Here is an update to the article “Hold the Parsnips” found in the Plants section of this website wherein several toxic species of the carrot family are described. According to BBC.com (June 23, 2015) a fisherman in Somerset England merely brushed against the leaves of a giant hogweed (Heracleum mantegazzianum) of the Apiaceae and regretted it. The result was a blistered and inflamed skin wound that required hospital treatment and a projected recovery period of months.
The giant hogweed was introduced to the UK in the 19th century under the assumption that it would serve as an ornamental plant! It is native to the Caucasus and southwest Asia. Worse injuries have occurred from greater contact with the plant particularly if the plant grew in bright light which stimulates increased furanocoumarin synthesis by the plant. This compound is responsible for causing phytophotodermatitis in humans. Six related furanocoumarins occur in species of the Apiaceae, all of them toxic to some degree. This class of compounds is believed to repel many insect predators but not necessarily specialist insects which have, through natural selection, gained resistance to the toxic effect of the furanocoumarins. For a photograph of giant hogweed see the original article.