The group of plants in the genus Prenanthes known as Rattlesnake Roots have clusters of bell shaped flower heads and unlike most species in the Aster family where the flower head is a composite of ray and disc florets, the Prenanthes lack the disc florets.
White Rattlesnake Root is a native erect perennial forb that grows 1 to 5 feet high, usually unbranched; the stem contains a milky juice, stem color is usually purplish but can have a whitish bloom. The root may produce several stems.
Leaves are highly variable in shape at the base of the plant, from ovate to triangular to heart shaped with margins that are coarsely toothed to deeply 3 to 5-lobed. Triangular leaves are sometimes arrow-shaped with lobes at the base. Lower leaves are on long stalks that may have a shallow wing or none at all. The upper surface of the leaves is smooth, the lower surface sometimes with fine hair. Upper stem leaves are alternate, smaller and simpler in shape. Lower leaves are still on the plant at flowering time.
The floral array consists of clusters of 3 to 8 nodding flowers grouped on a short branch from long-stalked upright panicle arrays at the top of the stem and from the upper leaf axils. Each flower has a short stalk. All parts of the panicle are usually without hair.
Flowers: The flower head forms a cylindrical shape about 1 inch long that, before opening, is surrounded by a single series of 8 (6 to 9) long narrow phyllaries, (10 - 13 mm long) that are purplish or maroon in color, with pointed tips. At the base of these is a group of 5 to 7 much shorter bractlets (calyculi), more purplish-green in color, with triangular tips. Each flower head then has 7 to 9+ fertile ray florets with rays that can be whitish to cream or pinkish, occasionally lavender. As the flower head opens, the rays of the florets spread outward, each showing a truncated tip that has minute teeth. Each floret exserts beyond the corolla a long style with a bifurcated tip. The anthers and nectar glands are retained within the the throat of the floret. Flowers have a light scent. There are no disc florets. The flower head base itself is quite short and only 3 to 5 mm wide.
Seed: The deep throat of the flower requires pollination by bees and fertile flowers produce a linear to elliptical shape brownish cypsela, 3.5 to 6 mm long, that has reddish-brown hair pappus attached for wind dispersion. The cypselae require 60 days of cold stratification for germination.
Habitat: White Rattlesnake Root grows from short and thickened taproots. It prefers moderate moisture soils in scrub woods, partially shaded hillsides, dry banks, etc. It prefers partial sun and tolerates shade.
Names: The genus name Prenanthes, is derived from the Greek words prenes, meaning 'drooping' and anthos, meaning 'blossom' thus 'drooping blossom'; the species name alba is Latin for "white." 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: The other three species of Prenanthes found in Minnesota (listed below the photo section) differ as follows: P. aspera (less frequently found) has rough hair on the mid-stem and lower leaves are withered or absent at flowering time, corolla rays are pale yellow to creamy white; P. racemosa has smooth mid-stems, lower leaves persistent and corolla rays are more pinkish; P. crepidinea (known only in Houston County) has toothed leaves but not lobed, the phyllaries are dark green to blackish, the florets number 15 to 38.
Above: 1st photo - Plant blooms from late August - note the small upper leaves. 2nd photo - mature flowers turning to seed in early October. 3rd photo - A magnificent multi-stemmed specimen in the Upland Garden.
Below: 1st photo - Mature stems have a purplish tint with darker blotches. 2nd photo and photo further below - Differences in lobe pattern on the larger lower leaves.(
Below: Each flower head has 7 to 9+ ray florets with whitish corollas and rays. On the outside are a series of short bractlets (calyculi) at the base of the flower head, and a series long and pointed phyllaries, purplish to maroon in color. If this wasn't an Aster family plant, one might mistake them for elongated sepals. Each floret has a long exserted style with a bifurcated tip. There are no disc florets in the Prenanthes.
Below: 1st photo - The lower leaves can be deeply lobed and triangular at the base compared to the smaller upper stem leaves. 2nd photo - The root has short thickened taproots below the crown.
Notes: White Rattlesnake Root is indigenous to the Garden area. Eloise Butler catalogued it on May 31 1907. She also planted, in October 1911, plants she collected within Glenwood Park [which surrounded the area of the Garden and is now named Theodore Wirth Park]. Martha Crone planted it in 1946 and '47 and it was listed on her 1951 census of Garden Plants. Susan Wilkins added plants in 2011, '12 and '14. It is native to most of Minnesota except some counties in the SW quarter. In North America it is concentrated in upper eastern half of the U.S., not found in the SE Gulf states and in Canada it is reported from Manitoba eastward to Quebec.
There are four species of the genus Prenanthes that are native to Minnesota and all have quite similar common names: P. aspera Michx., known as Rough Rattlesnake-root or Hairy Rattlesnake-root; P. crepidinea Michx., known as Nodding Rattlesnake-root; P. racemosa Michx., known as Purple Rattlesnake-root or Smooth Rattlesnake-root; and our species in the Garden, P. alba L., White Rattlesnake-root.
Eloise Butler wrote in 1911 in her unpublished work The Wild Botanic Garden: "On the borders of copses, a graceful composite, Prenanthes alba, may still be seen. One notices the broad, halberd-shaped leaves long before the flowering time and wonders what sort of plant it is. And later on is sure to mark the pendant bells of the flower heads with their delicate, mauve-colored bracts enclosing whitish petals. A closely allied species has local repute in South Carolina and elsewhere as a remedy for snakebites, so the genus is known as rattlesnake root. This “gall-of-the-earth” has subterranean tubers that are bitter enough to counteract any virulence, if, as was once believed, the more ill tasting the medicine, the more potent it is to cure. The flowers go to seed like the dandelion, but the parachute of fine hairs that wafts the seed abroad is tawny brown instead of white."
Lore and Uses: It is not believed that the plant has ever been listed in the U. S. Pharmacopoeia, but in 1887 Dr. Charles Millspaugh reported that it has “Been known in domestic practice from an early date and is said to be an excellent antidote to the bite of the rattlesnake and other poisonous serpents.” In American Medicinal Plants, 1887, (Ref. #27) he goes on to explain exactly how it was used. The milky juice was recommended to be taken internally, while the leaves, steeped in water were to be frequently applied to the wound. Also, a decoction of the root could be taken.
In Indian Herbalogy of North America, (Ref #12) Alma Hutchens gives the recipe for using the juice and root for dysentery or diarrhea. The juice could be drank. With the root you would grate it into small pieces. One teaspoonful of granulated root steeped in one cup of boiling water. Drink it cold, one cup a day, a large mouthful at a time (probably because it tasted terrible). Kelly Kindscher (Ref. #14a) reports how the Choctaws made a tea of the tops for use to mitigate pain, while fellow Minnesotan Frances Densmore (Ref. #5) reported from her conversations with Minnesota White Earth Chippewa women, that the Chippewa made a broth from the root that was drunk by women after childbirth to promote the flow of milk.
Many of these uses may stem from the old “Doctrine of Signatures,” where a relationship was presumed between a human ailment or body part and the color, shape or characteristic of a plant. Nothing scientific mind you, but practical folk medicine that science usually (but not always) cannot duplicate.
But the most fascinating use of the Rattlesnake-root plant, (getting finally to its common name) can only be best described by a direct quotation and it will be up to you to believe it or not! William Byrd of Virginia wrote in 1728 that “the rattlesnake has an utter antipathy to this plant, in-so-much that if you smear your hand with the juice of it, you may handle the viper safely. Thus much can I say of my own experience, that once in July, when these snakes are in their greatest vigor, I besmear’ed a dog’s nose with the powder of this root and made him trample on a large snake several times, which however, was so far from biting him that it perfectly sicken’d at the dog’s approach and turn’d its head from him with the utmost aversion.” (History of Folklore of North American Wildflowers, 1999, Timothy Coffey. Ref. #3).
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.
Friends of the Wild Flower Garden, Inc. Text and photos are by G. D. Bebeau unless otherwise credited. "www.friendsofthewildflowergarden.org"