'Hawkweed' refers to any species in the very large genus ''Hieracium'' and its
segregate genus ''Pilosella'', in the
sunflower family (Asteraceae).
They are common
perennials, occurring worldwide in temperate regions, except in
Australasia. They are usually small and weedy. Only a few are
ornamental plants. Most are considered to be troublesome
weeds.
They grow to 5-100 cm tall, and feature clusters of yellow, orange or red
flower heads, similar to
dandelions, atop a long, fuzzy stalk.
''Hawkweed'' is a slang name taken from
folklore which says that
hawks would chew on the plant to improve their eyesight.
Hawkweeds are used as food plants by the
larvae of some
Lepidoptera species including
Autumnal Rustic,
Broad-barred White,
Dot Moth,
Hebrew Character,
Large Yellow Underwing,
Lime-speck Pug and
The Shark and also by small beetles.
Taxonomy
Few genera are more complex and have given botanists such a headache due to the great number of
apomictic species. Through
speciation by rapid
evolution,
polyploidy, and possibly also
hybridisation, this variable genus has given rise to thousands of small variations and more than 10,000 microspecies, each with their own taxonomic name, have been described. The database
IPNI provides more than 12,000 named
taxa for this genus, including subspecies and synonyms, but it is far from complete.
Attempts have been made to break up this genus in ''Hieracium'' (sensu stricto; retaining most species) and ''Pilosella'' (about 16 species), based on
achene characters and the occurrence of
stolons.
Species
The list below is a selection of species for which common names are recorded. A more complete list is given in
List of Hieracium species.
;''Hieracium''
★ ''
Hieracium albiflorum'' -
White-flowered Hawkweed
★ ''
Hieracium alpinum'' -
Alpine Hawkweed
★ ''
Hieracium amitsokense'' - Royal Hawkweed
★ ''
Hieracium angmagssalikense'' - Blackstyle Hawkweed

''Hieracium amplexicaule''
★ ''
Hieracium argutum'' - Southern Hawkweed
★ ''
Hieracium atratum'' - Polar Hawkweed
★ ''
Hieracium aurantiacum'' - Orange Hawkweed, Devil's Paintbrush
★ ''
Hieracium bolanderi'' - Bolander's Hawkweed
★ ''
Hieracium bombycinum'' - Spanish King-devil
★ ''
Hieracium caespitosum'' - Meadow Hawkweed, Yellow Hawkweed
★ ''
Hieracium canadense'' - Canadian Hawkweed
★ ''
Hieracium carneum'' - Huachuca Hawkweed
★ ''
Hieracium cynoglossoides'' - Houndstongue Hawkweed
★ ''
Hieracium devoldii'' - Devold's Hawkweed
★ ''
Hieracium fendleri'' - Yellow Hawkweed
★ ''
Hieracium florentinum'' - Smooth Hawkweed, King Devil, Pale Hawkweed
★ ''
Hieracium floribundum'' - Yellow Devil Hawkweed
★ ''
Hieracium glomeratum'' - Queen Devil Hawkweed
★ ''
Hieracium gracile'' - Slender Hawkweed
★ ''Hieracium greenii'' - Maryland Hawkweed
★ ''Hieracium groenlandicum'' - Greenland Hawkweed

''Pilosella aurantiacum''
★ ''Hieracium gronovii'' - Queendevil Hawkweed
★ ''Hieracium horridum'' - Prickly Hawkweed
★ ''Hieracium hyparcticum'' - Arctic Hawkweed
★ ''Hieracium inuloides'' - Butterfly Hawkweed
★ ''Hieracium ivigtutense'' - Holsteinsborg Hawkweed
★ ''Hieracium kalmii'' - Kalm's Hawkweed
★ ''Hieracium lachenalii'' - Common Hawkweed
★ ''Hieracium laevigatum'' - Smooth Hawkweed
★ ''Hieracium lemmonii'' - Lemmon's Hawkweed
★ ''Hieracium lividorubens'' - Cow Hawkweed
★ ''Hieracium longiberbe'' - Longbeard Hawkweed

Common Hawkweed (''Hieracium lachenalii'') ?
★ ''Hieracium longipilum'' - Hairy Hawkweed
★ ''Hieracium maculatum'' - Spotted Devil's Paintbrush
★ ''Hieracium megacephalon'' - Coastalplain Hawkweed
★ ''Hieracium musartutense'' - Musartut Hawkweed
★ ''Hieracium nepiocratum'' - Lindenows Fjord Hawkweed
★ ''Hieracium murorum'' - Wall Hawkweed
★ ''Hieracium paniculatum'' - Allegheny Hawkweed
★ ''Hieracium pilloselloides'' - Tall Hawkweed, Glaucous King Devil
★ ''Hieracium plicatum'' - Boreal Hawkweed
★ ''Hieracium praealtum'' - Kingdevil Hawkweed
★ ''
Hieracium pratense'' - Yellow Hawkweed
★ ''Hieracium pringlei'' - Pringle's Hawkweed
★ ''Hieracium rigorosum'' - Rockyscree Hawkweed
★ ''Hieracium robinsonii'' - Robinson's Hawkweed
★ ''Hieracium rusby'' - Rusby's Hawkweed
★ ''Hieracium sabaudum'' - New England Hawkweed
★ ''Hieracium scabrum'' - Rough Hawkweed
★ ''Hieracium scholanderi'' - Kap Farvel Hawkweed
★ ''Hieracium scouleri'' - Woollyweed
★ ''
Hieracium snowdoniense'' - Snowdonia hawkweed
★ ''Hieracium stelechodes'' - Dronning Maries Dal Hawkweed
★ ''Hieracium stiptocaule'' - Igaliko Fjord Hawkweed
★ ''Hieracium sylowii'' - Brownstyle Hawkweed
★ ''Hieracium tridentatum'' - Treetooth Hawkweed
★ ''Hieracium trigonophorum'' - Singlehead Hawkweed
★ ''Hieracium triste'' - Woolly Hawkweed
★ ''Hieracium umbellatum'' - Narrowleaf Hawkweed
★ ''Hieracium venosum'' - Rattlesnake Weed
★ ''Hieracium villosum'' - Shaggy Hawkweed
★ ''Hieracium wellwitchii'' - Silver Mouse-ear
★ ''Hieracium wrightii'' -
Roughstem Hawkweed
;''Pilosella''
★ ''Pilosella aurantiaca'' (''Hieracium aurantiacum'') -
Orange Hawkweed
★ ''Pilosella officinarum'' (''Hieracium pilosella'') -
Mouse-ear Hawkweed
References
★ Stace, C. A. 1998. Sectional names in the genus Hieracium (Asteraceae) sensu stricto. ''Edinb. J. Bot''. 55: 417-444.
★ Shetler, Stanmyn; Fet, Galina & Unumb, Ellen A. eds. ''Flora of the U.S.S.R.'' Volume XXX: Compositae, Genus Hieracium (translated from Russian), 706 pp., illustr., Washington D.C., Smithsonian Institution Libraries, 2002.

Panicled Hawkweed (''Hieracium paniculatum'')

Mouse-ear hawkweed (''Pilosella officinarum'')

Mouse-ear Hawkweed (''Pilosella officinarum'')
from Thomé ''Flora von Deutschland, Österreich und der Schweiz'' 1885