Tag: phytophotodermatitis

Weeds, Weed Control and Mulch

Poisonous to Touch Weed Series: Wild Parsnip (Pastinaca sativa)

Wild parsnip (Pastinaca sativa) aka poisonous parsnip is one of the phototoxic weeds we grow here in Canada. It is a non-native and as such is an aggressive and invasive species. It is the only one of the phototoxic weeds that has a yellow flower, the others bearing white umbels. It’s pinnately compound leaves are also quite different than the palmately compound leaves of cow … Continue reading Poisonous to Touch Weed Series: Wild Parsnip (Pastinaca sativa)

Kimberley PacholkoLeave a comment
Weeds, Weed Control and Mulch

Poisonous to Touch Weed Series: Cow Parsnip (Heracleum maximum)

Cow Parsnip (Heracleum maximum) aka Common Parsnip or American Parsnip, is a native plant that widely grows in north America. It is a large plant rising up to heights of 1-2.5 m (3-8 ft.) when in flower. Like giant hogweed, cow parsnip contains organic chemicals within it’s sap called furanocoumarins. This chemical is activated by ultraviolet radiation and the result is severe burning, blistering and … Continue reading Poisonous to Touch Weed Series: Cow Parsnip (Heracleum maximum)

Kimberley PacholkoLeave a comment
Weeds, Weed Control and Mulch

Poisonous to Touch Weed Series: Giant Hogweed (Heracleum mantegazzianum)

Giant hogweed (Heracleum mantegazzianum) is likely the largest and most dangerous to touch perennial weed in North America. In Ontario it commonly reaches heights of 3-4.5m but in other parts of the world it can reach heights of 5.5m (MacDonald F. and Anderson H. 2012). There are a few other Giant Hogweed species that are a bit smaller in size but Heracleum mantegazzianum is the … Continue reading Poisonous to Touch Weed Series: Giant Hogweed (Heracleum mantegazzianum)

Kimberley PacholkoLeave a comment