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A taproot is a large, central, and dominant
root In vascular plants, the roots are the organs of a plant that are modified to provide anchorage for the plant and take in water and nutrients into the plant body, which allows plants to grow taller and faster. They are most often below the sur ...
from which other roots sprout laterally. Typically a taproot is somewhat straight and very thick, is tapering in shape, and grows directly downward. In some plants, such as the carrot, the taproot is a storage organ so well developed that it has been cultivated as a vegetable. The taproot system contrasts with the adventitious or fibrous root system of plants with many branched roots, but many plants that grow a taproot during germination go on to develop branching root structures, although some that rely on the main root for storage may retain the dominant taproot for centuries, for example ''
Welwitschia ''Welwitschia'' is a monotypic gymnosperm genus, comprising solely the distinctive ''Welwitschia mirabilis'', endemic to the Namib desert within Namibia and Angola. ''Welwitschia'' is the only living genus of the family Welwitschiaceae and orde ...
''.Taproot also store nutrition. Plants with taproots are often vegetables.


Description

Dicot The dicotyledons, also known as dicots (or, more rarely, dicotyls), are one of the two groups into which all the flowering plants (angiosperms) were formerly divided. The name refers to one of the typical characteristics of the group: namely, t ...
s, one of the two divisions of
flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...
s (angiosperms), start with a taproot, which is one main root forming from the enlarging
radicle In botany, the radicle is the first part of a seedling (a growing plant embryo) 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 shoot emerges from the ...
of the seed. The tap root can be persistent throughout the life of the plant but is most often replaced later in the plant's development by a fibrous root system. A persistent taproot system forms when the radicle keeps growing and smaller lateral roots form along the taproot. The shape of taproots can vary but the typical shapes include: *Conical root: this type of root tuber is conical in shape, i.e. widest at the top and tapering steadily towards the bottom: e.g.
carrot The carrot ('' Daucus carota'' subsp. ''sativus'') is a root vegetable, typically orange in color, though purple, black, red, white, and yellow cultivars exist, all of which are domesticated forms of the wild carrot, ''Daucus carota'', nat ...
. *Fusiform root: this root is widest in the middle and tapers towards the top and the bottom: e.g.
radish The radish (''Raphanus raphanistrum'' subsp. ''sativus'') is an Eating, edible root vegetable of the family Brassicaceae that was domesticated in Asia prior to Roman Empire, Roman times. Radishes are grown and consumed throughout the world, be ...
. *Napiform root: the root has a
top A spinning top, or simply a top, is a toy with a squat body and a sharp point at the bottom, designed to be spun on its vertical axis, balancing on the tip due to the gyroscopic effect. Once set in motion, a top will usually wobble for a few ...
-like appearance. It is very broad at the top and tapers suddenly like a tail at the bottom: e.g.
turnip The turnip or white turnip (''Brassica rapa'' subsp. ''rapa'') is a root vegetable commonly grown in temperate climates worldwide for its white, fleshy taproot. The word ''turnip'' is a compound of ''turn'' as in turned/rounded on a lathe and ' ...
. Many taproots are modified into
storage organ A storage organ is a part of a plant specifically modified for storage of energy (generally in the form of carbohydrates) or water. Storage organs often grow underground, where they are better protected from attack by herbivores. Plants that have ...
s. Some plants with taproots: *
Beetroot The beetroot is the taproot portion of a beet plant, usually known in North America as beets while the vegetable is referred to as beetroot in British English, and also known as the table beet, garden beet, red beet, dinner beet or golden beet ...
*
Burdock ''Arctium'' is a genus of biennial plants commonly known as burdock, family Asteraceae. Native to Europe and Asia, several species have been widely introduced worldwide. Burdock's clinging properties, in addition to providing an excellent mecha ...
*
Carrot The carrot ('' Daucus carota'' subsp. ''sativus'') is a root vegetable, typically orange in color, though purple, black, red, white, and yellow cultivars exist, all of which are domesticated forms of the wild carrot, ''Daucus carota'', nat ...
*
Sugar beet A sugar beet is a plant whose root contains a high concentration of sucrose and which is grown commercially for sugar production. In plant breeding, it is known as the Altissima cultivar group of the common beet (''Beta vulgaris''). Together wi ...
*
Dandelion ''Taraxacum'' () is a large 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 is native to Eurasia and Nor ...
*
Parsley Parsley, or garden parsley (''Petroselinum crispum'') is a species of flowering plant in the family Apiaceae that is native to the central and eastern Mediterranean region (Sardinia, Lebanon, Israel, Cyprus, Turkey, southern Italy, Greece, Por ...
*
Parsnip The parsnip (''Pastinaca sativa'') is a root vegetable closely related to carrot and parsley, all belonging to the flowering plant family Apiaceae. It is a biennial plant usually grown as an annual. Its long taproot has cream-colored skin an ...
*
Poppy mallow ''Callirhoe'' is a genus of flowering plants in the Malva, mallow family, Malvaceae. Its nine species are commonly known as poppy mallows and all are native to the prairies and grasslands of North America. Of the nine species, some are Annual pla ...
*
Radish The radish (''Raphanus raphanistrum'' subsp. ''sativus'') is an Eating, edible root vegetable of the family Brassicaceae that was domesticated in Asia prior to Roman Empire, Roman times. Radishes are grown and consumed throughout the world, be ...
*
Sagebrush Sagebrush is the common name of several woody and herbaceous species of plants in the genus ''Artemisia''. The best known sagebrush is the shrub ''Artemisia tridentata''. Sagebrushes are native to the North American west. Following is an alph ...
*
Turnip The turnip or white turnip (''Brassica rapa'' subsp. ''rapa'') is a root vegetable commonly grown in temperate climates worldwide for its white, fleshy taproot. The word ''turnip'' is a compound of ''turn'' as in turned/rounded on a lathe and ' ...
* Common milkweed * trees such as
oak An oak is a tree or shrub in the genus ''Quercus'' (; Latin "oak tree") of the beech family, Fagaceae. There are approximately 500 extant species of oaks. The common name "oak" also appears in the names of species in related genera, notably ''L ...
s,
elm Elms are deciduous and semi-deciduous trees comprising the flowering plant genus ''Ulmus'' in the plant family Ulmaceae. They are distributed over most of the Northern Hemisphere, inhabiting the temperate and tropical-montane regions of North ...
s,
pine A pine is any conifer tree or shrub in the genus ''Pinus'' () of the family Pinaceae. ''Pinus'' is the sole genus in the subfamily Pinoideae. The World Flora Online created by the Royal Botanic Gardens, Kew and Missouri Botanical Garden accep ...
s and
fir Firs (''Abies'') are a genus of 48–56 species of evergreen coniferous trees in the family (biology), family Pinaceae. They are found on mountains throughout much of North America, North and Central America, Europe, Asia, and North Africa. The ...
s


Development of taproots

Taproots develop from the
radicle In botany, the radicle is the first part of a seedling (a growing plant embryo) 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 shoot emerges from the ...
of a seed, forming the primary root. It branches off to secondary roots, which in turn branch to form tertiary roots. These may further branch to form rootlets. For most plants species the radicle dies some time after seed germination, causing the development of a fibrous root system, which lacks a main downward-growing root. Most
tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are ...
s begin life with a taproot, but after one to a few years the main root system changes to a wide-spreading fibrous root system with mainly horizontal-growing surface roots and only a few vertical, deep-anchoring roots. A typical mature tree 30–50 m tall has a root system that extends horizontally in all directions as far as the tree is tall or more, but as much as 100% of the roots are in the top 50 cm of soil. Soil characteristics strongly influence the architecture of taproots; for example, deep and rich soils favour the development of vertical taproots in many oak species such as ''
Quercus kelloggii ''Quercus kelloggii'', the California black oak, also known as Kellogg oak, is an oak in the red oak section (genus ''Quercus'', section ''Lobatae'', series ''Agrifoliae''), native to western North America. Although genetically separated from the ...
'', while clay soils promote the growth of multiple taproots.


Horticultural considerations

Many plants with taproots are difficult to transplant, or even to grow in containers, because the root tends to grow deep rapidly and in many species comparatively slight obstacles or damage to the taproot will stunt or kill the plant. Among weeds with taproots
dandelion ''Taraxacum'' () is a large 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 is native to Eurasia and Nor ...
s are typical; being deep-rooted, they are hard to uproot and if the taproot breaks off near the top, the part that stays in the ground often resprouts such that, for effective control, the taproot needs to be severed at least several centimetres below ground level.


Gallery

file:Buckeye6.jpg, A tree taproot file:Plant taproots.jpg, A taproot


References


External links

*{{cite news , url=https://www.sciencedaily.com/releases/2006/01/060112035906.htm , date=2006-01-13 , work=Sciencedaily , title=Deep-rooted Plants Have Much Greater Impact On Climate Than Experts Thought , quote=The tap roots transfer
rain Rain is water droplets that have condensed from atmospheric water vapor and then fall under gravity. Rain is a major component of the water cycle and is responsible for depositing most of the fresh water on the Earth. It provides water f ...
water from the surface to reservoirs deep underground and redistribute water... increases
photosynthesis Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored i ...
and the evaporation of water... by 40 percent in the
dry season The dry season is a yearly period of low rainfall, especially in the tropics. The weather in the tropics is dominated by the tropical rain belt, which moves from the northern to the southern tropics and back over the course of the year. The te ...
... During the wet season, these plants can store as much as 10 percent of the annual
precipitation In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls under gravitational pull from clouds. The main forms of precipitation include drizzle, rain, sleet, snow, ice pellets, graupel and hail. ...
as deep as 13 meters (43 feet) underground, to be tapped during the dry months... tree roots acting like pipes to allow water to shift around much faster than it could otherwise
percolate Percolation (from Latin ''percolare'', "to filter" or "trickle through"), in physics, chemistry and materials science, refers to the movement and filtering of fluids through porous materials. It is described by Darcy's law. Broader application ...
through the
soil Soil, also commonly referred to as earth or dirt, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Some scientific definitions distinguish ''dirt'' from ''soil'' by restricting the former te ...
.
Fullerton Arboretum on taproots
Plant roots