Heracleum is a genus of about 60 species (depending on taxonomic interpretation) of biennial and perennial herbs in the carrot family Apiaceae. They are found throughout the temperate northern hemisphere and in high mountains as far south as Ethiopia. Common names for the genus or its species include hogweed and cow parsnip.
Heracleum sosnowskyi, Sosnowsky's hogweed, has a native range that includes the central and eastern Caucasus regions of Eurasia, extending into the southern Caucasus region called Transcaucasia. Sosnowsky's hogweed is now a common weed throughout Europe and Asia.
Heracleum persicum, Persian hogweed, is native to Iran, Iraq and Turkey. In northern Norway, the Persian hogweed is known as the Tromsø palm.
The various species of the genus Heracleum are similar in appearance with only minor differences. An outlier is H. mantegazzianum, the size of which is exceptional.
Classification and naming
Other than size, the related species H. mantegazzianum, H. sosnowskyi, and H. persicum have very similar characteristics. The common name giant hogweed usually refers to H. mantegazzianum alone but in some locales that common name refers to all three species as a group.
The morphological similarity of species within the genus Heracleum and the difficulty of botanical identification has led to numerous synonyms and naming issues. For example, the classification of the species now widely known as H. maximum has been inconsistent. In the literature, the scientific names H. lanatum, H. maximum, and others are used interchangeably. Prior to 2000, the former name was most popular, but today the latter name is in vogue.
To make matters worse, the common names "hogweed" and "cow parsnip" are overused. In particular, both H. maximum and H. sphondylium are often referred to as cow parsnip. To avoid confusion, these species are sometimes referred to as American cow parsnip and European cow parsnip, respectively.
Most species of the genus Heracleum are known to cause phytophotodermatitis. In particular, the public health risks of giant hogweed (H. mantegazzianum) are well known.
At least 36 species of the genus Heracleum have been reported to contain furanocoumarin, a chemical compound that sensitizes human skin to sunlight. Of those, at least 25 species contained a psoralen derivative, either bergapten (5-methoxypsoralen) or methoxsalen (8-methoxypsoralen). Three of those species (H. mantegazzianum, H. sosnowskyi, and H. sphondylium) were found to contain both psoralen derivatives.
^Bailey, L.H.; Bailey, E.Z.; the staff of the Liberty Hyde Bailey Hortorium (1976). Hortus third: A concise dictionary of plants cultivated in the United States and Canada. New York: Macmillan. ISBN978-0-02-505470-7.CS1 maint: Multiple names: authors list (link)
^ ab"Heracleum L."Tropicos.org. Missouri Botanical Garden. Retrieved 11 Oct 2011.