Root

Root

Overview

In vascular plant
Vascular plant
Vascular plants are those plants that have lignified tissues for conducting water, minerals, and photosynthetic products through the plant. Vascular plants include the clubmosses, Equisetum, ferns, gymnosperms and angiosperms...

s, the root is the organ of a plant that typically lies below the surface of the soil. This is not always the case, however, since a root can also be aerial
Aerial root
Aerial roots are roots above the ground. They are almost always adventitious. They are found in diverse plant species, including epiphytes such as orchids, tropical coastal swamp trees such as mangroves, the resourceful banyan trees, the warm-temperate rainforest rātā and pōhutukawa Aerial roots...

 (growing above the ground) or aerating (growing up above the ground or especially above water). Furthermore, a stem normally occurring below ground is not exceptional either (see rhizome
Rhizome
In botany and dendrology, a rhizome is a characteristically horizontal stem of a plant that is usually found underground, often sending out roots and shoots from its nodes...

). So, it is better to define root as a part of a plant body that bears no leaves, and therefore also lacks nodes.
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In vascular plant
Vascular plant
Vascular plants are those plants that have lignified tissues for conducting water, minerals, and photosynthetic products through the plant. Vascular plants include the clubmosses, Equisetum, ferns, gymnosperms and angiosperms...

s, the root is the organ of a plant that typically lies below the surface of the soil. This is not always the case, however, since a root can also be aerial
Aerial root
Aerial roots are roots above the ground. They are almost always adventitious. They are found in diverse plant species, including epiphytes such as orchids, tropical coastal swamp trees such as mangroves, the resourceful banyan trees, the warm-temperate rainforest rātā and pōhutukawa Aerial roots...

 (growing above the ground) or aerating (growing up above the ground or especially above water). Furthermore, a stem normally occurring below ground is not exceptional either (see rhizome
Rhizome
In botany and dendrology, a rhizome is a characteristically horizontal stem of a plant that is usually found underground, often sending out roots and shoots from its nodes...

). So, it is better to define root as a part of a plant body that bears no leaves, and therefore also lacks nodes. There are also important internal structural differences between stems and roots.

The first root that comes from a 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...

 is called the radicle
Radicle
In botany, the radicle is the first part of a seedling to emerge from the seed during the process of germination. The radicle is the embryonic root of the plant, and grows downward in the soil...

. The four major functions of roots are 1) absorption of water and inorganic nutrients, 2) anchoring of the plant body to the ground and 3) storage of food and nutrients and 4) to prevent soil erosion. In response to the concentration of nutrients, roots also synthesise cytokinin
Cytokinin
Cytokinins are a class of plant growth substances that promote cell division, or cytokinesis, in plant roots and shoots. They are involved primarily in cell growth and differentiation, but also affect apical dominance, axillary bud growth, and leaf senescence...

, which acts as a signal as to how fast the shoots can grow. Roots often function in storage of food and nutrients. The roots of most vascular plant species enter into symbiosis with certain fungi to form mycorrhiza
Mycorrhiza
A mycorrhiza is a symbiotic association between a fungus and the roots of a vascular plant....

s, and a large range of other organisms including bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...

 also closely associate with roots.

Anatomy


When dissected, the arrangement of the cells in a root is root hair
Root hair
A root hair, the rhizoid of a vascular plant, is a tubular outgrowth of a trichoblast, a hair-forming cell on the epidermis of a plant root. That is, root hairs are lateral extensions of a single cell and only rarely branched, thus invisible to the naked eye. They are found only in the region of...

, epidermis
Epidermis (botany)
The epidermis is a single-layered group of cells that covers plants' leaves, flowers, roots and stems. It forms a boundary between the plant and the external environment. The epidermis serves several functions, it protects against water loss, regulates gas exchange, secretes metabolic compounds,...

, epiblem
Epiblem
In botany, Epiblem is a tissue that replaces the epidermis in most roots and in stems of submerged aquatic plants. It is usually located between the epidermis and cortex in the root or stem of a plant....

, cortex
Cortex (botany)
In botany, the cortex is the outer layer of the stem or root of a plant, bounded on the outside by the epidermis and on the inside by the endodermis. It is composed mostly of undifferentiated cells, usually large thin-walled parenchyma cells of the ground tissue system. The outer cortical cells...

, endodermis
Endodermis
The endodermis is the central, innermost layer of cortex in some land plants. It is made of compact living cells surrounded by an outer ring of endodermal cells that are impregnated with hydrophobic substances to restrict apoplastic flow of water to the inside...

, pericycle
Pericycle
The pericycle is a cylinder of parenchyma cells that lies just inside the endodermis and is the outer most part of the stele of plants.Although it is composed of non-vascular parenchyma cells, it is still considered part of the vascular cylinder because it arises from the procambium as do the...

 and lastly the vascular tissue
Vascular tissue
Vascular tissue is a complex conducting tissue, formed of more than one cell type, found in vascular plants. The primary components of vascular tissue are the xylem and phloem. These two tissues transport fluid and nutrients internally. There are also two meristems associated with vascular tissue:...

 in the centre of a root to transport the water absorbed by the root to other places of the plant.

Root growth



Early root growth is one of the functions of the apical meristem located near the tip of the root. The meristem cells more or less continuously divide, producing more meristem, root cap
Root cap
The root cap is a section of tissue at the tip of a plant root. It is also called calyptra. Root caps contain statocytes which are involved in gravity perception in plants. If the cap is carefully removed the root will grow randomly. The root cap protects the growing tip in plants...

 cells (these are sacrificed to protect the meristem), and undifferentiated root cells. The latter become the primary tissues of the root, first undergoing elongation, a process that pushes the root tip forward in the growing medium. Gradually these cells differentiate and mature into specialized cells of the root tissues.

Roots will generally grow in any direction where the correct environment of air
Earth's atmosphere
The atmosphere of Earth is a layer of gases surrounding the planet Earth that is retained by Earth's gravity. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention , and reducing temperature extremes between day and night...

, mineral nutrients and water
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...

 exists to meet the plant's needs. Roots will not grow in dry soil. Over time, given the right conditions, roots can crack foundations, snap water lines, and lift sidewalks. At germination
Germination
Germination is the process in which a plant or fungus emerges from a seed or spore, respectively, and begins growth. The most common example of germination is the sprouting of a seedling from a seed of an angiosperm or gymnosperm. However the growth of a sporeling from a spore, for example the...

, roots grow downward due to gravitropism
Gravitropism
Gravitropism is a turning or growth movement by a plant or fungus in response to gravity. Charles Darwin was one of the first to scientifically document that roots show positive gravitropism and stems show negative gravitropism. That is, roots grow in the direction of gravitational pull and stems...

, the growth mechanism of plants that also causes the shoot to grow upward. In some plants (such as ivy
Ivy
Ivy, plural ivies is a genus of 12–15 species of evergreen climbing or ground-creeping woody plants in the family Araliaceae, native to western, central and southern Europe, Macaronesia, northwestern Africa and across central-southern Asia east to Japan and Taiwan.-Description:On level ground they...

), the "root" actually clings to walls and structures.

Growth from apical meristems is known as primary growth, which encompasses all elongation. Secondary growth encompasses all growth in diameter, a major component of woody plant
Woody plant
A woody plant is a plant that uses wood as its structural tissue. These are typically perennial plants whose stems and larger roots are reinforced with wood produced adjacent to the vascular tissues. The main stem, larger branches, and roots of these plants are usually covered by a layer of...

 tissues and many nonwoody plants. For example, storage roots of sweet potato
Sweet potato
The sweet potato is a dicotyledonous plant that belongs to the family Convolvulaceae. Its large, starchy, sweet-tasting, tuberous roots are an important root vegetable. The young leaves and shoots are sometimes eaten as greens. Of the approximately 50 genera and more than 1,000 species of...

 have secondary growth but are not woody. Secondary growth occurs at the lateral meristems, namely the vascular cambium
Vascular cambium
The vascular cambium is a part of the morphology of plants. It consists of cells that are partly specialized, for the tissues that transport water solutions, but have not reached any of the final forms that occur in their branch of the specialization graph...

 and cork cambium
Cork cambium
Cork cambium is a tissue found in many vascular plants as part of the periderm. The cork cambium is a lateral meristem and is responsible for secondary growth that replaces the epidermis in roots and stems...

. The former forms secondary xylem and secondary phloem, while the latter forms the periderm.

In plants with secondary growth, the vascular cambium, originating between the xylem and the phloem, forms a cylinder
Cylinder (geometry)
A cylinder is one of the most basic curvilinear geometric shapes, the surface formed by the points at a fixed distance from a given line segment, the axis of the cylinder. The solid enclosed by this surface and by two planes perpendicular to the axis is also called a cylinder...

 of tissue along the stem
Plant stem
A stem is one of two main structural axes of a vascular plant. The stem is normally divided into nodes and internodes, the nodes hold buds which grow into one or more leaves, inflorescence , conifer cones, roots, other stems etc. The internodes distance one node from another...

 and root. The vascular cambium forms new cells on both the inside and outside of the cambium cylinder, with those on the inside forming secondary xylem cells, and those on the outside forming secondary phloem cells. As secondary xylem accumulates, the "girth" (lateral dimensions) of the stem and root increases. As a result, tissues beyond the secondary phloem (including the epidermis and cortex, in many cases) tend to be pushed outward and are eventually "sloughed off" (shed).

At this point, the cork cambium begins to form the periderm, consisting of protective cork
Cork (material)
Cork is an impermeable, buoyant material, a prime-subset of bark tissue that is harvested for commercial use primarily from Quercus suber , which is endemic to southwest Europe and northwest Africa...

 cells containing suberin. In roots, the cork cambium originates in the pericycle
Pericycle
The pericycle is a cylinder of parenchyma cells that lies just inside the endodermis and is the outer most part of the stele of plants.Although it is composed of non-vascular parenchyma cells, it is still considered part of the vascular cylinder because it arises from the procambium as do the...

, a component of the vascular cylinder.

The vascular cambium produces new layers of secondary xylem annually. The xylem vessels are dead at maturity but are responsible for most water transport through the vascular tissue in stems and roots.

Types of roots



A true root system consists of a primary root and secondary roots (or lateral roots
Lateral roots
Lateral roots extend horizontally from the primary root and serve to anchor the plant securely into the soil. This branching of roots also contributes to water uptake, and facilitates the extraction of nutrients required for the growth and development of the plant.Many different factors are...

).
  • the diffuse root system: the primary root is not dominant; the whole root system is fibrous and branches in all directions. Most common in monocots. The main function of the fibrous root is to anchor the plant.

Specialized roots



The roots, or parts of roots, of many plant species have become specialized to serve adaptive purposes besides the two primary functions described in the introduction.
  • Adventitious roots arise out-of-sequence from the more usual root formation of branches of a primary root, and instead originate from the stem, branches, leaves, or old woody roots. They commonly occur in monocots and pteridophytes, but also in many dicots, such as clover
    Clover
    Clover , or trefoil, is a genus of about 300 species of plants 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...

     (Trifolium), ivy
    Ivy
    Ivy, plural ivies is a genus of 12–15 species of evergreen climbing or ground-creeping woody plants in the family Araliaceae, native to western, central and southern Europe, Macaronesia, northwestern Africa and across central-southern Asia east to Japan and Taiwan.-Description:On level ground they...

     (Hedera), strawberry
    Strawberry
    Fragaria is a genus of flowering plants in the rose family, Rosaceae, commonly known as strawberries for their edible fruits. Although it is commonly thought that strawberries get their name from straw being used as a mulch in cultivating the plants, the etymology of the word is uncertain. There...

     (Fragaria) and willow
    Willow
    Willows, sallows, and osiers form the genus Salix, around 400 species of deciduous trees and shrubs, found primarily on moist soils in cold and temperate regions of the Northern Hemisphere...

     (Salix). Most aerial roots and stilt roots are adventitious. In some conifers adventitious roots can form the largest part of the root system.
  • Aerating roots (or knee root or knee or pneumatophores or Cypress knee
    Cypress knee
    In the biology of trees, a cypress knee is a distinctive structure in a root of a cypress tree of any of various species of the subfamily Taxodioideae. Their function is unknown, but they are generally seen in swamps...

    ): roots rising above the ground, especially above water such as in some mangrove
    Mangrove
    Mangroves are various kinds of trees up to medium height and shrubs that grow in saline coastal sediment habitats in the tropics and subtropics – mainly between latitudes N and S...

     genera (Avicennia
    Avicennia
    Avicennia is a genus of flowering plants currently placed in the bear's breeches family, Acanthaceae. It contains mangrove trees, which occur in the intertidal zones of estuarine areas and are characterized by aerial roots. Species of Avicennia occur worldwide south of the Tropic of Cancer.The...

    , Sonneratia
    Sonneratia
    Sonneratia is a genus of plants in the family Lythraceae. Formerly the Sonneratia were placed in a family called Sonneratiaceae which included both the Sonneratia and the Duabanga, but these two are now placed in their own monotypic subfamilies of the family Lythraceae...

    ). In some plants like Avicennia the erect roots have a large number of breathing pores for exchange of gases.
  • Aerial roots: roots entirely above the ground, such as in ivy (Hedera) or in epiphytic
    Epiphyte
    An epiphyte is a plant that grows upon another plant non-parasitically or sometimes upon some other object , derives its moisture and nutrients from the air and rain and sometimes from debris accumulating around it, and is found in the temperate zone and in the...

     orchids. They function as prop roots, as in maize
    Maize
    Maize known in many English-speaking countries as corn or mielie/mealie, is a grain domesticated by indigenous peoples in Mesoamerica in prehistoric times. The leafy stalk produces ears which contain seeds called kernels. Though technically a grain, maize kernels are used in cooking as a vegetable...

     or anchor roots or as the trunk in strangler fig
    Strangler Fig
    Strangler fig is the common name for a number of tropical and subtropical plant species, including some banyans and unrelated vines, including among many other species:* Ficus aurea, also known as the Florida Strangler Fig...

    .
  • Contractile roots: they pull bulbs or corms of monocots, such as hyacinth and lily, and some taproot
    Taproot
    A taproot is an enlarged, somewhat straight to tapering plant root that grows vertically downward. It forms a center from which other roots sprout laterally.Plants with taproots are difficult to transplant...

    s, such as dandelion, deeper in the soil through expanding radially and contracting longitudinally. They have a wrinkled surface.
  • Coarse roots: Roots that have undergone secondary thickening and have a woody structure. These roots have some ability to absorb water and nutrients, but their main function is transport and to provide a structure to connect the smaller diameter, fine roots to the rest of the plant.
  • Fine roots: Primary roots usually <2 mm diameter that have the function of water and nutrient uptake. They are often heavily branched and support mycorrhizas. These roots may be short lived, but are replaced by the plant in an ongoing process of root 'turnover'.
  • Haustorial roots: roots of parasitic plants that can absorb water and nutrients from another plant, such as in mistletoe
    Mistletoe
    Mistletoe is the common name for obligate hemi-parasitic plants in several families in the order Santalales. The plants in question grow attached to and within the branches of a tree or shrub.-Mistletoe in the genus Viscum:...

     (Viscum album) and dodder.
  • Propagative roots: roots that form adventitious buds that develop into aboveground shoots, termed suckers
    Basal shoot
    A basal shoot, root sprout, adventitious shoot, water sprout or sucker is a shoot or cane which grows from a bud at the base of a tree or shrub or from its roots. This shoot then becomes, or takes the form of, a singular plant. A plant that produces suckers is referred to as surculose...

    , which form new plants, as in Canada thistle, cherry
    Cherry
    The cherry is the fruit of many plants of the genus Prunus, and is a fleshy stone fruit. The cherry fruits of commerce are usually obtained from a limited number of species, including especially cultivars of the wild cherry, Prunus avium....

     and many others.
  • Proteoid root
    Proteoid root
    Proteoid roots, also known as cluster roots, are plant roots that form clusters of closely spaced short lateral rootlets. They may form a two to five centimetre thick mat just beneath the leaf litter. They enhance nutrient uptake, possibly by chemically modifying the soil environment to improve...

    s
    or cluster roots: dense clusters of rootlets of limited growth that develop under low phosphate
    Phosphate
    A phosphate, an inorganic chemical, is a salt of phosphoric acid. In organic chemistry, a phosphate, or organophosphate, is an ester of phosphoric acid. Organic phosphates are important in biochemistry and biogeochemistry or ecology. Inorganic phosphates are mined to obtain phosphorus for use in...

     or low iron
    Iron
    Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...

     conditions in Proteaceae
    Proteaceae
    Proteaceae is a family of flowering plants distributed in the Southern Hemisphere. The family comprises about 80 genera with about 1600 species. Together with the Platanaceae and Nelumbonaceae they make up the order Proteales. Well known genera include Protea, Banksia, Embothrium, Grevillea,...

     and some plants from the following families Betulaceae
    Betulaceae
    Betulaceae, or the Birch Family, includes six genera of deciduous nut-bearing trees and shrubs, including the birches, alders, hazels, hornbeams and hop-hornbeams, numbering about 130 species...

    , Casuarinaceae
    Casuarinaceae
    Casuarinaceae is a family of dicotyledonous flowering plants placed in the order Fagales, consisting of 3 or 4 genera and approximately 70 species of trees and shrubs native to the Old World tropics , Australia, and the Pacific Islands...

    , Elaeagnaceae
    Elaeagnaceae
    Elaeagnaceae, the oleaster family, is a plant family of the order Rosales comprising small trees and shrubs, native to temperate regions of the Northern Hemisphere, south into tropical Asia and Australia. The family has 45-50 species in three genera....

    , Moraceae
    Moraceae
    Moraceae — often called the mulberry family or fig family — are a family of flowering plants comprising about 40 genera and over 1000 species. Most are widespread in tropical and subtropical regions, less so in temperate climates...

    , 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...

     and Myricaceae
    Myricaceae
    The Myricaceae is a small family of dicotyledonous shrubs and small trees in the order Fagales. There are three genera in the family, although some botanists separate many species from Myrica into a fourth genus Morella...

    .
  • Stilt roots: these are adventitious support roots, common among mangrove
    Mangrove
    Mangroves are various kinds of trees up to medium height and shrubs that grow in saline coastal sediment habitats in the tropics and subtropics – mainly between latitudes N and S...

    s. They grow down from lateral branches, branching in the soil.
  • Storage roots: these roots are modified for storage of food or water, such as carrot
    Carrot
    The carrot is a root vegetable, usually orange in colour, though purple, red, white, and yellow varieties exist. It has a crisp texture when fresh...

    s and beet
    Beet
    The beet is a plant in the Chenopodiaceae family which is now included in Amaranthaceae family. It is best known in its numerous cultivated varieties, the most well known of which is the purple root vegetable known as the beetroot or garden beet...

    s. They include some taproot
    Taproot
    A taproot is an enlarged, somewhat straight to tapering plant root that grows vertically downward. It forms a center from which other roots sprout laterally.Plants with taproots are difficult to transplant...

    s and tuberous roots.
  • Structural roots: large roots that have undergone considerable secondary thickening and provide mechanical support to woody plants and trees.
  • Surface roots: These proliferate close below the soil surface, exploiting water and easily available nutrients. Where conditions are close to optimum in the surface layers of soil, the growth of surface roots is encouraged and they commonly become the dominant roots.
  • Tuberous roots: A portion of a root swells for food or water storage, e.g. sweet potato
    Sweet potato
    The sweet potato is a dicotyledonous plant that belongs to the family Convolvulaceae. Its large, starchy, sweet-tasting, tuberous roots are an important root vegetable. The young leaves and shoots are sometimes eaten as greens. Of the approximately 50 genera and more than 1,000 species of...

    . A type of storage root distinct from taproot.

Rooting depths



The distribution of vascular plant roots within soil depends on plant form, the spatial and temporal availability of water and nutrients, and the physical properties of the soil. The deepest roots are generally found in deserts and temperate coniferous forests; the shallowest in tundra, boreal forest and temperate grasslands. The deepest observed living root, at least 60 m below the ground surface, was observed during the excavation of an open-pit mine in Arizona, USA. Some roots can grow as deep as the tree is high. The majority of roots on most plants are however found relatively close to the surface where nutrient availability and aeration are more favourable for growth. Rooting depth may be physically restricted by rock or compacted soil close below the surface, or by anaerobic soil conditions.

Rooting Depth Records

Species Location Maximum rooting depth (m) References
Boscia albitrunca
Boscia albitrunca
Boscia albitrunca, commonly called Witgatboom, Matoppie, or Shepherd's Tree, grows up to 10 metres tall but usually much smaller. It is an evergreen tree native to Southern and Tropical Africa, living in the hot, dry, and often brackish low-lying areas, sometimes on abundant lime and occasionally...

Kalahari desert 68 Jennings (1974)
Juniperus monosperma
Juniperus monosperma
Juniperus monosperma is a species of juniper native to western North America, in the United States in Arizona, New Mexico, southern Colorado, western Oklahoma , and western Texas, and in Mexico in the extreme north of Chihuahua...

Colorado Plateau 61 Cannon (1960)
Eucalyptus
Eucalyptus
Eucalyptus is a diverse genus of flowering trees in the myrtle family, Myrtaceae. Members of the genus dominate the tree flora of Australia...

sp.
Australian forest 61 Jennings (1971)
Acacia erioloba
Acacia erioloba
Acacia erioloba is also commonly known as the Camel Thorn, Kameeldoring , Giraffe Thorn or Mokala . The Mokala National Park in the Northern Cape is named after this tree. The type specimen of Acacia giraffae, proved on closer examination to be a hybrid of A. haematoxylon and the species which...

Kalahari desert 60 Jennings (1974)
Prosopis juliflora
Prosopis juliflora
Prosopis juliflora is a shrub or small tree native to Mexico, South America and the Caribbean. It has become established as a weed in Asia, Australia and elsewhere. Its uses include forage, wood and environmental management. The tree grows to a height of up to and has a trunk with a diameter of...

Arizona desert 53.3 Phillips (1963)

Root architecture



The pattern of development of a root system is termed root architecture, and is important in providing a plant with a secure supply of nutrients and water as well as anchorage and support. The architecture of a root system can be considered in a similar way to above-ground architecture of a plant—i.e. in terms of the size, branching and distribution of the component parts. In roots, the architecture of fine roots and coarse roots can both be described by variation in topology and distribution of biomass within and between roots. Having a balanced architecture allows fine roots to exploit soil efficiently around a plant, but the plastic nature of root growth allows the plant to then concentrate its resources where nutrients and water are more easily available. A balanced coarse root architecture, with roots distributed relatively evenly around the stem base, is necessary to provide support to larger plants and trees.

Tree roots normally grow outward to about three times the branch spread. Only half of a tree's root system occurs between the trunk and the circumference of its canopy. Roots on one side of a tree normally supply the foliage on that same side of the tree. Thus when roots on one side of a tree are injured, the branches and leaves on that same side of the tree may die or wilt. For some trees however, such as the maple
Maple
Acer is a genus of trees or shrubs commonly known as maple.Maples are variously classified in a family of their own, the Aceraceae, or together with the Hippocastanaceae included in the family Sapindaceae. Modern classifications, including the Angiosperm Phylogeny Group system, favour inclusion in...

 family, the effect of a root injury may show itself anywhere in the tree canopy.

Evolutionary history



The fossil record of roots – or rather, infilled voids where roots rotted after death – spans back to the late Silurian, but their identification is difficult, because casts and molds of roots are so similar in appearance to animal burrows – although they can be discriminated on the basis of a range of features.

Economic importance



The term root crops refers to any edible underground plant structure, but many root crops are actually stems, such as potato
Potato
The potato is a starchy, tuberous crop from the perennial Solanum tuberosum of the Solanaceae family . The word potato may refer to the plant itself as well as the edible tuber. In the region of the Andes, there are some other closely related cultivated potato species...

 tubers. Edible roots include cassava
Cassava
Cassava , also called yuca or manioc, a woody shrub of the Euphorbiaceae native to South America, is extensively cultivated as an annual crop in tropical and subtropical regions for its edible starchy tuberous root, a major source of carbohydrates...

, sweet potato
Sweet potato
The sweet potato is a dicotyledonous plant that belongs to the family Convolvulaceae. Its large, starchy, sweet-tasting, tuberous roots are an important root vegetable. The young leaves and shoots are sometimes eaten as greens. Of the approximately 50 genera and more than 1,000 species of...

, beet
Beet
The beet is a plant in the Chenopodiaceae family which is now included in Amaranthaceae family. It is best known in its numerous cultivated varieties, the most well known of which is the purple root vegetable known as the beetroot or garden beet...

, carrot
Carrot
The carrot is a root vegetable, usually orange in colour, though purple, red, white, and yellow varieties exist. It has a crisp texture when fresh...

, rutabaga
Rutabaga
The rutabaga, swede , turnip or yellow turnip is a root vegetable that originated as a cross between the cabbage and the turnip; see Triangle of U...

, turnip
Turnip
The turnip or white turnip is a root vegetable commonly grown in temperate climates worldwide for its white, bulbous taproot. Small, tender varieties are grown for human consumption, while larger varieties are grown as feed for livestock...

, parsnip
Parsnip
The parsnip is a root vegetable related to the carrot. Parsnips resemble carrots, but are paler than most carrots and have a sweeter taste, especially when cooked. The buttery, slightly spicy, sweet flavor of cooked mature parsnips is reminiscent of butterscotch, honey, and subtle cardamom...

, radish
Radish
The radish is an edible root vegetable of the Brassicaceae family that was domesticated in Europe, in pre-Roman times. They are grown and consumed throughout the world. Radishes have numerous varieties, varying in size, color and duration of required cultivation time...

, yam
Yam (vegetable)
Yam is the common name for some species in the genus Dioscorea . These are perennial herbaceous vines cultivated for the consumption of their starchy tubers in Africa, Asia, Latin America and Oceania...

 and horseradish
Horseradish
Horseradish is a perennial plant of the Brassicaceae family, which also includes mustard, wasabi, broccoli, and cabbages. The plant is probably native to south eastern Europe and the Arab World , but is popular around the world today...

. Spices obtained from roots include sassafras
Sassafras
Sassafras is a genus of three extant and one extinct species of deciduous trees in the family Lauraceae, native to eastern North America and eastern Asia.-Overview:...

, angelica
Angelica
Angelica is a genus of about 60 species of tall biennial and perennial herbs in the family Apiaceae, native to temperate and subarctic regions of the Northern Hemisphere, reaching as far North as Iceland and Lapland...

, sarsaparilla
Sarsaparilla
is a perennial trailing vine with prickly stems that is native to Central America. Common names include Sarsaparilla , Honduran Sarsaparilla, and Jamaican Sarsaparilla...

 and licorice.

Sugar beet
Sugar beet
Sugar beet, a cultivated plant of Beta vulgaris, is a plant whose tuber contains a high concentration of sucrose. It is grown commercially for sugar production. Sugar beets and other B...

 is an important source of sugar. Yam
Yam (vegetable)
Yam is the common name for some species in the genus Dioscorea . These are perennial herbaceous vines cultivated for the consumption of their starchy tubers in Africa, Asia, Latin America and Oceania...

 roots are a source of estrogen compounds used in birth control pills. The fish poison and insecticide rotenone
Rotenone
Rotenone is an odorless chemical that is used as a broad-spectrum insecticide, piscicide, and pesticide. It occurs naturally in the roots and stems of several plants such as the jicama vine plant...

 is obtained from roots of Lonchocarpus spp. Important medicines from roots are ginseng
Ginseng
Ginseng is any one of eleven species of slow-growing perennial plants with fleshy roots, belonging to the genus Panax of the family Araliaceae....

, aconite
Aconitum
Aconitum , known as aconite, monkshood, wolfsbane, leopard's bane, women's bane, Devil's helmet or blue rocket, is a genus of over 250 species of flowering plants belonging to the buttercup family .-Overview:These herbaceous perennial plants are chiefly natives of the mountainous parts of the...

, ipecac
Syrup of ipecac
Syrup of ipecac , commonly referred to as ipecac, is derived from the dried rhizome and roots of the ipecacuanha plant, and is a well known emetic .-Preparation:...

, gentian
Gentian
Gentiana is a genus of flowering plants belonging to the Gentian family , tribe Gentianeae and monophyletic subtribe Gentianinae. With about 400 species, it is considered a large genus.-Habitat:...

 and reserpine
Reserpine
Reserpine is an indole alkaloid antipsychotic and antihypertensive drug that has been used for the control of high blood pressure and for the relief of psychotic symptoms, although because of the development of better drugs for these purposes and because of its numerous side-effects, it is rarely...

. Several legumes that have nitrogen-fixing root nodules are used as green manure crops, which provide nitrogen fertilizer for other crops when plowed under. Specialized bald cypress roots, termed knees, are sold as souvenirs, lamp bases and carved into folk art. Native Americans used the flexible roots of white spruce
White Spruce
Picea glauca is a species of spruce native to boreal forests in the north of North America, from central Alaska east to Newfoundland, and south to northern Montana, Minnesota, Wisconsin, Michigan, upstate New York, Vermont, New Hampshire, and Maine; there is also an isolated population in the...

 for basketry.

Tree
Tree
A tree is a perennial woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or trunk with clear apical dominance. A minimum height specification at maturity is cited by some authors, varying from 3 m to...

 roots can heave and destroy concrete sidewalks and crush or clog buried pipes. The aerial roots of strangler fig
Strangler Fig
Strangler fig is the common name for a number of tropical and subtropical plant species, including some banyans and unrelated vines, including among many other species:* Ficus aurea, also known as the Florida Strangler Fig...

 have damaged ancient Mayan
Maya architecture
A unique and spectacular style, Maya architecture spans several thousands of years. Often the most dramatic and easily recognizable as Maya are the stepped pyramids from the Terminal Pre-classic period and beyond. Being based on the general Mesoamerican architectural traditions these pyramids...

 temple
Temple
A temple is a structure reserved for religious or spiritual activities, such as prayer and sacrifice, or analogous rites. A templum constituted a sacred precinct as defined by a priest, or augur. It has the same root as the word "template," a plan in preparation of the building that was marked out...

s in Central America
Central America
Central America is the central geographic region of the Americas. It is the southernmost, isthmian portion of the North American continent, which connects with South America on the southeast. When considered part of the unified continental model, it is considered a subcontinent...

 and the temple of Angkor Wat
Angkor Wat
Angkor Wat is a temple complex at Angkor, Cambodia, built for the king Suryavarman II in the early 12th century as his state temple and capital city. As the best-preserved temple at the site, it is the only one to have remained a significant religious centre since its foundation – first Hindu,...

 in Cambodia
Cambodia
Cambodia , officially known as the Kingdom of Cambodia, is a country located in the southern portion of the Indochina Peninsula in Southeast Asia...

.

Vegetative propagation of plants via cuttings depends on adventitious root formation. Hundreds of millions of plants are propagated via cuttings annually including chrysanthemum
Chrysanthemum
Chrysanthemums, often called mums or chrysanths, are of the genus constituting approximately 30 species of perennial flowering plants in the family Asteraceae which is native to Asia and northeastern Europe.-Etymology:...

, poinsettia
Poinsettia
Euphorbia pulcherrima, commonly known as Zack Wood or noche buena, is a species of flowering plant indigenous to Mexico and Central America. The name "poinsettia" is after Joel Roberts Poinsett, the first United States Minister to Mexico, who introduced the plant into the US in 1825...

, carnation
Carnation
Dianthus caryophyllus is a species of Dianthus. It is probably native to the Mediterranean region but its exact range is unknown due to extensive cultivation for the last 2,000 years. It is the wild ancestor of the garden carnation.It is a herbaceous perennial plant growing to 80 cm tall...

, ornamental shrub
Shrub
A shrub or bush is distinguished from a tree by its multiple stems and shorter height, usually under 5–6 m tall. A large number of plants may become either shrubs or trees, depending on the growing conditions they experience...

s and many houseplants.

Roots can also protect the environment by holding the soil to prevent soil erosion. This is especially important in areas such as sand dunes.

See also

  • Rooting Powder
    Auxin
    Auxins are a class of plant hormones with some morphogen-like characteristics. Auxins have a cardinal role in coordination of many growth and behavioral processes in the plant's life cycle and are essential for plant body development. Auxins and their role in plant growth were first described by...

  • Fibrous root system
    Fibrous root system
    A fibrous root system is the opposite of a taproot system. It is usually formed by thin, moderately branching roots growing from the stem...

  • Mycorrhiza
    Mycorrhiza
    A mycorrhiza is a symbiotic association between a fungus and the roots of a vascular plant....

     - root symbiosis in which individual hyphae extending from the mycelium of a fungus colonize the roots of a host plant.
  • Rhizosphere
    Rhizosphere
    The rhizosphere is the narrow region of soil that is directly influenced by root secretions and associated soil microorganisms. Soil which is not part of the rhizosphere is known as bulk soil. The rhizosphere contains many bacteria that feed on sloughed-off plant cells, termed rhizodeposition, and...

     - region of soil around the root influenced by root secretions and microorganisms present
  • Root cutting
  • Stolon
    Stolon
    In biology, stolons are horizontal connections between organisms. They may be part of the organism, or of its skeleton; typically, animal stolons are external skeletons.-In botany:...

  • Taproot
    Taproot
    A taproot is an enlarged, somewhat straight to tapering plant root that grows vertically downward. It forms a center from which other roots sprout laterally.Plants with taproots are difficult to transplant...

  • Drought rhizogenesis
    Drought Rhizogenesis
    Drought rhizogenesis is an adaptive root response to drought stress. New emerging roots are short, swollen, and hairless, capable of retaining turgor pressure and resistant to prolonged desiccation. Upon rewatering, they are capable of quickly forming an absorbing root surface and hair growth...

  • Cypress knee
    Cypress knee
    In the biology of trees, a cypress knee is a distinctive structure in a root of a cypress tree of any of various species of the subfamily Taxodioideae. Their function is unknown, but they are generally seen in swamps...


External links