''Crepis'', commonly known in some parts of the world as hawksbeard or hawk's-beard (but not to be confused with the related genus ''

Hieracium ''Hieracium'' (), known by the common name hawkweed and classically as (from ancient Greek ἱέραξ, 'hawk'), is a genus of flowering plant in the family Asteraceae, and closely related to dandelion (''Taraxacum''), chicory (''Cichorium''), ...

'' with a similar common name), is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of annual and

perennial In horticulture, the term perennial ('' per-'' + '' -ennial'', "through the year") is used to differentiate a plant from shorter-lived annuals and biennials. It has thus been defined as a plant that lives more than 2 years. The term is also ...

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (). The term angiosperm is derived from the Ancient Greek, Greek words (; 'container, vessel') and (; 'seed'), meaning that the seeds are enclosed with ...

s of the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Asteraceae Asteraceae () is a large family (biology), family of flowering plants that consists of over 32,000 known species in over 1,900 genera within the Order (biology), order Asterales. The number of species in Asteraceae is rivaled only by the Orchi ...

superficially resembling the

dandelion ''Taraxacum'' () is a genus of flowering plants in the family Asteraceae, which consists of species commonly known as dandelions. The scientific and hobby study of the genus is known as taraxacology. The genus has a near-cosmopolitan distribu ...

, the most conspicuous difference being that ''Crepis'' usually has branching scapes with multiple heads (though solitary heads can occur). The genus name ''Crepis'' derives from the

Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...

''krepis'', meaning "

slipper Slippers are a type of shoes falling under the broader category of light footwear, that are easy to put on and off and are intended to be worn indoors, particularly at home. They provide comfort and protection for the feet when walking indoors. ...

" or "

sandal Sandals are an open type of shoe, consisting of a sole held to the wearer's foot by straps going over the instep and around the ankle. Sandals can also have a heel. While the distinction between sandals and other types of footwear can sometim ...

", possibly in reference to the shape of the fruit.''Crepis''.
Flora of North America. The genus is distributed throughout the

Northern Hemisphere The Northern Hemisphere is the half of Earth that is north of the equator. For other planets in the Solar System, north is defined by humans as being in the same celestial sphere, celestial hemisphere relative to the invariable plane of the Solar ...

and

Africa Africa is the world's second-largest and second-most populous continent after Asia. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 20% of Earth's land area and 6% of its total surfac ...

, and several plants are known as

introduced species An introduced species, alien species, exotic species, adventive species, immigrant species, foreign species, non-indigenous species, or non-native species is a species living outside its native distributional range, but which has arrived ther ...

practically worldwide. The center of diversity is in the

Mediterranean The Mediterranean Sea ( ) is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean basin and almost completely enclosed by land: on the east by the Levant in West Asia, on the north by Anatolia in West Asia and Southern ...

Ecology

''Crepis'' species are used as food plants by the

larva A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...

e of some

Lepidoptera Lepidoptera ( ) or lepidopterans is an order (biology), order of winged insects which includes butterflies and moths. About 180,000 species of the Lepidoptera have been described, representing 10% of the total described species of living organ ...

species including the broad-barred white moth. The fly '' Tephritis formosa'' is known to attack the capitula of this plant. Seeds of ''Crepis'' species are an important food source for some bird species.

Reproduction

''Crepis'' can reproduce sexually or asexually. ''Crepis'' is insect-pollinated, typically by bees and other generalist pollinators. Species in this genus are able to produce viable seeds through hybridization. Some of these hybrids (depending on their parent species) can reproduce themselves. As an aster, flowers of ''Crepis'' are closely clustered on a

capitulum capitulum (plural capitula) may refer to: *the Latin word for chapter ** an index or list of chapters at the head of a gospel manuscript ** a short reading in the Liturgy of the Hours *** derived from which, it is the Latin for the assembly known ...

, which is surrounded by petal-like rays. Asexual reproduction (or

autogamy Autogamy or self-fertilization refers to the Cell fusion, fusion of two gametes that come from one individual. Autogamy is predominantly observed in the form of self-pollination, a Reproduction, reproductive mechanism employed by many flowering pl ...

) between flowers on the same capitulum has been observed in the genus.

Apomixis in ''Crepis''

As with several other genera in

, multiple ''Crepis'' species exhibit

apomixis In botany, apomixis is asexual development of seed or embryo without fertilization. However, other definitions include replacement of the seed by a plantlet or replacement of the flower by bulbils. Apomictically produced offspring are geneti ...

, a form of asexual reproduction where flowers produce clonal seeds without need of fertilization. Unlike sexually-reproducing individuals, which are

diploid Ploidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Here ''sets of chromosomes'' refers to the number of maternal and paternal chromosome copies, ...

, apomicts are typically

polyploid Polyploidy is a condition in which the biological cell, cells of an organism have more than two paired sets of (Homologous chromosome, homologous) chromosomes. Most species whose cells have Cell nucleus, nuclei (eukaryotes) are diploid, meaning ...

, with three or more sets of chromosomes. The mechanism of apomixis in ''Crepis'' is apospory, wherein diploid tissue arises during

meiosis Meiosis () is a special type of cell division of germ cells in sexually-reproducing organisms that produces the gametes, the sperm or egg cells. It involves two rounds of division that ultimately result in four cells, each with only one c ...

in the

ovule In seed plants, the ovule is the structure that gives rise to and contains the female reproductive cells. It consists of three parts: the ''integument'', forming its outer layer, the ''nucellus'' (or remnant of the sporangium, megasporangium), ...

. Through apospory, asexual seeds can develop spontaneously in the flowers of a non-apomictic ''Crepis''. ''Crepis'' is part of the

Cichorieae The Cichorieae (also called Lactuceae) are a tribe in the plant family Asteraceae that includes 93 genera, more than 1,600 sexually reproductive species and more than 7,000 apomictic species. They are found primarily in temperate regions of the E ...

tribe in Asteraceae, and is one of several genera of that tribe that exhibits apomixis. The largest group of asexual species is found in

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

, and is referred to as the "North American ''Crepis'' agamic complex" The agamic complex may have first arisen in the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58 Another agamic complex is thought to exist in Asia. Species known to produce apomicts in''clude C.'' ''acuminata, C.'' ''barbigera, C. intermedia,'' and ''C. occidentalis.'' Polyploid individuals may still be able to carry out sexual reproduction and therefore produce sexual offspring, allowing for the formation of new polyploid hybrids.

Reproductive interference

Apomictic individuals can prevent reproduction in sexual individuals in multiple ways. Like other apomictic species in Cichorieae, polyploid apomicts may still produce viable pollen that can be transferred to sexual diploids through the normal process of pollination. The mixed apomict-sexual parantage may produce a polyploid hybrid (as has been observed when the apomictic ''C. barbigera'' breeds with diploid species ''C. atribarba''). Seed set in the diploid may be reduced, or the pollen may produce hybrid seeds that are unable to reproduce or survive to a normal lifespan. The pollen from the apomict may also prevent germination of pollen from a diploid flower. When pollen from a polyploid individual fertilizes diploid flowers, the resultant seeds are typically polyploid, which lowers the diploid population over generations. As a result of this reproductive interference, sexual reproduction between diploid plants is reduced when apomicts enter a population. Because diploid species require pollen exchange to reproduce and apomicts can produce seeds by

parthenogenesis Parthenogenesis (; from the Greek + ) is a natural form of asexual reproduction in which the embryo develops directly from an egg without need for fertilization. In animals, parthenogenesis means the development of an embryo from an unfertiliz ...

, apomicts do not suffer any reproductive consequences in a mixed diploid-polyploid population. Meanwhile, the reproductive success of sexually-reproducing diploids falls, resulting in diploids being found more often in populations isolated from apomicts.

Evolutionary implications

Although apomixis has been considered a "blind alley of evolution", research into apomictic species and species complexes has cast doubt on this. Apomictic clades elsewhere in Cichorieae have demonstrated an ability to "revert" to a sexual mode of reproduction, reducing the risk of extinction through lack of

introgression Introgression, also known as introgressive hybridization, in genetics is the transfer of genetic material from one species into the gene pool of another by the repeated backcrossing of an interspecific hybrid with one of its parent species. Introg ...

. Speciation in ''Crepis'' has occurred through its ability to self-fertilize, hybridize, and form polyploid apomicts. Apomixis can facilitate range expansion in ways that sexual reproduction does not. Apomicts do not require input of genetic material for another individual, and can therefore produce seeds on maturity without the aid of pollinators. This allows apomictic populations to expand into new geographic areas more rapidly than sexual ones. Because apomixis in ''Crepis'' involves multiple ploidy levels, there is sufficient genetic variation for adaptation to novel ecosystems. Additionally, some ''Crepis'' apomict species have the ability to hybridize with other apomicts, resulting in genetic recombination alongside

Uses

Crete Crete ( ; , Modern Greek, Modern: , Ancient Greek, Ancient: ) is the largest and most populous of the Greek islands, the List of islands by area, 88th largest island in the world and the List of islands in the Mediterranean#By area, fifth la ...

Greece Greece, officially the Hellenic Republic, is a country in Southeast Europe. Located on the southern tip of the Balkan peninsula, it shares land borders with Albania to the northwest, North Macedonia and Bulgaria to the north, and Turkey to th ...

the leaves of '' Crepis commutata'' which are called () are eaten raw, boiled, steamed or browned in salads. Another two species on the same island, '' Crepis vesicaria'', called (), () or () and a local variety called () or () have both its leaves and tender shoots eaten boiled by the locals.

Secondary metabolites

The genus ''Crepis'' is a rich source of costus lactone-type guaianolides, a class of

sesquiterpene lactone Sesquiterpene lactones (SLs) are a class of sesquiterpenoids that contain a lactone ring. They are most often found in plants of the family Asteraceae (daisies, asters). Other plant families with SLs are Umbelliferae (celery, parsley, carrots) ...

s. Phenolics found in ''Crepis'' include luteolin-type

flavonoid Flavonoids (or bioflavonoids; from the Latin word ''flavus'', meaning yellow, their color in nature) are a class of polyphenolic secondary metabolites found in plants, and thus commonly consumed in the diets of humans. Chemically, flavonoids ...

s and caffeoyl

quinic acid Quinic acid is an organic compound with the formula . The compound is classified as a cyclitol, a cyclic polyol, and a cyclohexanecarboxylic acid. It is a colorless solid that can be extracted from plant sources. Quinic acid is implicated in the p ...

derivatives such as

chlorogenic acid Chlorogenic acid (CGA) is the ester of caffeic acid and quinic acid, functioning as an intermediate in lignin biosynthesis. The term chlorogenic acids refers to a related polyphenol family of esters, including hydroxycinnamic acids ( caffeic a ...

and 3,5- dicaffeoylquinic acid. Moreover, ''Crepis'' species contain the caffeoyl

tartaric acid Tartaric acid is a white, crystalline organic acid that occurs naturally in many fruits, most notably in grapes but also in tamarinds, bananas, avocados, and citrus. Its salt (chemistry), salt, potassium bitartrate, commonly known as cream of ta ...

derivatives caffeoyl

and cichoric acid.

Diversity

There are about 200 species in the genus. Crepis aurea01

Bombus soroeensis - Crepis tectorum - Keila2

Species include: *'' Crepis acuminata'' – tapertip hawksbeard, longleaf hawk's-beard *'' Crepis alpestris'' *'' Crepis alpina'' *'' Crepis aspera'' *'' Crepis atribarba'' – dark hawk's-beard, slender hawk's-beard *'' Crepis aurea'' – golden hawk's-beard *'' Crepis bakeri'' – Baker's hawksbeard *'' Crepis barbigera'' – bearded hawk's-beard *'' Crepis biennis'' – rough hawksbeard *'' Crepis bungei'' *'' Crepis bursifolia'' – Italian hawksbit *'' Crepis capillaris'' – smooth hawksbeard, green crepis *'' Crepis conyzifolia'' *'' Crepis dioscoridis'' *''

Crepis foetida ''Crepis foetida '' is a European species of flowering plant in the family Asteraceae with the common name stinking hawksbeard. It is widespread across much of Europe and Siberia, as well as being sparingly naturalized in scattered locations in t ...

'' – stinking hawksbeard, roadside hawk's-beard *'' Crepis incana'' – pink dandelion *'' Crepis intermedia'' – limestone hawksbeard, small-flower hawk's-beard *'' Crepis kotschyana'' *'' Crepis micrantha'' *'' Crepis modocensis'' – Modoc hawksbeard, Siskiyou hawksbeard *'' Crepis mollis'' – northern hawksbeard *'' Crepis monticola'' – mountain hawksbeard *'' Crepis nicaeensis'' – French hawksbeard, Turkish hawksbeard *'' Crepis occidentalis'' – largeflower hawksbeard, gray hawk's-beard, western hawk's-beard *'' Crepis palaestina'' *'' Crepis paludosa'' – marsh hawksbeard *'' Crepis pannonica'' – pasture hawksbeard *'' Crepis phoenix'' *'' Crepis pleurocarpa'' – nakedstem hawksbeard, naked hawk's-beard *'' Crepis pontana'' *'' Crepis praemorsa'' – leafless hawksbeard *'' Crepis pulchra'' – small-flower hawk's-beard *'' Crepis pygmaea'' – pygmy hawksbeard *'' Crepis pyrenaica'' *'' Crepis rubra'' – red hawksbeard, pink hawk's-beard *'' Crepis runcinata'' – fiddleleaf hawksbeard *'' Crepis sancta'' – holy hawksbeard *'' Crepis setosa'' – bristly hawksbeard *'' Crepis sibirica'' *'' Crepis sodiroi'' *'' Crepis tectorum'' – narrow-leaved hawksbeard *'' Crepis thompsonii'' *'' Crepis vesicaria'' – beaked hawksbeard, dandelion hawk's-beard, weedy hawk's-beard *'' Crepis zacintha'' – striped hawksbeard

References

External links

USDA Plants Profile of ''Crepis'' species in North AmericaGRIN Species Report on ''Crepis''Flora of China: ''Crepis''
{{Taxonbar, from=Q727610 Asteraceae genera Taxa named by Carl Linnaeus