Many of us may not realize that summer walks in Polish meadows and forests can unexpectedly involve discomfort. One of its potential sources is Sosnowski’s hogweed, an invasive plant that was brought to Poland in the 1950s. It quickly spread throughout the country, becoming a problem for nature lovers and rural residents alike. Contact with the sap of this plant can cause painful burns, and even just being near it during sunny days can lead to serious skin irritation. Sosnowski hogweed (Heracleum sosnowskyi) is a large, invasive plant native to the Caucasus. It belongs to the celery family (Apiaceae) and is characterized by a height of 1 to as much as 4 meters, large, umbrella-shaped inflorescences with white flowers, and hollow green stems with purple spots. Pine hogweed was introduced to Eastern Europe in the 1950s as a forage plant. However, it was quickly found that its toxicity and ability to spread rapidly outweighed its benefits. Today, it can be found in many European countries, including Poland (particularly abundant in Podhale, river valleys), Germany, Lithuania, Latvia and Estonia. The plant prefers moist, fertile soils and often grows along rivers, roads and in meadows and forests. The harmfulness of Sosnovsky hogweed is due to the furanocoumarins in its sap. These substances, when in contact with the skin and under the influence of light, especially ultraviolet (UV) light, cause severe burns – photodermatosis of the second and third degree. Symptoms can appear as early as several minutes after contact with the plant, reaching peak severity between 30 minutes and 2 hours. The reaction leads to severe dermatitis, manifesting as painful blisters, burns and long-lasting scarring. The intensity of the reaction depends on individual sensitivity, which increases in high temperatures, high humidity and intense sweating. The inflammation usually lasts about three days, and after a week the irritated areas darken, leaving discoloration (hyperpigmentation) for several months. Irritated skin can remain sensitive to UV light for up to several years. In addition, contact with the sap of the plant can even cause temporary or permanent blindness if the substance gets into the eyes.