Wild Parsnip (Pastinaca sativa): A Troublesome Species of Increasing Concern

Although many of us fondly associate parsnips with a rustic, home-cooked meal, there is also a wild variety that is increasingly causing problems as a weed in North America. The cultivated variety is a subspecies of Pastinaca sativa (Pastinaca sativa ssp. sativa) and contains lower amounts of the problematic furanocoumarins than the wild version. Wild parsnip (Pastinaca sativa L. PAVSA) is an introduced facultative biennial from Eurasia. It has spread throughout the United States and southern Canada and is now colonizing old fields, railroad embankments, roadsides, and waste areas. Wild parsnip contains furanocoumarins, which deter herbivores from eating its foliage. These compounds can also cause phytophotodermatitis in humans and livestock, a condition that results in patches of redness and blisters on the skin when they come into contact with the sap or ingest parts of the plant in the presence of sunlight. Few people, including medical professionals, recognize the plant or associate it with the burns it causes. Recently, wild parsnip has received increasing attention as expanding populations have resulted in more frequent human and livestock contact with the plant. This article reviews important aspects of the etymology, distribution, history, biology, and management of wild parsnip. A key objective of this review is to raise awareness of the potential health problems caused by wild parsnip and to stimulate research that will lead to effective management of this increasingly problematic species.

THE BIOLOGY OF CANADIAN WEEDS.: 84. Oenothera biennis L.

Oenothera biennis L., the common evening-primrose, is a widespread weed of roadside and waste places commonly occuring on light sandy or gravelly soils where competition is limited. The species is native to North America and, although occurring in all 10 Canadian provinces, is more common in the east than in the west. The chief factor contributing to its success as a weed is the ability to tolerate drought. A winter annual or facultative biennial, it flowers and bears seed only once in a lifetime. The small, irregularly shaped seeds have a high oil content, and contain γ linolenic acid, an uncommon fatty acid of pharmaceutical value. Oenothera biennis is a true-breeding translocation heterozygote composed of two genomes (complexes) differing genetically as well as in chromosomal end arrangement. Populations of O. biennis consist of numerous inbreeding lines, between which limited hybridization may occur.Key words: Common evening-primrose, Oenothera biennis, weed biology, population structure