Wild Parsnip is a short lived biennial herbaceous plant growing on stout erect deeply ridged stems from 3 to 5 feet high. Some plants are known to be triennial. Stems are hollow except at the nodes.
Leaves: The larger basal leaves are compound, on long stalks, pinnately divided into 5 to 15 lobed or toothed leaflets, overall up to 18 inches long, each leaflet a rough diamond shape. Stem leaves attach with a sheath and become progressively smaller with fewer leaflets with those near the inflorescence becoming a simple lobed leaf arranged opposite. The first year or two the plant forms a basal rosette. Crushed leaves give a pungent odor.
The inflorescence is a compound umbel, from 4 to 8 inches wide, fairly flat with up to 25 umbellets. Smaller umbels can rise from the stem below the main umbel. Flowers open first on the inner umbellets and then the outside ones, which can then elongate their stalks to rise about the older parts of the umbel. Each umbellet will have up to 25 flowers. Unlike many other species of this family, there are no bracts on the umbel or on the umbellets.
Flowers are very small, 5-parted with yellow petals and inconspicuous sepals, with each flower on a long stalk of variable length so as to create the flat-topped umbellet. The yellow petals are initially curled inward before spreading. In the center is a green nectar receptacle around which rise the 5 stamens with yellow anthers, and the style.
Seed: Flowers mature to a flattened brown ovoid smooth seed with ribs on the side with conspicuous oil tubes. At full maturity it splits into two seeds, much like Cow Parsnip.
Toxicity: See notes below the photos. This plant causes skin burns.
Habitat: Wild Parsnip is an invasive plant taking advantage of disturbed areas, especially old fields and roadsides, in full sun in mesic to dry soil. It grows from a deep, stocky tap root. The plant requires two or more years of growth before flowering, at which point it dies after flowering (known as monocarpic). It is allowing the plant to grow into its second year and form seeds, that results in its extreme invasiveness. Once escaped from cultivation as a first year root plant, it has become unstoppable.
Names: The genus Pastinaca means "parsnip" and is thought to be from the Latin pastus, meaning 'food'. The species sativa means "cultivated" as this plant is the base species for the edible cultivated parsnips. 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.
Comparison: Wild Parsnip with its wide umbel of yellow flowers may be confused with a number of other plants with wide umbels of small flowers, but the others ae all white: Poison Hemlock, Conium maculatum, Water Hemlock, Cicuta maculata; Queen Ann's Lace, Daucus carota; Cow Parsnip, Heracleum maximum; Only Queen Ann's Lace prefers dry upland soils.
Above: Wild Parsnip can have branching in the upper stem and reach a height of 5 or more feet. The basal leaves are long stalked with 5 to 15 leaflets.
Below: The flattened umbel is up to 8" wide and composed of up to 25 umbellets.
Below: 1st photo - each umbellet has up to 25 stalked flowers. The tiny petals are first curled inward, then spreading. 2nd photo - 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 - individual leaflets are lobed and with coarse teeth. 2nd photo - the stem is deeply ridged. Leaves have a large sheath at the attachment point.
Notes: Wild Parsnip was introduced to the Wildflower Garden by Eloise Butler in 1913 with plants obtained from Glenwood Springs - nearby the Garden. It was still in the Garden at the time of Martha Crone's 1951 census but but she wrote in The Fringed Gentian™, in 1955 (Vol.3 #3) that it was not permitted in the Garden, which means she must have eliminated it. The plant is widespread in Minnesota, being known in 46 counties on the most recent (2019) DNR Census. These counties spread from the Iowa border to the arrowhead which illustrates how humans can move seeds around.
Wild Parsnip is an introduction from Eurasia and has heavily infested the states of the NE quadrant of the U.S. It is found in all the entire western half of the U.S. but somehow, the states of the SE have mostly escaped its blessings.
Toxicity: Handling the leaves and stem can cause severe skin burns and blisters, which may at first be confused with Poison Ivy, even by medical people. The chemicals in the plant cause phyto-photo-dermatitis. The constituent in the sap is furanocoumarin and once the juice is on skin it requires exposure to ultraviolet light to activate. Then 24 to 48 hours later the burns and blisters will develop. People handling the plant material need skin protection as contact is usually made outside where exposure to sun and ultraviolet are almost guaranteed. No one has been found to be immune to it; it's only a question of how long it takes for the sensitivity to kick in. Cow Parsnip can produce similar effects but to a lesser degree.
Edible: Wild Parsnip root is edible from first year plants. They can be cooked like carrots and have a sweeter taste. They were used as a sweetener in Europe before the arrival of cane sugar. Roots from the second year plant are inedible.
In his Herbal of 1597, John Gerard (Ref. #6a) has this to say about parsnips: The Parsneps nourish more then do the Turneps or the Carrots, and the nourishment is somewhat thicker, but not faultie nor bad; notwithstanding they be somewhat windie; they passe thouourh the body neither slowly nor speedily; they neither binde nor loose the bellie; they provoke urine and lust of the body; they be good for the stomacke, kidneies, bladder and lungs.
It is reported, saith Dioscorides, the Deere are preserved from bitings of Serpents, by eating of the wild Parsnep, wheupon the seed is given with wine, against the bitings and stingings of serpents.
Control Measures: Plants can be pulled fairly easily after a rain or a shovel will remove most of the root. The plant spreads by reseeding not by root offsets, so if some root is left in the ground, no matter, but remove before seed sets. Large areas of infestation can be treated with spot herbicide or my mowing. If mowing, watch from resprouts of the flower stem as invasive species tend to do so. Once the plant tries to flower and is prevented from forming seed, it dies. Wear protective clothing when working with this plant!
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"