Hieracium , known by the common name hawkweed and classically as hierakion, 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), which are part of the tribe Cichorieae. Hawkweeds, with their 10,000+ recorded species and subspecies, do their part to make Asteraceae the second largest family of flowering plants. Some botanists group all these species or subspecies into approximately 800 accepted species, while others prefer to accept several thousand species. Since most hawkweeds reproduce exclusively asexually by means of seeds that are genetically identical to their mother plant, clones or populations that consist of genetically identical plants are formed and some botanists prefer to accept these clones as good species whereas others try to group them into a few hundred more broadly defined species. What is here treated as the single genus Hieracium is now treated by most European experts as two different genera, Hieracium and Pilosella, with species such as Hieracium pilosella, Hieracium floribundum and Hieracium aurantiacum referred to the latter genus. Many members of the genus Pilosella reproduce both by stolons and by seeds, whereas true Hieracium species reproduce only by seeds. In Pilosella, many individual plants are capable of forming both normal sexual and asexual (apomictic) seeds, whereas individual plants of Hieracium only produce one kind of seeds. Another difference is that all species of Pilosella have leaves with smooth (entire) margins whereas most species of Hieracium have distinctly dentate to deeply cut or divided leaves.
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.
Hypochaeris radicata – also known as catsear, flatweed, cat's-ear, hairy cat's ear, or false dandelion – is a perennial, low-lying edible herb often found in lawns. The plant is native to Europe, but has also been introduced to the Americas, Japan, Australia, and New Zealand, where it can be an invasive weed. It is listed as a noxious weed in the northwestern U.S. state of Washington.
Lycopodium clavatum is the most widespread species in the genus Lycopodium in the clubmoss family.
Gaillardia pulchella is a North American species of short-lived perennial or annual flowering plants in the sunflower family.
Pilosella caespitosa is like several other Pilosella species and has a similar appearance to many of the hawkweeds.
Hieracium horridum, known as the prickly hawkweed or shaggy hawkweed, is a species of plant in the family Asteraceae. It gets its name from the long, dense, shaggy white to brown hairs (trichomes) which cover all of the plant parts of this plant species. The species is native to Oregon, California, and Nevada in the western United States.
Trixis inula, the tropical threefold, is a plant species native to Texas, Mexico, Central America, northern South America, and the West Indies. It is found on open, sandy sites such as roadsides, thorn scrub, thickets, etc.
Chromolaena ivifolia called ivy-leaf false thoroughwort, or ivyleaf thoroughwort, is a species of flowering shrub in the family Asteraceae. It is native to North America and South America, from the south-eastern United States to Argentina.
Elephantopus mollis, common names tobacco weed, and soft elephantsfoot, is a tropical species of flowering plant in the family Asteraceae.
Gamochaeta simplicicaulis, the simple-stem cudweed or simple-stem everlasting, is a species of flowering plant in the sunflower family. It is native to South America and has become naturalized in Australia, New Zealand, and the southeastern United States.
Gnaphalium polycaulon, the many stem cudweed, is a plant species in the family Asteraceae. It is widespread across much of Mesoamerica, South America, and the West Indies, and naturalized in parts of Asia and Africa.
Hieracium traillii is a species of hawkweed known by the common name Maryland hawkweed.
Hieracium abscissum is a species of plant in the tribe Cichorieae within the family Asteraceae. It is considered to be native to the south-western United States, Mexico and Central America.
Hieracium longiberbe, known by the common name longbeard hawkweed, is a rare North American plant species in the tribe Cichorieae within the family Asteraceae It has been found only in the Columbia River Gorge along the border between the states of Washington and Oregon in the northwestern United States.
Hieracium longipilum, the hairy hawkweed, is a North American plant species in the tribe Cichorieae within the family Asteraceae. It is widespread across much of central Canada and the central United States from Ontario south to Texas and Louisiana. There are old reports of the species growing in Québec, but apparently does not grow there now.
Hieracium pringlei, common name Pringle's hawkweed, is a North American plant species in the tribe Cichorieae within the family Asteraceae. It is native to Mexico with additional populations in Guatemala, Arizona, and New Mexico.
Hieracium robinsonii, or Robinson's hawkweed, is a North American plant species in the tribe Cichorieae within the family Asteraceae. It is native to eastern Canada and the northeastern United States. There are reports of it formerly growing in Newfoundland, but it does not appear to grow there now.
Hieracium scabrum, the rough hawkweed, is a North American plant species in the tribe Cichorieae within the family Asteraceae. It is native to eastern and central Canada and the eastern and central United States from Nova Scotia west to Ontario, Minnesota, and Kansas south as far as Georgia and Oklahoma.
Hypochaeris microcephala, the smallhead cat's ear, is a species of plants in the tribe Cichorieae within the family Asteraceae. It is native to South America and naturalized in parts of North America.
Xyris jupicai, common name Richard's yelloweyed grass, is a New World species of flowering plants in the yellow-eyed-grass family. It is widespread in North America, South America, Mesoamerica, and the West Indies.
