Poisonous Plants are showing up in landscapes! Over the past few years, a couple of poisonous weeds have invaded our natural areas as well as the landscapes. They’re wild parsnip and poison hemlock, and could be confused for each other, as they show up along roadsides, streams, pastures, edge of fields and woods, and even in our landscapes.

Wild parsnip – It’s a biennial, meaning foliage the first year, foliage, flowers and seeds the second. Wild parsnip has leaves that alternate, pinnately compound, with sawtooth edges. They grow 2-6 feet high, and support small, five petaled yellow flowers arranged in an umbel spanning 2-6 inches across. Now although wild parsnip roots are edible (but do not eat them), it’s the plant juice that can cause “phyto-photo-dermatitis” when it gets on your skin and is exposed to the sunlight. Your skin gets red with a rash that’s 20 times worse than poison ivy, and eventually turns brown in color which can last for several months.

Poison hemlock – Yes, the same poison used on Socrates! Again, a biennial like parsnip, poison hemlock grows 4-10 feet tall, leaves are pinnately compound and fernlike, with white flowers that have five notched petals arranged in an umbel 2-3 inches across. Very similar to Queen Anne’s lace, poison hemlock is distinguished by the purple spots and blotches along the stems. All parts of the poison hemlock are toxic to humans and animals.


Controls for these toxic weeds include hand pulling before they go to seed (protect your skin), repeated mowing, or spraying with weed killers in the lawn or Roundup in open areas – and spray when they are smaller in size. Remember, the goal in stopping them is to get rid of them before they go to seed.