Cow-parsnip Caution

Cow-parsnip (Heracleum lanatum)
Cow-parsnip (Heracleum lanatum) is a distinctive looking plant.

Parts of the South Beach Trail in Pacific Rim National Park Reserve are lined with dense thickets of Salmonberry (Rubus spectabilis) and Thimbleberry (Rubus parviflorus). At this time of year however, they are overshadowed by the dramatic flower heads and leaves of Cow-parsnip (Heracleum lanatum). The large umbels are in various stages of flower and going to seed but there is no mistaking the look and celery smell of this distinctive plant.

Cow-parsnip is a member of Apiaceae (Carrot family), a group that includes the very similar looking (but much taller) Giant Hogweed (H. mantegazzianum). Cow-parsnip can reach heights of 3 metres while Giant Hogweed towers up to 4.5 metres tall! Seabrooke Leckie provides an excellent profile of Giant Hogweed over at the Marvelous in Nature and Hugh over at Rock-Paper-Lizard connects the plant to Peter Gabriel and Genesis’ “Return of the Giant Hogweed.” Fortunately I know that while this nasty invasive grows in many places in Vancouver Island and is on British Columbia’s Invasive Plant Watch it is not found on the South Beach Trail. However, like Giant Hogweed, Cow-parsnip sap contains furanocoumarins and is also phototoxic (although somewhat milder – I’ve handled the stems without incident and I wouldn’t think of doing that with Giant Hogweed). The chemical process that causes this phytophotodermatitis is described in fascinating detail at Watching the World Wake Up – essentially the sap causes extreme sensitivity to ultraviolet light and exposure to the sun results in a blistering rash.

Cow-parsnip (Heracleum lanatum) Leaves
Cow-parsnip (Heracleum lanatum) leaves can be very large in size.

Everything else about Cow-parsnip is also over-the-top. The leaves are divided into three segments and are the size of large dinner plates (between 10 – 40 cm across), looking something like a maple leaf on steroids. The base of the leaf stalk is sheathed and inflated. The white flowers are small but form a large umbrella-like cluster – each of these flowers produces a sunflower-like seed. It  can be found growing in profusion in wet areas like stream banks, ditches, marshes and wet meadows.

Cow-parsnip (Heracleum lanatum) Flowers
Cow-parsnip (Heracleum lanatum) forms an umbrella-like cluster of flowers.

First Nations peoples on the coast of British Columbia ate this plant as a green vegetable, peeling the young stalks and stems and eating them raw before the plant went to seed. Caution is advised as it would be unfortunate to confuse this plant with Giant Hogweed or with the deadly Poison Hemlock (Conium maculatum) or with any of the other poisonous and similar looking members of Apaiceae. Maybe it would be better to admire these beautiful native plants with an ounce or two of respect!