Heracleum sibiricum

Heracleum sibiricum is a herbaceous, perennial, flowering plant with flowers arranged in an umbel. Each flower has five yellowish-green petals. Individual flowers may be bisexual (with a pistil and five stamens), pistillate (with no functional stamens), or staminate (with no functioning pistil).[3] The pistil is bicarpellate and syncarpous, that is, it has two carpels fused together. The ovary is glabrous (hairless) and the stylopodium (at the base of the styles) is almost always green. The fruit is composed of two mericarps, each with a single seed.

Heracleum sibiricum 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. sphondylium).[6] The specific name sibiricum suggests the taxon occurs in Siberia, a fact mentioned by Linnaeus in his description. In 1887, the Hungarian botanist Lajos Simonkai reduced its taxonomic rank to a subspecies of Heracleum sphondylium.[7] As of August 2023, Plants of the World Online (and a few other authorities) accept Heracleum sibiricum L.,[2][8] but most authorities still recognize Heracleum sphondylium subsp. sibiricum (L.) Simonk.[9][10][11][12][13]

In 1926, the Swiss botanist Albert Thellung described Heracleum sphondylium var. chaetocarpum,[14] a variety of Heracleum sibiricum. Thellung described the taxon as a variety of Heracleum sphondylium (not Heracleum sibiricum) since he recognized Heracleum sphondylium subsp. sibiricum (L.) Simonk. (not Heracleum sibiricum L.).[15] The typical form of Heracleum sibiricum has a glabrous ovary, whereas that of var. chaetocarpum has short, stiff, ascending hairs with pointy tips. The hairs are so short and sparse, they may not be visible to the naked eye. In 1961, the Polish botanist Maria Gawłowska described Heracleum sibiricum f. rarum,[16] a form of var. chaetocarpum with elongated leaf lobes.[17]

Heracleum sibiricum is native to Europe and western Asia, ranging from France and Italy to western Siberia and Mongolia.[2] For example, it occurs in northern and northeastern Poland but much less so in other parts of the country.[18] Some authors claim its native range extends into Great Britain,[19] while other sources suggest the taxon has been introduced in Britain.[10] Authorities claim the taxon is widely introduced throughout North America,[2][12] but as of August 2023, the presence of Heracleum sibiricum in eastern Canada and New England has not been confirmed.[20][21][22][23]

Heracleum sibiricum is most commonly a polycarpic perennial (not a biennial as often claimed), but approximately one-fourth of individuals are monocarpic. On average, first flowering requires 6–7 years of vegetative growth and may be delayed for up to 10 years. Although two or three (up to eight) subsequent flowerings are expected, most individuals do not flower in successive seasons. Estimates of average life span range from 12 to 16 years with a maximum age of 25 years.[24]

As of August 2023, the global conservation status of Heracleum sphondylium subsp. sibiricum (a synonym for Heracleum sibiricum) is unranked.[13]

• Gawłowska, Maria J. (1957). "Research on the distribution of Heracleum sphondylium L. and Heracleum sibiricum L. in Poland". Fragmenta Floristica et Geobotanica. 3 (1): 61–68. Retrieved 8 October 2023.
• Gawłowska, Maria J. (1961). "Taxonomy of the species Heracleum sphondylium L. and Heracleum sibiricum L. occurring in Poland and neighbouring countries". Fragmenta Floristica et Geobotanica. 7 (1): 3–39. Retrieved 8 October 2023.
• Gilman, Arthur V. (2015). New Flora of Vermont. Memoirs of The New York Botanical Garden, Volume 110. Bronx, New York, USA: The New York Botanical Garden Press. ISBN 978-0-89327-516-7.
• Haines, Arthur (2011). New England Wild Flower Society's Flora Novae Angliae: A Manual for the Identification of Native and Naturalized Higher Vascular Plants of New England. Illustrated by Elizabeth Farnsworth and Gordon Morrison. Yale University Press. ISBN 978-0-300-17154-9.
• Linnaeus, Carl (1753). Species Plantarum: exhibentes plantas rite cognitas, ad genera relatas, cum differentiis specificis, nominibus trivialibus, synonymis selectis, locis natalibus, secundum systema sexuale digestas (1st ed.). Stockholm: Impensis Laurentii Salvii. Retrieved 3 August 2023.
• Sheppard, A. W. (March 1991). "Heracleum sphondylium L.". Journal of Ecology. 79 (1): 235–258. doi:10.2307/2260795. JSTOR 2260795.
• Simonkai, Lajos (1887). Enumeratio Florae Transsilvanicae. Budapest: Kir. Magyar Természettudományi Társulat. p. 266. Retrieved 4 August 2023.
• Zych, Marcin (2006). "On flower visitors and true pollinators: The case of protandrous Heracleum sphondylium L. (Apiaceae)" (PDF). Plant Systematics and Evolution. 263 (3–4): 159–179. doi:10.1007/s00606-006-0493-y. S2CID 40995627. Retrieved 8 August 2023.