Pastinaca sativa is a biennial herb, to 1.5 m tall from a fleshy taproot.
Leaves alternate, base of stalk sheathing stem; irregularly pinnate, large, leaflets 5-15, opposite, 5-10 cm long, stalkless, margins toothed, lobed and /or divided; winter rosette attractive, dark green, often somewhat variegated.
Flowers yellow, small, 5-parted, radially symmetrical, petals free, stamens alternating with petals, ovary inferior, 2-parted, inflorescence of compound umbels: a large (primary) umbrella-shaped cluster 10-20 cm wide with 15-25 rays with flowers in smaller umbrella-shaped clusters at the ends of secondary rays (individual stalks); flowering stalk produced after one or more years; blooms May-June; An obligate outcrosser, pollinated by bees and other insects (Lovell 1918; Lohman et al. 1996) .
Fruit dry, 0.5-0.7 cm long, 2-parted (a schizocarp), flattened, ribbed, lateral ribs narrowly winged; parts held together by hair-thin stalks, each 1-seeded, (much like caraway seed, Carum carvi, and typical of Apiaceae fruit); seeds ripe in July, plant dies as seeds mature, seeds dispersed through Nov.
Wetland status: UPL.
Frequency in NYC: Occasional.
Habitat: Weed of disturbed soil, along open roadsides, successional growth, part shade, in dry to moist, alkaline soil.
Notes: The root is the cultivated parsnip. Wild parsnip sap contains furanocoumarins, a group of toxins typically found in Apiaceae. Contact with plant sap can cause rash or blistering on exposure to sunlight (photodermititis) because furanocoumarins can bind with DNA in the presence of UV light (Berenbaum 1981). Flowers and developing fruit eaten by Depressaria pastinacella (parsnip webworm) (Eckardt 1995b). Apiaceae of open sites are eaten by larvae of the black swallowtail butterfly, Papilio polyxenes (Papilionidae); (Tallamy 2003; Pyle 1981). Listed as a noxious weed in some states (USDA, NRCS 2006; Douce et al. 2007).