the margins and taper to a short stalk. The veins are prominent with a mid-rib and curving lateral veins; the top side is usually hairless, the underside is much paler in color and can have fine hair especially on the ribs.
The inflorescence is a dense spike atop the stem. All but the most immature plants will have several smaller flower spikes rising from the stem below the central spike, which is the first to develop.
The flowers are small, 4-parted, about 1/4 to 1/3 inch long, tubular shaped with a white corolla whose lips spread slightly. The lips are much shorter than the corolla tube, with the upper lip having one lobe and the lower lip with 3 lobes. From the tube protrude two stamens that have white filaments and deep yellow to brown anthers. Also protruding is a single white style. The calyx is green, short with pointed lobes (sepals).
Seed: Pollination is mostly by long and short tongued bees. Fertile flowers produce a seed capsule that is longer than the calyx. The small, dry, brown, ellipsoid shaped seeds are not easily detached from the capsule as it does not split open very far at the top, and thus end up on the ground still inside the capsule. Seeds can germinate without a waiting period in warm and moist conditions. They are very small and need light for germination. If stored, storage should be in cold dry conditions.
Toxicity: The root is toxic - see notes at bottom of page.
Habitat: Culver's Root tolerates most soils, but grows best in sandy or loamy soil, moist to dry, with full sun to partial shade. It grows from a taproot and small slender rhizomes which are nearly cylindrical and dark brown on the outside of older ones (hence the name "Black root"). The rhizomes allow it to spread vegetatively and divisions of these is the best way to propagate the plant. The plant will usually be found in clumps. The flower stems are good for cutting. Besides the native white color, there are several cultivars available in the nursery trade that have other colored flowers. The plant can make an excellent back border specimen in the home garden. A single stem plant can by the third year provide a clump of 8 to 12 stems. The species is subject to a root borer pest - notes below.
Names: The scientific name is derived as follows: "Veronicastrum" is derived from two words - 'Veronica' - the name for the Speedwell plants which were supposedly named for St. Veronica, and 'astrum', meaning 'an incomplete resemblance' - hence a plant that resembles somewhat the Speedwells; the species "virginicum" - means 'of Virginia' - where the plant was originally collected. It was formerly classified by Thomas Nuttall as Leptandra virginica and prior to that it was placed by Linnaeus (the 'L' in the scientific name) in the genus Veronica, where in Eloise Butler's time it was known as Veronica virginica. Veronica is not the same as Veronicastrum. The current author name for the plant classification, ‘Farw.’ is for Oliver Atkins Farwell (1867-1944) American Botanist. Botanists have recently moved this genus and the Veronicas into the plant family Plantaginaceae, removing it from Figwort (Scrophulariaceae). The common name refers to a Dr. Culver, an 18th Century American physician, who promoted the use of the plant. (See lore below.)
Above: First blooms will appear in early July, with main display in late July and continuing into August.
Below: Flowers are about 1/4 to 1/3 inch long, tubular shaped with a white corolla whose lips spread slightly. The lips are much shorter than the corolla tube, with the upper lip having one lobe and the lower lip with 3 lobes. Stamens and style protude.
Below: 1st photo - A typical leaf whorl, this one with 5 leaves. Note the fine hair on the stem which some plants may have. 2nd photo - A single leaf - note the defined vein pattern with a prominent central rib and the fine teeth on the margins.
Below: 1st photo - The underside of the leaf is paler in color and can have fine hair, especially on the ribs. 2nd photo - Root of a young plant. The rhizomes are long and slender, turning dark with age.
Below: The mature seed capsules only open a little at the tip and the brown ellipsoid seeds do not shake out easily. Each capsule contains numerous seeds.
Notes: This plant is indigenous to the Garden area. Eloise Butler catalogued it on Sept. 6, 1907. She obtained additional plants in 1911. Cary George noted planting it in 1995. It is native throughout Minnesota except in counties that are west central, north central and Cook. It is widely found in the eastern half of North America, east of a line running from Manitoba to Texas. It is on a "threatened" list in several New England States. This is the only species of Veronicastrum found in Minnesota.
Toxicity: The fresh root is a violent cathartic (a purgative) and is dangerous to use as it may produce bloody stool and possibly abortion. The dried root is much milder and is the accepted procedure.
Culver's Root Borer: The moth Papaipema sciata is an infrequent pest of the plant, laying its eggs on or near the plant in late fall. The larvae from the eggs bore into the lower stem the following year and enter the root causing the plant to wilt and die. Details about this pest are found in this 2004 paper from the University of Michigan.
Lore and Medicinal Uses: A decoction of the root from the plant was known to early medical practitioners as a powerful laxative and emetic (produces vomiting). For this purpose the root was boiled in milk or steeped in hot water. The Seneca Indians induced vomiting by drinking a tea made from the dried root. Densmore (Ref. #5) reports the Chippewa used it as a blood cleanser. The Chippewa name is wi'sûgidji'bĭ, which means "bitter root". (Older reports such as Densmore use the older scientific name "Leptandra virginica".) A decoction was made from the roots. It has attributed to it the ability to increase the flow of bile from the liver, (see below) therefore herbalists often employed dried root in treatment for liver disorders and chronic indigestion. It’s first recorded use in North America was in 1716 when Cotton Mather sought a remedy for his daughter’s tuberculosis and asked for the plant. This was a pretty violent drug to use for a lung ailment and she died soon thereafter.
Because of it's known medicinal uses it was listed in the National Formulary 4. Both the rhizome and the roots are "cholagogue" (Gastrointestinal agents that stimulate the flow of bile into the duodenum) and cathartic (purgative). Mrs. Grieve (Ref. #7) reports (and also partially in Densmore) that Culver's root is known to contain volatile oil, cinnamic acid derivatives, gum, resin, a crystalline principle, a saccharine principle, tannic acid, and a glucoside. A bitter principle called "leptandrin" is obtained from a tincture of the root. Leptandrin excites the liver gently and promotes the secretion of bile without irritating the bowels. It is also a tonic for the stomach. The decoction was made by combining 1 oz of Culver’s Root, 2 oz of Golden Seal (Hydrastis canadensis), 2 oz of Senna (Cassia marilandica) and 2 pints of boiled or distilled water, then boiling it until reduced to 1 pint. The dose was to take 2 tablespoonfuls three or four times per day. (Ref. #12)
Eloise Butler wrote of this plant: "To subdue the brilliant orange and reds of the lilies and composites, Mother Nature has planted among them with judicious and generous hand various white flowers, as Veronica virginica, (the old botanical name) with feathery spires of bloom, some branched like candelabras, topping slender stems, clothed at intervals with whorls of narrow, pointed leaves. It is popularly called Culver’s Root, or Culver’s Physic, because one of that name extracted a specific from the root." Published in the Minneapolis Sunday Tribune July 16, 1911.
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"