Wild Parsnip (Pastinaca sativa)

 
Wild parsnip is a member of the Umbelliferae (parsnip) family. Rosettes grow close to the ground and bear leaves averaging six inches in height. The plant has a long, thick taproot, which is edible. Flowering plants produce a single, thick stem that contains hundreds of yellow umbellate flowers. The lateral flowers often overtop the terminal flowers. Depending on the habitat and growing conditions, individual flowering plants range to over four feet in height. Leaves are alternate, pinnately compound, branched, and have saw-toothed edges. Each leaf has 5-15 ovate to oblong leaflets with variable toothed edges and deep lobes.

Wild parsnip can be confused with prairie parsley (Polytaenia nuttallii), a native prairie species. Its flowers and leaves resemble those of wild parsnip. Comparatively, flowers of the prairie parsley plant are light-yellow, sparse, and typically found at the end of the stem. The leaves are pinnately compound like those of the wild parsnip, but are oblong with few teeth.

DISTRIBUTION AND HABITAT: Wild parsnip is tolerant of a wide range of conditions, including dry, mesic, and wet-mesic prairies; oak openings; and calcareous fens. It is shade-intolerant and prefers sunny conditions.

LIFE HISTORY AND EFFECTS OF INVASION: Wild parsnip can cause phytophotodermatitis to the skin. If the plant juices come in contact with skin in the presence of sunlight, a rash and/or blistering can occur, as well as skin discoloration that may last several months.

This species reproduces readily from seed. Seeds are fairly large and many are produced on one plant. As a monocarpic perennial, wild parsnip spends one or more years as a basal rosette. When conditions are favorable, it flowers, produces seed, and dies. Look for the large, coarse, flower spikes and yellow flowers from the first of June to the middle of July (although some plants may continue flowering through late summer). Optimal growing conditions apparently stimulate an increase in flowering. Apparently seeds take at least three weeks from flowering to become viable.

Wild parsnip slowly invades an area in waves following initial infestation. Once the population builds, it spreads rapidly. This species is an aggressive, Eurasian weed that frequently invades and modifies a variety of open habitats.