Hieracium (/haɪ.əˈræsiəm/),[3] known by the common name hawkweed[4] and classically as hierakion (from ancient Greek ἱέραξ, hierax 'hawk'),[5] is a genus of flowering plant in the family Asteraceae, and closely related to dandelion (Taraxacum), chicory (Cichorium), prickly lettuce (Lactuca) and sow thistle (Sonchus),[6] which are part of the tribe Cichorieae.

Hawkweeds, with their 10,000+ recorded species and subspecies,[7] do their part to make Asteraceae the second largest family of flowering plants.

Since most hawkweeds reproduce exclusively asexually by means of seeds that are genetically identical to their mother plant (apomixis or agamospermy), clones or populations that consist of genetically identical plants are formed and some botanists (especially in UK, Scandinavia and Russia) prefer to accept these clones as good species (arguing that it is impossible to know how these clones are interrelated) whereas others (mainly in Central Europe and USA) try to group them into a few hundred more broadly defined species.

A dry roadside dotted with small, ¾ inch red orange flowers, interspersed with very similar yellow ones, and often the white of daisies, is a good sign that you are in Hawkweed country.Hieracium or hawkweeds, like others in the family Asteraceae, mostly have yellow,[11] tightly packed flower-heads of numerous small flowers[8] but, unlike daisies and sunflowers in the same family, they have not two kinds of florets but only strap-shaped (spatulate) florets, each one of which is a complete flower in itself, not lacking stamens,[11] and joined to the stem by leafy bracts.

[18] In Australia, hawkweeds are invasive pests in alpine regions, all species of Hieracium are listed or declared under various State Acts.