Heracleum sphondylium, commonly known as hogweed or common hogweed, is a herbaceous perennial plant in the carrot family Apiaceae, which includes fennel, cow parsley, ground elder and giant hogweed. It is native to most of Europe, western Asia and northern Africa, but is introduced in North America and elsewhere. Other common names include cow parsnip (not to be confused with Heracleum maximum of North America) or eltrot (which may refer to other species). The flowers provide a great deal of nectar for pollinators.
Description
Heracleum sphondylium is a herbaceous, flowering plant. It is a tall, roughly hairy plant reaching up to in height. The hollow, ridged stem with bristly hairs arises from a large tap root. The leaves can reach in length. They are once or twice pinnate, hairy and serrated, divided into 3–5 lobed segments.
Heracleum sphondylium is most commonly a polycarpic perennial plant, not a biennial as sometimes claimed. The flowers are arranged in umbels, either flat or slightly convex, 4–25 cm in diameter, usually with 10–20 hairy, somewhat unequal rays. each 2–12 cm long. Each flower has five white or rarely pinkish-white to purplish petals. The central flowers of the umbel have radial symmetry (actinomorphic), while the flowers around the perimeter of the umbel have bilateral symmetry (zygomorphic) since the outermost petals are enlarged. The winged fruits are flattened schizocarps, elliptical to rounded and glabrous, about 1 cm long.
The characteristic 'farm yardy' smell or the observation that pigs would eat the foliage and roots of hogweed is perhaps the origin of its common name.
Heracleum sphondylium is smaller than Heracleum mantegazzianum (giant hogweed) and Heracleum sosnowskyi (Sosnowsky's hogweed). It contains some of the same phytophototoxic compounds (furanocoumarins), albeit at lower concentrations, and there is evidence that the sap from common hogweed can also produce phytophotodermatitis (burns and rashes) when contaminated skin is exposed to sunlight.
Similar species
Heracleum sphondylium is often confused with Heracleum sibiricum, also known as Heracleum sphondylium subsp. sibiricum. The latter is similar to the typical subsp. sphondylium except that it has yellowish-green flowers that are actinomorphic throughout the umbel arrangement.
Taxonomy
Heracleum sphondylium is one of five species of Heracleum described by the Swedish botanist Carl Linnaeus in 1753 (the other four being H. alpinum, H. austriacum, H. panaces, and H. sibiricum).
Subspecies
Since the morphology of Heracleum sphondylium is highly variable throughout its range, many infraspecies have been described. In 1968, Flora Europaea recognized 8 subspecies (plus the typical subspecies). , World Flora Online (WFO) and Plants of the World Online (POWO) accept 18 and 14 subspecies, respectively.
Unlike WFO, POWO recognizes subsp. carpaticum, subsp. cyclocarpum, and subsp. sibiricum at species rank, with subsp. flavescens being a synonym of Heracleum sibiricum. In 1971, Brummitt lumped Heracleum lanatum of North America into subsp. montanum of Europe. , POWO recognizes these taxa as Heracleum maximum and subsp. elegans, respectively.
Other infraspecies
The marginal flowers of Heracleum sphondylium subsp. sphondylium are typically zygomorphic, that is, the outer petals of the marginal flowers of a secondary umbel are markedly larger, often two or more times as large as the inner petals. In 1846, the German botanist Wilhelm Ludwig Petermann described an infraspecies of subsp. sphondylium that lacks this characteristic. Subsequently, various authors have referred to it as f. subregulare or var. subregulare, but the correct name of the infraspecies is Heracleum sphondylium var. subregulare The epithet subregulare means "almost regular", a reference to the atypical marginal flowers of the variety.
In 1961, the Polish botanist Maria J. Gawłowska constructed the following taxonomy for Heracleum sphondylium: