Mix some plant sap — such as giant hogweed — with sunlight and you'll find phyto plus photo equals dermatitis, an itchy skin rash.

It's the combo of plant sap and sunlight, which can produce an irritating rash.

In the early summer, froghopper nymphs cover themselves in a froth-like mass, which protects them from desiccation, then feed on the plant sap and cause wilting.

The plant sap and leaves are reputed to be toxic, and decaying leaves from the plant are toxic to other species of plant.

The media workers also gain subsistence from plant sap they ingest whilst physically cutting out sections of leaf from a variety of plants.