The Hieracium Linnaeus genus
The words or terms in red
(actually dark orange) in the text are defined in a
The large Hieracium genus is one of
common perennials hairy herbs growing from a
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
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
There are a total of 26 species in North America, 15 of which plus one
hybrid can be found in Québec.
- Chionoracium that includes approximately 20 species
native to North America.
- Hieracium that has species native and
invasive to North America.
- Pilosella with all its species entirely European in origin; they
are invasive to North America.
The genus belong to the
Lactuceae of the
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.
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
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.
- Hieracium albiflorum
an invasive weed in southern and western Québec;
its picture is shown above.
- Hieracium caespitosum
- Hieracium flagellare
- Hieracium laevigatum
- Hieracium murorum
- Hieracium paniculatum,
a somehat rare native species.
- Hieracium pilosella
naturalized from Eurasia
in some parts of Québec.
Hieracium piloselloides naturalized from Europe,
and found nearly everywhere.
- Hieracium robinsonii
- Hieracium sabaudum
a common native species.
- Hieracium tridentatum
- Hieracium umbellatum
- Hieracium vulgatum naturalized from Eurasia,
and found in eastern Québec.