Weed Technology 2007 21:279–287 Intriguing World of Weeds Wild Parsnip (Pastinaca sativa): A Troublesome Species of Increasing Concern Kristine M. Averill and Antonio DiTommaso* Although many of us fondly associate parsnips with a rustic, there are eight species (Table 1) and four subspecies (Table 2) home-cooked meal, there is also a wild variety that is in the Pastinaca genus (Menemen and Jury 2001). increasingly causing problems as a weed in North America. The four subspecies of wild parsnip are found across The cultivated variety is a subspecies of Pastinaca sativa Eurasia. P. sativa L. ssp. sativa is widely cultivated throughout (Pastinaca sativa ssp. sativa) and contains lower amounts of the Northern Hemisphere; ssp. urens [Req. ex Godron] C¸ elak. the problematic furanocoumarins than the wild version. Wild and ssp. sylvestris [Mill.] Rouy and Camus are distributed in parsnip (Pastinaca sativa L. PAVSA) is an introduced several countries including France, Georgia, Italy, Russian facultative biennial from Eurasia. It has spread throughout Federation, Switzerland, and Ukraine; and ssp. latifolia the United States and southern Canada and is now colonizing [Duby] DC., is endemic to Corsica (Menemen and Jury old fields, railroad embankments, roadsides, and waste areas. 2001; USDA ARS 2006). These latter three species are not Wild parsnip contains furanocoumarins, which deter herbi- known to be present in the United States or Canada. vores from eating its foliage. These compounds can also cause Within the Apiaceae, some of the most economically phytophotodermatitis in humans and livestock, a condition important species are vegetables including carrot (Daucus that results in patches of redness and blisters on the skin when carota L.), celery (Apium graveolens L.), celeriac (A. graveolens they come into contact with the sap or ingest parts of the plant L. var. rapaceum [Mill.] DC.), and fennel (Foeniculum vulgare in the presence of sunlight. Few people, including medical Mill. var. dulce Battandier [Trabut]). All of these crops are professionals, recognize the plant or associate it with the burns used for their swollen roots or leaf bases, which are present by it causes. Recently, wild parsnip has received increasing the end of the first growing season. There are also several attention as expanding populations have resulted in more economically important herbs in the Apiaceae including anise frequent human and livestock contact with the plant. This (Pimpinella anisum L.), caraway (Carum carvi L.), chervil article reviews important aspects of the etymology, distribu- (Anthriscus cerefolium [L.] Hoffm.), coriander (Coriandrum tion, history, biology, and management of wild parsnip. A key sativum L.), dill (Anethum graveolens L.), lovage (Levisticum objective of this review is to raise awareness of the potential officinale Koch.), and parsley (Petroselinum crispum [Mill.] health problems caused by wild parsnip and to stimulate Nym.) (Zomlefer 1994). research that will lead to effective management of this The Latin name Pastinaca is said to be derived from the increasingly problematic species. Latin word pastino, ‘‘to prepare the ground for planting of the vine’’ (Fernald 1950), but could also originate from the Latin word pastus, meaning ‘‘food,’’ referring to the edible root. The Etymology epithet sativa means ‘‘sown,’’ indicating that the plant has been cultivated (Menemen and Jury 2001). Common names Wild parsnip is an herbaceous biennial (or more correctly, of wild parsnip include: parsnip (USDA NRCS 2006), bird’s a monocarpic perennial) within the Apiaceae (Umbelliferae) nest, hart’s-eye, heeltrot, hockweed, madnip (Klaber 1942), (carrot, parsley) (Zomlefer 1994), subfamily Apioideae, tribe queen weed, and tank (Jaques 1959). Synonyms of Pastinaca Peucedaneae, and subtribe Ferulinae (Peucedaninae) based on sativa L. include Pastinaca sativa L. var. pratensis Pers., Drude’s (1897–1898) classification of the Apiaceae (Downie Peucedanum sativum S. Wats. (French 1971), Pastinaca et al. 1998). However, Theobald (1971) noted that Pastinaca sylvestris L., and Pastinaca sativum (L.) Bentham ex Hooker shares most floral and fruit anatomical characteristics with fil. There is confusion in the taxonomy of wild parsnip. Bailey members of the genus Heracleum, which are classified in the (1951) refers to the cultivated parsnip as P. sativa L. and to Tordyliinae subtribe. This taxonomic similarity suggests the wild parsnip as P. sativa L. var. sylvestris DC., whereas distinct differences within the subtribes of the Peucedaneae. Clapham et al. (1962) consider P. sativa L. to be the wild In the United States and Canada, there are 94 known genera parsnip. Somner and Jillson (1967) refer to the cultivated and 440 species of Apiaceae (Zomlefer 1994). Wild parsnip is parsnip as P. sativa L. var. hortensis and to the wild parsnip as the only known species within the Pastinaca genus in the P. sativa L. var. pratensis Pers. The differences between the United States and Canada (S. J. Darbyshire, personal cultivated and wild parsnips appear quite obscure. communication; Menemen and Jury 2001). Worldwide, DOI: 10.1614/WT-05-186.1 Description * Research Assistant and Associate Professor, Department of Crop and Soil Sciences, Cornell University, Ithaca, NY 14853. Corresponding author’s E-mail: Wild parsnip is a tall, stout, herbaceous plant with a long, [email protected]. thick, and deep taproot (Gleason and Cronquist 1991) Averill and DiTommaso: Wild parsnip N 279 Table 1. Key for type species: Pastinaca L. (adapted from Menemen and Jury and Cronquist 1991; Lorenzi and Jeffrey 1987). The fruits 2001). contain two mericarps, each with one seed (Hendrix et al. 1. Leaves simple and glabrous on both sides............P. lucida 1991) and consisting largely of tissues of an inferior ovary 1. Leaves pinnate and hairy on both sides (Jackson 1933). Fruits are considered tonic and are said to be 2. Petals pinkish.............................P. zozimoides both carminatives, which aid in digestion, and emmenago- 2. Petals yellow gues, which induce menstrual flow (French 1971). The ploidy 3. Bracts and bracteoles present 5 4. Petals glabrous or subglabrous on level of wild parsnip is 2n 22 (Gleason and Cronquist dorsal surface . ........................P. hirsuta 1991). Wild parsnip is andromonoecious, with individual 4. Petals hairy plants bearing both male and hermaphroditic flowers. The 5. Leaves elliptic to ovate-triangular, hermaphroditic flowers are protandrous, going through mericarp elliptic to ovate, rays generally a staminate, then a pistillate stage (Nitao and Zangerl more than 10 .......................P. pimpinellifolia 5. Leaves oblong to elliptic, mericarp elliptic 1987), with little or no overlap between the stages (temporal to orbicular, rays generally less than 10 . ....P. armena dioecism), either within or between umbels, thus preventing 3. Bracts and bracteoles absent cross pollinations between flowers of the same plant (Cruden 6. Leaves 2-pinnate, rays unequal, brown and Hermann-Parker 1977). veins absent . ........................P. fleischmanni 6. Leaves 1-pinnate, rays equal or subequal, Many species in the Apiaceae, including wild parsnip, can brown veins present cause phytophotodermatitis (PPD) in humans if skin is 7. Petals hairy, mericarp ovate, exposed to the light-sensitizing sap of the species and commisural surface waxy. ..............P. divaricata ultraviolet (UV-A 320–380 nm) radiation. The reaction 7. Petals glabrous or subglabrous, mericarp elliptic, commisural surface glabrous, very consists of a burning erythema beginning approximately rarely waxy . ........................P. sativa 24 h after exposure, which may later blister. The inflamma- tory reaction may be mild enough to go undetected, but can also cause severe postinflammatory hyperpigmentation lasting (Figure 1). The plant is most often a biennial, but can behave weeks to months. Furanocoumarins (furocoumarins) are the as a monocarpic perennial (Baskin and Baskin 1979; Gleason photosensitizing chemical compounds found in the sap of and Cronquist 1991), thus dying after the production of wild parsnip and cause the phototoxic reaction (Berenbaum flowers and seeds (Kline 1986). The roots can grow to a 1.5-m 1995). The sap of the plant is most irritating when the plant is depth (Gleason and Cronquist 1991), and are funnel-shaped, in flower (Kennay and Fell 1990). white, aromatic, mucilaginous, sweet, and slightly acrimonius. Many members of the Apiaceae, including other weedy The root has been a widely utilized esculent since early times species, such as wild carrot (Daucus carota L.), poison hemlock (Hedrick 1919). Wild parsnip does not reproduce vegetatively (Conium maculatum L.), spotted water hemlock (Cicuta (Hendrix and Trapp 1992). Rosettes grow near the soil maculata L.), and giant hogweed (Heracleum mantegazzianum surface and bear alternate, pinnately compound leaves, Sommier and Levier) share similar characteristics with wild approximately 15 cm in length (Lorenzi and Jeffrey 1987). parsnip. Distinguishing features of wild parsnip, however, The plant requires 2 or more years to mature, at which time include its yellow flowers, pinnately compound stem leaves plants bolt, form a grooved aerial shoot and flower (Baskin that are divided into at least five coarsely-lobed leaflets, and its and Baskin 1979). Lower leaves have longer petioles than the distinctive parsnip odor (Alex 1992; Kennay and Fell 1990) upper leaves, which are sometimes sessile. Each leaf has 5–15