The Hieracium Linnaeus genus

Remark The words or terms in red (actually dark orange) in the text are defined in a glossary.


jun_23_12.gthmb can't be loaded. The large Hieracium genus is one of common perennials hairy herbs growing from a taproot. They grow from 5 to 100 cm tall. Their stems are usually branched and fuzzy. They have clusters of yellow, orange or red capitula, similar to the dandelions. Their seeds have a persistent and fragile pappus. There are between 250 and 1000 species in the genus, some of then used as ornamental. The genus is holarctic, its species are found in North America, Mexico, Central America, South America, Europe, Asia, Africa. The Hieracium genus is at times split in the three subgenera: There are a total of 26 species in North America, 15 of which plus one hybrid can be found in Québec.

The genus belong to the tribe Lactuceae of the Asteraceae family.

Name

The genus name is said to come form the Greek ιεραξ, the falcon, since the Roman naturalist Gaius Plinius Secundas (Pliny the Elder, AD 23 - August 24, AD 79) believed that the feathery Accipiters (a group of birds of prey in the family Accipitridae, the hawks family notably) fed on plants of this genus to strengthen their eyesight and thus, Hieracium, as named by Pliny the Elder in his Naturalis Historia (34, 114) became the genus name, and by extension the Latin name of many species of the Hieracium genus, many of these species with the Hawkweed vernacular name.

Notes

Most plants of the Hieracium genus are apomictic, forming predominantly asexual seeds, (some purely sexual forms, however, also exist) and this results in the perpetuation of morphologic variants at populational and regional levels. Through speciation by rapid evolution, polyploidy, and possibly also hybridisation, this variable genus has given rise to thousands of small variations. This a lead some botanists to name such variants as species so that up to 12 000 species names have been published, but circumscriptions of many of these 'species' seem to be more artificial than in most genera of the Asteraceae family, to which the genus belongs. Sexual species are usually diploids (2n = 18), apomictic ones are usually triploids (2n = 27).

Plants in this genus, especially Hieracium venosum (Rattlesnake Hawkweed) have been used extensively for medicinal purposes. Some species are troublesome invasive and widely distributed weeds.

(Hieracium spp. are listed as prohibited plants by AQIS to prevent their entry to Australia. They are listed as noxious weeds in New South Wales, Victoria and Tasmania, where landholders may be required to control them, and are on the list of plants prohibited entry into Western Australia.

The Hieracium of Québec

The following species if the Hieracium genus can be found in Québec: plus the hybrid Hieracium x floribundum.

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