Because of our experience with crops and weeds, it’s no surprise that the general public often turns to agronomists for plant identification and management advice. And it’s usually about this time of year – when Ontario puts out giant hogweed advisories and big white umbels are in bloom across Manitoba – that these calls start to pour in.
Fortunately, it’s probably not giant hogweed (Heracleum mantegazzianum) since that invasive species has yet to be found in our province. It’s more likely another member of the carrot family – cow parsnip (Heracleum maximum). Unlike its giant cousin, cow parsnip is native to Manitoba and non-invasive. It’s also very attractive to pollinators.
But even though it’s probably not giant hogweed, it’s still best not to touch it. Because, much like its giant cousin, the sap of cow parsnip may cause dermatitis when in contact with exposed skin. Symptoms include photosensitivity, a rash and/or blisters. Reactions to cow parsnip sap are generally much less severe than those to giant hogweed sap.
Information on identification of cow parsnip and giant hogweed is available from Manitoba Agriculture.