Clover
Encyclopedia
Clover or trefoil, is a genus
of about 300 species
of plant
s in the leguminous pea family Fabaceae
. The genus has a cosmopolitan distribution
; the highest diversity is found in the temperate Northern Hemisphere
, but many species also occur in South America
and Africa
, including at high altitudes on mountains in the tropics. They are small annual
, biennial
, or short-lived perennial
herbaceous
plants. The leaves are trifoliate (rarely 5- or 7-foliate), with stipules adnate to the leaf-stalk, and heads or dense spikes of small red, purple, white, or yellow flowers; the small, few-seeded pods are enclosed in the calyx
. Other closely related genera often called clovers include Melilotus (sweet clover) and Medicago
(alfalfa
or 'calvary clover'). The "shamrock
" of popular iconography is sometimes considered to be young clover. The scientific name derives from the Latin
tres, "three", and folium, "leaf", so called from the characteristic form of the leaf, which has three leaflet
s (trifoliate); hence the popular name trefoil
. Clovers are used as food plants by the larva
e of some Lepidoptera
(butterfly
and moth
) species; see list of Lepidoptera that feed on clovers.
. The most widely cultivated clovers are white clover
Trifolium repens and red clover
Trifolium pratense. Clover, either sown alone or in mixture with ryegrass
, has for a long time formed a staple crop for soiling, for several reasons: it grows freely, shooting up again after repeated mowings; it produces an abundant crop; it is palatable to and nutritious for livestock
; it grows in a great range of soil
s and climate
s; and it is appropriate for either pasturage or green composting.
In many areas, particularly on acidic soil, clover is short-lived because of a combination of insect pests, diseases and nutrient balance; this is known as "clover sickness". When crop rotation
s are managed so that clover does not recur at intervals shorter than eight years, it grows with much of its pristine vigor.
Clover sickness in more recent times may also be linked to pollinator decline
; clovers are most efficiently pollinated by bumblebee
s, which have declined as a result of agricultural intensification. Honeybees can also pollinate clover, and beekeeper
s are often in heavy demand from farmers with clover pastures. Farmers reap the benefits of increased reseeding that occurs with increased bee activity, which means that future clover yields remain abundant. Beekeepers benefit from the clover bloom, as clover is one of the main nectar sources for honeybees
.
T. repens, white or Dutch clover, is a perennial abundant in meadows and good pastures. The flowers are white or pinkish, becoming brown and deflexed as the corolla fades. T. hybridum, alsike or Swedish clover, is a perennial which was introduced early in the 19th century and has now become naturalized in Britain. The flowers are white or rosy, and resemble those of the last species. T. medium, meadow or zigzag clover, a perennial with straggling flexuous stems and rose-purple flowers, is of little agricultural value.
Other South African species are: T. arvense, hare's-foot trefoil; found in fields and dry pastures, a soft hairy plant with minute white or pale pink flowers and feathery sepals; T. fragiferum, orange clover, with hot-grounded, globose, rose-purple heads and swollen calyxes; T. procumbens, hop trefoil, on dry pastures and roadsides, the heads of pale yellow flowers suggesting miniature hops; and the somewhat similar T. minus, common in pastures and roadsides, with smaller heads and small yellow flowers turning dark brown. It is a source of high protein.
Shamrock
, the traditional Irish symbol, which according to legend was coined by Saint Patrick
for the Holy Trinity, is commonly associated with clover, though sometimes with Oxalis
species, which are also trifoliate (i.e., they have three leaves).
Clovers occasionally have leaves with four leaflets, instead of the usual three. These four-leaf clover
s, like other rarities, are considered lucky. Clovers can also have five, six, or more leaves, but these are rarer. The record for most leaves is 56, set in 10 May 2009. This beat the 21-leaf clover, a record set in June 2008 by the same man, who had also held the prior record Guinness World Record of 18.
A common idiom
is "to be (live) in clover", meaning to live a carefree life of ease, comfort, or prosperity. This originally referred to the fact that clover is fattening to cattle.
The cloverleaf interchange
is named for the resemblance to the leaves of a (four-leafed) clover when viewed from the air.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of about 300 species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of plant
Plant
Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...
s in the leguminous pea family Fabaceae
Fabaceae
The Fabaceae or Leguminosae, commonly known as the legume, pea, or bean family, is a large and economically important family of flowering plants. The group is the third largest land plant family, behind only the Orchidaceae and Asteraceae, with 730 genera and over 19,400 species...
. The genus has a cosmopolitan distribution
Cosmopolitan distribution
In biogeography, a taxon is said to have a cosmopolitan distribution if its range extends across all or most of the world in appropriate habitats. For instance, the killer whale has a cosmopolitan distribution, extending over most of the world's oceans. Other examples include humans, the lichen...
; the highest diversity is found in the temperate Northern Hemisphere
Northern Hemisphere
The Northern Hemisphere is the half of a planet that is north of its equator—the word hemisphere literally means “half sphere”. It is also that half of the celestial sphere north of the celestial equator...
, but many species also occur in South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
and Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
, including at high altitudes on mountains in the tropics. They are small annual
Annual plant
An annual plant is a plant that usually germinates, flowers, and dies in a year or season. True annuals will only live longer than a year if they are prevented from setting seed...
, biennial
Biennial plant
A biennial plant is a flowering plant that takes two years to complete its biological lifecycle. In the first year the plant grows leaves, stems, and roots , then it enters a period of dormancy over the colder months. Usually the stem remains very short and the leaves are low to the ground, forming...
, or short-lived perennial
Perennial plant
A perennial plant or simply perennial is a plant that lives for more than two years. The term is often used to differentiate a plant from shorter lived annuals and biennials. The term is sometimes misused by commercial gardeners or horticulturalists to describe only herbaceous perennials...
herbaceous
Herbaceous
A herbaceous plant is a plant that has leaves and stems that die down at the end of the growing season to the soil level. They have no persistent woody stem above ground...
plants. The leaves are trifoliate (rarely 5- or 7-foliate), with stipules adnate to the leaf-stalk, and heads or dense spikes of small red, purple, white, or yellow flowers; the small, few-seeded pods are enclosed in the calyx
Flower
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants . The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs...
. Other closely related genera often called clovers include Melilotus (sweet clover) and Medicago
Medicago
Medicago is a genus of flowering plants, commonly known as medick or burclover. The name is based on Latin medica 'alfalfa, lucerne,' from 'Median .'...
(alfalfa
Alfalfa
Alfalfa is a flowering plant in the pea family Fabaceae cultivated as an important forage crop in the US, Canada, Argentina, France, Australia, the Middle East, South Africa, and many other countries. It is known as lucerne in the UK, France, Australia, South Africa and New Zealand, and known as...
or 'calvary clover'). The "shamrock
Shamrock
The shamrock is a three-leafed old white clover. It is known as a symbol of Ireland. The name shamrock is derived from Irish , which is the diminutive version of the Irish word for clover ....
" of popular iconography is sometimes considered to be young clover. The scientific name derives from the Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
tres, "three", and folium, "leaf", so called from the characteristic form of the leaf, which has three leaflet
Leaflet
A leaflet in botany is a part of a compound leaf. A leaflet may resemble an entire leaf, but it is not borne on a stem as a leaf is, but rather on a vein of the whole leaf. Compound leaves are common in many plant families...
s (trifoliate); hence the popular name trefoil
Trefoil
Trefoil is a graphic form composed of the outline of three overlapping rings used in architecture and Christian symbolism...
. Clovers are used as food plants by the larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
e of some Lepidoptera
Lepidoptera
Lepidoptera is a large order of insects that includes moths and butterflies . It is one of the most widespread and widely recognizable insect orders in the world, encompassing moths and the three superfamilies of butterflies, skipper butterflies, and moth-butterflies...
(butterfly
Butterfly
A butterfly is a mainly day-flying insect of the order Lepidoptera, which includes the butterflies and moths. Like other holometabolous insects, the butterfly's life cycle consists of four parts: egg, larva, pupa and adult. Most species are diurnal. Butterflies have large, often brightly coloured...
and moth
Moth
A moth is an insect closely related to the butterfly, both being of the order Lepidoptera. Moths form the majority of this order; there are thought to be 150,000 to 250,000 different species of moth , with thousands of species yet to be described...
) species; see list of Lepidoptera that feed on clovers.
Cultivation
Several species are extensively cultivated as fodder plantsFodder
Fodder or animal feed is any agricultural foodstuff used specifically to feed domesticated livestock such as cattle, goats, sheep, horses, chickens and pigs. Most animal feed is from plants but some is of animal origin...
. The most widely cultivated clovers are white clover
White clover
Trifolium repens, the white clover , is a species of clover native to Europe, North Africa, and West Asia...
Trifolium repens and red clover
Red clover
Trifolium pratense is a species of clover, native to Europe, Western Asia and northwest Africa, but planted and naturalised in many other regions....
Trifolium pratense. Clover, either sown alone or in mixture with ryegrass
Ryegrass
Ryegrass is a genus of nine species of tufted grasses in the Pooideae subfamily of the Poaceae family. Also called tares , these plants are native to Europe, Asia and northern Africa, but are...
, has for a long time formed a staple crop for soiling, for several reasons: it grows freely, shooting up again after repeated mowings; it produces an abundant crop; it is palatable to and nutritious for livestock
Livestock
Livestock refers to one or more domesticated animals raised in an agricultural setting to produce commodities such as food, fiber and labor. The term "livestock" as used in this article does not include poultry or farmed fish; however the inclusion of these, especially poultry, within the meaning...
; it grows in a great range of soil
Soil
Soil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics...
s and climate
Climate
Climate encompasses the statistics of temperature, humidity, atmospheric pressure, wind, rainfall, atmospheric particle count and other meteorological elemental measurements in a given region over long periods...
s; and it is appropriate for either pasturage or green composting.
In many areas, particularly on acidic soil, clover is short-lived because of a combination of insect pests, diseases and nutrient balance; this is known as "clover sickness". When crop rotation
Crop rotation
Crop rotation is the practice of growing a series of dissimilar types of crops in the same area in sequential seasons.Crop rotation confers various benefits to the soil. A traditional element of crop rotation is the replenishment of nitrogen through the use of green manure in sequence with cereals...
s are managed so that clover does not recur at intervals shorter than eight years, it grows with much of its pristine vigor.
Clover sickness in more recent times may also be linked to pollinator decline
Pollinator decline
The term pollinator decline refers to the reduction in abundance of pollinators in many ecosystems worldwide during the end of the twentieth century....
; clovers are most efficiently pollinated by bumblebee
Bumblebee
A bumble bee is any member of the bee genus Bombus, in the family Apidae. There are over 250 known species, existing primarily in the Northern Hemisphere although they are common in New Zealand and in the Australian state of Tasmania.Bumble bees are social insects that are characterised by black...
s, which have declined as a result of agricultural intensification. Honeybees can also pollinate clover, and beekeeper
Beekeeper
A beekeeper is a person who keeps honey bees for the purposes of securing commodities such as honey, beeswax, pollen, royal jelly; pollinating fruits and vegetables; raising queens and bees for sale to other farmers; and/or for purposes satisfying natural scientific curiosity...
s are often in heavy demand from farmers with clover pastures. Farmers reap the benefits of increased reseeding that occurs with increased bee activity, which means that future clover yields remain abundant. Beekeepers benefit from the clover bloom, as clover is one of the main nectar sources for honeybees
Northern Nectar Sources for Honeybees
The nectar source in a given area depends on the type of vegetation present and the length of their bloom period. What type of vegetation will grow in an area depends on soil texture, soil pH, soil drainage, daily maximum and minimum temperatures, precipitation, extreme minimum winter temperature,...
.
T. repens, white or Dutch clover, is a perennial abundant in meadows and good pastures. The flowers are white or pinkish, becoming brown and deflexed as the corolla fades. T. hybridum, alsike or Swedish clover, is a perennial which was introduced early in the 19th century and has now become naturalized in Britain. The flowers are white or rosy, and resemble those of the last species. T. medium, meadow or zigzag clover, a perennial with straggling flexuous stems and rose-purple flowers, is of little agricultural value.
Other South African species are: T. arvense, hare's-foot trefoil; found in fields and dry pastures, a soft hairy plant with minute white or pale pink flowers and feathery sepals; T. fragiferum, orange clover, with hot-grounded, globose, rose-purple heads and swollen calyxes; T. procumbens, hop trefoil, on dry pastures and roadsides, the heads of pale yellow flowers suggesting miniature hops; and the somewhat similar T. minus, common in pastures and roadsides, with smaller heads and small yellow flowers turning dark brown. It is a source of high protein.
Symbolism and mythology
Shamrock
The shamrock is a three-leafed old white clover. It is known as a symbol of Ireland. The name shamrock is derived from Irish , which is the diminutive version of the Irish word for clover ....
, the traditional Irish symbol, which according to legend was coined by Saint Patrick
Saint Patrick
Saint Patrick was a Romano-Briton and Christian missionary, who is the most generally recognized patron saint of Ireland or the Apostle of Ireland, although Brigid of Kildare and Colmcille are also formally patron saints....
for the Holy Trinity, is commonly associated with clover, though sometimes with Oxalis
Oxalis
Oxalis is by far the largest genus in the wood-sorrel family Oxalidaceae: of the approximately 900 known species in the Oxalidaceae, 800 belong here...
species, which are also trifoliate (i.e., they have three leaves).
Clovers occasionally have leaves with four leaflets, instead of the usual three. These four-leaf clover
Four-leaf clover
The four-leaf clover is an uncommon variation of the common, three-leaved clover. According to tradition, such leaves bring good luck to their finders, especially if found accidentally...
s, like other rarities, are considered lucky. Clovers can also have five, six, or more leaves, but these are rarer. The record for most leaves is 56, set in 10 May 2009. This beat the 21-leaf clover, a record set in June 2008 by the same man, who had also held the prior record Guinness World Record of 18.
A common idiom
Idiom
Idiom is an expression, word, or phrase that has a figurative meaning that is comprehended in regard to a common use of that expression that is separate from the literal meaning or definition of the words of which it is made...
is "to be (live) in clover", meaning to live a carefree life of ease, comfort, or prosperity. This originally referred to the fact that clover is fattening to cattle.
The cloverleaf interchange
Cloverleaf interchange
A cloverleaf interchange is a two-level interchange in which left turns, reverse direction in left-driving regions, are handled by ramp roads...
is named for the resemblance to the leaves of a (four-leafed) clover when viewed from the air.
Selected species
The genus Trifolium currently has 245 recognized species:
|
Trifolium fragiferum Trifolium fragiferum is a species of clover known by the common name strawberry clover. It is native to Europe, Asia, and parts of Africa. It is present in other places, such as sections of North America, as an introduced species. It is also cultivated as a cover crop and for hay and silage, as... L. Trifolium fucatum Trifolium fucatum is a species of clover known by the common names bull clover and sour clover. It is native to Oregon and California, where it grows in many types of habitat, becoming common to abundant in some areas. It is an annual herb growing decumbent to erect in form, the stem often... Lindl. Trifolium glomeratum Trifolium glomeratum is a species of clover known by the common names clustered clover and bush clover. It is native to Eurasia and North Africa and it is known elsewhere as an introduced species. It easily takes hold in disturbed areas, becoming a common weed. It is an annual herb growing... L. Trifolium gracilentum Trifolium gracilentum is a species of clover known by the common names pinpoint clover. It is native to western North America including the west coast of the United States and northwestern Mexico, where it grows in many types of habitat, including disturbed areas. It is an annual herb growing... Torr. & A. Gray Trifolium gymnocarpon Trifolium gymnocarpon is a species of clover known by the common name hollyleaf clover. It is native to the western United States, where it can be found in many types of habitat, including sagebrush. It is a small perennial herb with stems spreading along the ground to form a flat mat or clump. The... Nutt. Trifolium hirtum Trifolium hirtum is a species of clover known by the common name rose clover. It is native to Europe, Western Asia, and North Africa. It is present elsewhere as an introduced species and it is cultivated as a cover crop and animal fodder... All. Trifolium howellii Trifolium howellii is a species of clover known by the common names canyon clover and Howell's clover. It is native to Oregon and California, where it grows in moist and shady habitat types, such as swamps and forest streambanks.-Description:... S. Watson Trifolium hybridum Trifolium hybridum, alsike clover, is a plant species of the genus Trifolium in the pea family Fabaceae. The stalked, pale pink or whitish flower head grows from the leaf axils, and the trifoliate leaves are unmarked. The plant is tall, and is found in fields and on roadsides – it is also... L., Alsike Clover Trifolium jokerstii Trifolium jokerstii is a rare species of clover known by the common names Butte County golden clover and Jim's clover. It is endemic to Butte County, California, where it is known from eight or nine occurrences near Oroville. It grows in seasonally moist habitat, such as vernal pools, pastures, and... Vincent & Rand. Morgan Trifolium lemmonii Trifolium lemmonii is a species of clover known by the common name Lemmon's clover. It is native to the Sierra Nevada of California, its distribution extending just into Nevada. It is a resident of the coniferous forests and sagebrush of the high mountains. It is a perennial herb spreading to form... S. Watson Trifolium longipes Trifolium longipes is a species of clover known by the common name longstalk clover. It is native to the western United States, where it occurs in many types of habitat. There are many subtaxa which occur in different regions and differ slightly in appearance... Nutt. Trifolium macraei Trifolium macraei is a species of clover known by the common names Chilean clover, double-head clover, and MacRae's clover. It has a disjunct distribution, occurring on the coastline of Oregon and California in the United States, as well as in South America. It grows in coastal habitat, such as... Hook. & Arn. Trifolium macrocephalum Trifolium macrocephalum is a species of clover known by the common name largehead clover. It is native to the northwestern United States from Washington to northern California to Idaho, where it occurs in several types of habitat, including sagebrush and mountain woodlands. It is a rhizomatous... (Pursh) Poir. Trifolium medium Trifolium medium or Zigzag Clover is a plant species of the genus Trifolium.* quattrofolium... L. Trifolium microcephalum Trifolium microcephalum is a species of clover known by the common name smallhead clover. It is native to western North America from southern Alaska and British Columbia to California and Arizona, where it occurs in many types of habitat, becoming common to abundant in some regions. It can grow in... Pursh Trifolium microdon Trifolium microdon is a species of clover known by the common name thimble clover. It is native to western North America from British Columbia to southern California, where it grows in many types of habitat, including disturbed areas. It is an annual herb taking a decumbent or erect form. It is... Hook. & Arn. Trifolium monanthum Trifolium monanthum is a species of clover known by the common name mountain carpet clover. It is native to the mountains of southern and eastern California and western Nevada, where it occurs at elevations above 1500 meters in coniferous forests, woodlands, and meadows. It is a small perennial... A. Gray Trifolium montanum Trifolium montanum is a plant species of the genus Trifolium. It is the county flower of Oslo, Norway.-References:*... L. Trifolium nigrescens Trifolium nigrescens, a member of the clover genus, it is an annual species which is widespread around the Mediterranean, including north Africa, and the Middle East.... Viv. Trifolium obtusiflorum Trifolium obtusiflorum is a species of clover known by the common name clammy clover. It is native to California in the Peninsular, Transverse, Sierra Nevada, and the California Coast Ranges and Cascade Range into southwestern Oregon.... Hook. & Arn. Trifolium oliganthum Trifolium oliganthum is a species of clover known by the common name fewflower clover. It is native to western coastal and montane North America from British Columbia to California, the Sierra Nevada, and to Baja California, where it occurs in many types of habitat.-Description:Trifolium oliganthum... Steud. |
Trifolium pignantii Trifolium pignantii is a species of clover in the pea family Fabaceae, native to Albania, Bulgaria,; the former Yugoslavia, and Greece.- References :* * * J. B. G. M. Bory de Saint-Vincent et al., Exp. sci. Morée, Bot. 3:219. 1832.... Brongn. & Bory Shamrock The shamrock is a three-leafed old white clover. It is known as a symbol of Ireland. The name shamrock is derived from Irish , which is the diminutive version of the Irish word for clover .... (white clover) Trifolium resupinatum Trifolium resupinatum is an annual clover used as fodder and hay, which reaches tall when cultivated, and forms rosettes when grazed or mowed. It is native to central and southern Europe, the Mediterranean, and southwest Asia as far south as the Punjab... L. Trifolium striatum Trifolium striatum or Knotted Clover is a plant species of the genus Trifolium.... L. Trifolium trichocalyx Trifolium trichocalyx is a species of clover known by the common name Monterey clover.-Distribution:Trifolium trichocalyx is endemic to Monterey County, California, where it is known only from the Monterey Peninsula.... A. Heller Trifolium variegatum Trifolium variegatum is a species of clover known by the common name whitetip clover. It is native to western North America from southern Alaska and British Columbia to Baja California, where it occurs in many types of habitat.-Description:... Nutt. Trifolium willdenovii Trifolium willdenovii, or Tomcat clover, is a species of plant in the pea family Fabaceae. This species occurs in the western part of North America. As an example occurrence, it is found in the California Coast Ranges in such places as Ring Mountain, California, where it is found in association... Spreng., Tomcat clover Trifolium wormskioldii The legume Trifolium wormskioldii is a species of clover native to the western half of North America. Its common names include cow clover, coast clover and springbank clover... Lehm. Johann Georg Christian Lehmann Johann Georg Christian Lehmann was a German botanist.Born at Haselau, near Uetersen, Holstein, Lehmann studied medicine in Copenhagen and Göttingen, obtained a doctorate in medicine in 1813 and a doctorate in philosophy from he University of Jena in 1814... , Cow clover |
See also
- Cloverleaf quasarCloverleaf quasarThe Cloverleaf quasar is a bright, gravitationally-lensed quasar.- Quasar :Molecular gas detected in the host galaxy associated with the quasar is the oldest molecular material known and provides evidence of large-scale star formation in the early universe.Thanks to the strong magnification...
- Cloverleaf interchangeCloverleaf interchangeA cloverleaf interchange is a two-level interchange in which left turns, reverse direction in left-driving regions, are handled by ramp roads...
- Four-leaf cloverFour-leaf cloverThe four-leaf clover is an uncommon variation of the common, three-leaved clover. According to tradition, such leaves bring good luck to their finders, especially if found accidentally...
- Sweet clover
External links
- Edibility of clover: Edible parts and visual identification of wild clover.
- http://msucares.com/news/print/agnews/an04/040311.html Nitrogen fixation