If you have a rash or other skin problem that you think might be plant related, trying using the search engine at the Botanical Dermatology Database. I checked out my family’s old enemy Pastinaca sativa (aka wild parsnip), and learned a few things. First of all, wild parsnip and cultivated parsnip are the same thing, and you can get the blisters and subsequent skin pigmentation from either. Secondly, if your skin is wet (and whose isn’t on a hot summer day?) the reaction is more likely. Third, “the active spectral band for evoking phytophotodermatitis from the plant was found to be 320-360nm.” Okay, so that last part isn’t too helpful, but the other two things were good to know. Eating parsnips poses no problem, but if you like them enough to grow them, wear long sleeves and gloves when you harvest them.
I am very fond of the Spring-flowering colchicums, but unfortunately slugs are also, and those greedy gastropods and I have a race for who can see the flower-buds first. If I win I go out after dark with an acetylene lamp and a hatpin and spear the little army of slugs making for a tea party at the sign of the Colchicum.