Sosnowsky's hogweed, one of the most toxic plants in Poland, is particularly dangerous in hot weather as even small amounts of its juice can cause second and third-degree burns on skin exposed to sunlight.
Its oils can also cause irritation to the upper respiratory tract, nausea and vomiting, headaches and conjunctivitis.
The plant blooms from July to September and produces thousands of seeds which are easily distributed, also by humans.
A native of the Caucasus, the hogweed was first brought to Poland in the 1950s from the then Soviet Union as a silage plant, to be used as animal fodder. Probably first testing of the hogweed was done at the Medical University in Wrocław. Attempts to cultivate it on a wider scale were soon discontinued because of its toxic properties, however the hogweed had begun to spread uncontrolledly all over Poland.
Even though experts say that only 10 per cent of the plants flower and bear seeds, the ease with which the hogweed spreads means that it is difficult to eradicate and experts say that there is no one way of dealing with it.
Poland's municipal guards say that already this year they have received dozens of reports concerning the appearance of Sosnowsky's hogweed plants.