Flower:

Yellow flowers in flat clusters 3 to 8 inches across at the end of branching stems. Individual flowers are tiny with 5 petals that curl under, 5 yellow stamens, and a greenish yellow center.

Leaves and stem:

Leaves are compound with 5 to 15 leaflets each, up to 18 inches long and 6 inches across, becoming smaller with fewer leaflets as they ascend the stem. Leaflets are roughly oval and coarsely toothed, hairless, often cleft or with shallow lobes. Leaves near the base of the plant are long-stalked. The main stem is hairless and grooved. First year plant is a rosette of compound leaves with flattened, grooved stalks.

Fruit:

Fruit is a flattened oval pod, slightly ribbed, about ¼ inch long that splits into 2 seeds. The ribs are slightly winged which help it float to new locations via water or wind.

Notes:

This obnoxious weed was first widely seen throughout SE Minnesota, choking roadsides, but has now spread north and west rapidly, typically following transportation corridors as many weeds do. The MN Department of Transportation tries to impliment and maintain cooperative weed managment programs but once more - so much to do, so little money. Wild Parnsip is on the top weed list for Ramsey County, but without a statewide program to eradicate it they don't stand much of a chance. A serious note on this plant: it contains furocoumarins which can make skin sensitive to light, a condition known as phytophotodermatitis, causing severe burns and blisters. A good article showing the effects is at ThePoisonGarden.co.uk. Rubber gloves, long sleeves and long pants should be worn if hand-pulling this pest plant.