''Ranunculus'' is a large genus of about 1750

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

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 in the family

Ranunculaceae Ranunculaceae (, buttercup or crowfoot family; Latin "little frog", from "frog") is a family (biology), family of over 2,000 known species of flowering plants in 43 genera, distributed worldwide. The largest genera are ''Ranunculus'' (600 spec ...

. Members of the genus are known as buttercups, spearworts and water crowfoots. The genus is distributed worldwide, primarily in temperate and montane regions. The familiar and widespread buttercup of gardens throughout

Northern Europe The northern region of Europe has several definitions. A restrictive definition may describe northern Europe as being roughly north of the southern coast of the Baltic Sea, which is about 54th parallel north, 54°N, or may be based on other ge ...

(and introduced elsewhere) is the creeping buttercup '' Ranunculus repens'', which has extremely tough and tenacious roots. Two other species are also widespread, the bulbous buttercup '' Ranunculus bulbosus'' and the much taller meadow buttercup '' Ranunculus acris''. In ornamental gardens, all three are often regarded as

weed A weed is a plant considered undesirable in a particular situation, growing where it conflicts with human preferences, needs, or goals.Harlan, J. R., & deWet, J. M. (1965). Some thoughts about weeds. ''Economic botany'', ''19''(1), 16-24. Pla ...

s. Buttercups usually flower in the spring, but flowers may be found throughout the summer, especially where the plants are growing as opportunistic colonizers, as in the case of garden weeds. The water crowfoots (''Ranunculus'' subgenus ''Batrachium''), which grow in still or running water, are sometimes treated in a separate genus ''Batrachium'' (from

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 ...

, "frog"). They have two different leaf types, thread-like leaves underwater and broader floating leaves. In some species, such as '' R. aquatilis'', a third, intermediate leaf type occurs. ''Ranunculus'' species are used as food 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 Hebrew character and

small angle shades The small angle shades (''Euplexia lucipara'') is a moth of the family Noctuidae. It is distributed throughout the Palearctic. The species was first described by Carl Linnaeus in his 1758 10th edition of ''Systema Naturae''. As the common name ...

. Some species are popular ornamental flowers in

horticulture Horticulture (from ) is the art and science of growing fruits, vegetables, flowers, trees, shrubs and ornamental plants. Horticulture is commonly associated with the more professional and technical aspects of plant cultivation on a smaller and mo ...

, with many

cultivar A cultivar is a kind of Horticulture, cultivated plant that people have selected for desired phenotypic trait, traits and which retains those traits when Plant propagation, propagated. Methods used to propagate cultivars include division, root a ...

s selected for large and brightly coloured flowers.

Distribution

Buttercups are found in both hemispheres on all continents aside from Antarctica, and are primarily found in temperate or montane habitats. They likely originated in northern Eurasia during the late

Eocene The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...

Oligocene The Oligocene ( ) is a geologic epoch (geology), epoch of the Paleogene Geologic time scale, Period that extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that defin ...

and rapidly radiated up to the present, dispersing worldwide. Fossil evidence suggests that despite no longer occurring there, they inhabited Antarctica up to the mid-late

Pliocene The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58

Fossil record

''Ranunculus gailensis'' and ''Ranunculus tanaiticus'' seed

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...

s have been described from the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58Rhön Mountains The Rhön Mountains () are a group of low mountains (or ''Mittelgebirge'') in central Germany, located around the border area where the states of Hesse, Bavaria and Thuringia come together. These mountains, which are at the extreme southeast end o ...

, central

Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...

Achene An achene (; ), also sometimes called akene and occasionally achenium or achenocarp, is a type of simple fruit, simple dry fruits, dry fruit produced by many species of flowering plants. Achenes are monocarpellate (formed from one carpel) and Dehi ...

s labelled ''Ranunculus cf. tachiroei'' is known from the Pliocene of the

Hengduan Mountains The Hengduan Mountains () are a group of mountain ranges in southwest China, southwest China that connect the southeast portions of the Tibetan Plateau with the Yunnan–Guizhou Plateau. The Hengduan Mountains are primarily large north-south ...

of China. Indeterminate achenes have been found from

Neogene The Neogene ( ,) is a geologic period and system that spans 20.45 million years from the end of the Paleogene Period million years ago ( Mya) to the beginning of the present Quaternary Period million years ago. It is the second period of th ...

strata from the

Meyer Desert Formation biota The Meyer Desert Formation biota is a fossilized biota (flora and fauna) found in the Dominion Range in the Transantarctic Mountains in Antarctica, alongside the Beardmore Glacier. Since about 15 million years ago (Ma), Antarctica has been most ...

in the

Transantarctic Mountains The Transantarctic Mountains (abbreviated TAM) comprise a mountain range of uplifted rock (primarily sedimentary) in Antarctica which extends, with some interruptions, across the continent from Cape Adare in northern Victoria Land to Coats L ...

, which appear to have inhabited a

periglacial Periglaciation (adjective: "periglacial", referring to places at the edges of glacial areas) describes geomorphic processes that result from seasonal thawing and freezing, very often in areas of permafrost. The meltwater may refreeze in ice wedg ...

environment. The oldest potential fossil is from the Late Eocene (initially identified as Miocene) Florissant Formation of

Colorado Colorado is a U.S. state, state in the Western United States. It is one of the Mountain states, sharing the Four Corners region with Arizona, New Mexico, and Utah. It is also bordered by Wyoming to the north, Nebraska to the northeast, Kansas ...

, identified by

Theodore Dru Alison Cockerell Theodore Dru Alison Cockerell (22 August 1866 – 26 January 1948) was an American entomologist and Systematics, systematic biologist who published nearly 4,000 papers, some of them only a few lines long. Cockerell's speciality was the insect or ...

in 1922.

Description

Plant

Buttercups are mostly

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 ...

, but occasionally annual or biennial,

herbaceous Herbaceous plants are vascular plants that have no persistent woody stems above ground. This broad category of plants includes many perennials, and nearly all annuals and biennials. Definitions of "herb" and "herbaceous" The fourth edition of ...

, aquatic or terrestrial plants, often with leaves in a rosette at the base of the stem. In many perennial species runners are sent out that will develop new plants with roots and rosettes at the distanced nodes. The leaves lack

stipule In botany, a stipule is an outgrowth typically borne on both sides (sometimes on just one side) of the base of a leafstalk (the petiole (botany), petiole). They are primarily found among dicots and rare among monocots. Stipules are considered part ...

s, have petioles, are

palmately veined A leaf (: leaves) is a principal appendage of the plant stem, stem of a vascular plant, usually borne laterally above ground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leav ...

, entire, more or less deeply incised, or compound, and leaflets or leaf segments may be very fine and linear in aquatic species.

Flowers

The hermaphrodite flowers are single or in a cyme, have usually five (but occasionally as few as three or as many as seven)

sepal A sepal () is a part of the flower of angiosperms (flowering plants). Usually green, sepals typically function as protection for the flower in bud, and often as support for the petals when in bloom., p. 106 Etymology The term ''sepalum'' ...

s and usually, five yellow, greenish or white

petal Petals are modified leaves that form an inner whorl surrounding the reproductive parts of flowers. They are often brightly coloured or unusually shaped to attract pollinators. All of the petals of a flower are collectively known as the ''corol ...

s that are sometimes flushed with red, purple or pink (but the petals may be absent or have a different, sometimes much higher number). At the base of each petal is usually one nectary gland that is naked or may be covered by a scale.

Anther The stamen (: stamina or stamens) is a part consisting of the male reproductive organs of a flower. Collectively, the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the filament ...

s may be few, but often many are arranged in a spiral, are yellow or sometimes white, and with yellow

pollen Pollen is a powdery substance produced by most types of flowers of seed plants for the purpose of sexual reproduction. It consists of pollen grains (highly reduced Gametophyte#Heterospory, microgametophytes), which produce male gametes (sperm ...

. The sometimes few but mostly many green or yellow

carpel Gynoecium (; ; : gynoecia) is most commonly used as a collective term for the parts of a flower that produce ovules and ultimately develop into the fruit and seeds. The gynoecium is the innermost whorl of a flower; it consists of (one or more ...

s are not fused and are also arranged in a spiral, mostly on a globe or dome-shaped receptacle.

Reflective petals

The petals of buttercups are often highly lustrous, especially in yellow species, owing to a special coloration mechanism: the petal's upper surface is very smooth causing a mirror-like reflection. The flash aids in attracting pollinating insects and temperature regulation of the flower's reproductive organs. The reflective quality of the buttercup’s petals is mentioned in British folklore; if one holds a buttercup underneath their

chin The chin is the forward pointed part of the anterior mandible (List_of_human_anatomical_regions#Regions, mental region) below the lower lip. A fully developed human skull has a chin of between 0.7 cm and 1.1 cm. Evolution The presence of a we ...

, the light reflecting onto the chin indicates that they like

butter Butter is a dairy product made from the fat and protein components of Churning (butter), churned cream. It is a semi-solid emulsion at room temperature, consisting of approximately 81% butterfat. It is used at room temperature as a spread (food ...

. File:Ranunculus glacialis.jpg, Glacier buttercup ''

Ranunculus glacialis ''Ranunculus'' is a List of the largest genera of flowering plants, large genus of about 1750 species of flowering plants in the family Ranunculaceae. Members of the genus are known as buttercups, spearworts and water crowfoots. The genus is d ...

'' File:Ranunculus glaberrimus 1763f.JPG, Sagebrush buttercup ('' Ranunculus glaberrimus'') File:Ranunculus macro.jpg, Creeping buttercup ('' Ranunculus repens'') File:Heart of gold.JPG, '' Ranunculus asiaticus'', a cultivated form

Fruit

The fruits (in this case called

achene An achene (; ), also sometimes called akene and occasionally achenium or achenocarp, is a type of simple fruit, simple dry fruits, dry fruit produced by many species of flowering plants. Achenes are monocarpellate (formed from one carpel) and Dehi ...

s) may be smooth or hairy, winged, nobby or have hooked spines.

Naming

The genus name ''Ranunculus'' is

Late Latin Late Latin is the scholarly name for the form of Literary Latin of late antiquity.Roberts (1996), p. 537. English dictionary definitions of Late Latin date this period from the 3rd to 6th centuries CE, and continuing into the 7th century in ...

for "little frog", the diminutive of ''rana''. This probably refers to many species being found near water, like frogs. The common name ''buttercup'' may derive from a false belief that the plants give

its characteristic yellow hue (in fact it is poisonous to cows and other livestock). A popular children's game involves holding a buttercup up to the chin; a yellow reflection is supposed to indicate a fondness for butter. In ancient Rome, a species of buttercup was held to the skin by slaves attempting to remove forehead tattoos made by their owners. In the interior of the Pacific Northwest of the United States, the buttercup is called "Coyote's eyes"— in

Nez Perce The Nez Perce (; autonym in Nez Perce language: , meaning 'we, the people') are an Indigenous people of the Plateau who still live on a fraction of the lands on the southeastern Columbia River Plateau in the Pacific Northwest. This region h ...

and in Sahaptin. In the legend,

Coyote The coyote (''Canis latrans''), also known as the American jackal, prairie wolf, or brush wolf, is a species of canis, canine native to North America. It is smaller than its close relative, the Wolf, gray wolf, and slightly smaller than the c ...

was tossing his eyes up in the air and catching them again when Eagle snatched them. Unable to see, Coyote made eyes from the buttercup.

Splitting of the genus

Molecular investigation of the genus has revealed that ''Ranunculus'' is not monophyletic with respect to a number of other recognized genera in the family—e.g. '' Ceratocephala'', '' Halerpestes'', '' Hamadryas'', '' Laccopetalum'', '' Myosurus'', '' Oxygraphis'', '' Paroxygraphis'' and ''

Trautvetteria ''Trautvetteria'' is a genus of flowering plant in the family Ranunculaceae, native from the Russian Far East to Japan, and to the southwestern and south central United States and Mexico. The genus was established in 1835. Species , Plants of t ...

''. A proposal to split ''Ranunculus'' into several genera has thus been published in a 2010 classification for the tribe Ranunculeae. The split (and often re-recognized) genera include '' Arcteranthis'' Greene, '' Beckwithia'' Jeps., '' Callianthemoides'' Tamura, '' Coptidium'' (Prantl) Beurl. ex Rydb., '' Cyrtorhyncha'' Nutt. ex Torr. & A.Gray, '' Ficaria'' Guett., '' Krapfia'' DC., '' Kumlienia'' E. Greene and '' Peltocalathos'' Tamura. Not all taxonomists and users accept this splitting of the genus, and it can alternatively be treated in the broad sense.

Pharmacological activity

The most common uses of ''Ranunculus'' species in traditional medicines are as an antirheumatic, as a

rubefacient A rubefacient is a substance for topical application that produces redness of the skin, e.g. by causing dilation of the capillaries and an increase in blood circulation. It has sometimes been used to relieve acute or chronic pain, but there is limi ...

, and to treat intermittent fever. The findings in some ''Ranunculus'' species of, for example, protoanemonin, anemonin, may justify the uses of these species against fever, rheumatism and rubefacient in Asian traditional medicines.

Toxicity

All ''Ranunculus'' (buttercup) species are

poison A poison is any chemical substance that is harmful or lethal to living organisms. The term is used in a wide range of scientific fields and industries, where it is often specifically defined. It may also be applied colloquially or figurati ...

ous when eaten fresh, but their acrid taste and the blistering of the mouth caused by their poison means they are usually left uneaten. Poisoning in

livestock Livestock are the Domestication, domesticated animals that are raised in an Agriculture, agricultural setting to provide labour and produce diversified products for consumption such as meat, Egg as food, eggs, milk, fur, leather, and wool. The t ...

can occur where buttercups are abundant in overgrazed fields where little other edible plant growth is left, and the animals eat them out of desperation. Symptoms of poisoning include bloody

diarrhea Diarrhea (American English), also spelled diarrhoea or diarrhœa (British English), is the condition of having at least three loose, liquid, or watery bowel movements in a day. It often lasts for a few days and can result in dehydration d ...

, excessive salivation, colic, and severe blistering of the mouth, mucous membranes and gastrointestinal tract. When ''Ranunculus'' plants are handled, naturally occurring

ranunculin Ranunculin is a glycoside found in many members of the Ranunculaceae, buttercup family, including species of Helleborus, Anemone, Clematis and most commonly Ranunculus. Glycosides are common in plants, where they serve as defense mechanisms again ...

is broken down to form protoanemonin, which is known to cause contact

dermatitis Dermatitis is a term used for different types of skin inflammation, typically characterized by itchiness, redness and a rash. In cases of short duration, there may be small blisters, while in long-term cases the skin may become thickened ...

in humans and care should therefore be exercised in extensive handling of the plants. The toxins are degraded by drying, so hay containing dried buttercups is safe.

Species

References

Notes

General sources

External links

* *
All about the ''Ranunculus''

The ''Ranunculus'' home page

The Flower (''Ranunculus'') Fields of Carlsbad, CA
{{Authority control Ranunculaceae genera Taxa named by Carl Linnaeus