root

root¹

—rootlike, adj.

/rooht, root/, n.

1. a part of the body of a plant that develops, typically, from the radicle and grows downward into the soil, anchoring the plant and absorbing nutriment and moisture.

2. a similar organ developed from some other part of a plant, as one of those by which ivy clings to its support.

3. any underground part of a plant, as a rhizome.

4. something resembling or suggesting the root of a plant in position or function: roots of wires and cables.

5. the embedded or basal portion of a hair, tooth, nail, nerve, etc.

6. the fundamental or essential part: the root of a matter.

7. the source or origin of a thing: The love of money is the root of all evil.

8. a person or family as the source of offspring or descendants.

9. an offshoot or scion.

10. Math.

a. a quantity that, when multiplied by itself a certain number of times, produces a given quantity: The number 2 is the square root of 4, the cube root of 8, and the fourth root of 16.

b. r th root, the quantity raised to the power 1/r: The number 2 is the ¹/₃ root of 8.

c. a value of the argument of a function for which the function takes the value zero.

11. Gram.

a. a morpheme that underlies an inflectional or derivational paradigm, as dance, the root in danced, dancer, or ten-, the root of Latin tendere "to stretch."

b. such a form reconstructed for a parent language, as *sed-, the hypothetical proto-Indo-European root meaning "sit."

12. roots,

a. a person's original or true home, environment, and culture: He's lived in New York for twenty years, but his roots are in France.

b. the personal relationships, affinity for a locale, habits, and the like, that make a country, region, city, or town one's true home: He lived in Tulsa for a few years, but never established any roots there.

c. personal identification with a culture, religion, etc., seen as promoting the development of the character or the stability of society as a whole.

13. Music.

a. the fundamental tone of a compound tone or of a series of harmonies.

b. the lowest tone of a chord when arranged as a series of thirds; the fundamental.

14. Mach.

a. (in a screw or other threaded object) the narrow inner surface between threads. Cf. crest (def. 18), flank (def. 7).

b. (in a gear) the narrow inner surface between teeth.

15. Australian Informal. an act of sexual intercourse.

16. Shipbuilding. the inner angle of an angle iron.

17. root and branch, utterly; entirely: to destroy something root and branch.

18. take root,

a. to send out roots; begin to grow.

b. to become fixed or established: The prejudices of parents usually take root in their children.

v.i.

19. to become fixed or established.

v.t.

20. to fix by or as if by roots: We were rooted to the spot by surprise.

21. to implant or establish deeply: Good manners were rooted in him like a second nature.

22. to pull, tear, or dig up by the roots (often fol. by up or out).

23. to extirpate; exterminate; remove completely (often fol. by up or out): to root out crime.

[bef. 1150; (n.) ME; late OE rot < ON rot; akin to OE wyrt plant, WORT², G Wurzel, L radix (see RADIX), Gk rhíza (see RHIZOME); (v.) ME roten, rooten, deriv. of the n.]

Syn. 6. basis. 7. beginning, derivation, rise, fountainhead. 8. parent. 23. eradicate.

root²

/rooht, root/, v.i.

1. to turn up the soil with the snout, as swine.

2. to poke, pry, or search, as if to find something: to root around in a drawer for loose coins.

v.t.

3. to turn over with the snout (often fol. by up).

4. to unearth; bring to light (often fol. by up).

[1530-40; var. of obs. wroot (OE wrotan, akin to wrot a snout)]

root³

/rooht/ or, sometimes, /root/, v.i.

1. to encourage a team or contestant by cheering or applauding enthusiastically.

2. to lend moral support: The whole group will be rooting for him.

[1885-90, Amer.; perh. var. of ROUT⁴]

Syn. 1. cheer, applaud, boost, support.

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In botany, the underground anchoring part of a plant.

It grows downward in response to gravity, absorbs water and dissolved minerals, and stores reserve food. Primary root systems have a deep sturdy taproot (in gymnosperms and dicots; see cotyledon) plus secondary or lateral smaller roots, and root hairs. Grasses and other monocots produce a shallow diffuse mass of fibrous secondary roots. Additional support (e.g., in corn and orchids) comes from stem offshoots called adventitious, or prop, roots. Fleshy roots that store food may be modified taproots (e.g., carrots, turnips, and beets) or modified adventitious roots (e.g. cassava). Tubers such as the potato are modified, fleshy, underground stems, or rhizomes. Aerial roots arise from the stem and either pass for some distance through the air before reaching the soil or remain hanging in the air.

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▪ mathematics

      in mathematics, a solution to an equation, usually expressed as a number or an algebraic formula.

      In the 9th century, Arab writers usually called one of the equal factors of a number jadhr (“root”), and their medieval European translators used the Latin word radix (from which derives the adjective radical). If a is a positive real number and n a positive integer, there exists a unique positive real number x such that xⁿ = a. This number—the (principal) nth root of a—is written ⁿ√ a or a^1/n. The integer n is called the index of the root. For n = 2, the root is called the square root and is written √ a . The root ³√ a is called the cube root of a. If a is negative and n is odd, the unique negative nth root of a is termed principal. For example, the principal cube root of –27 is –3.

      If a whole number (positive integer) has a rational nth root—i.e., one that can be written as a common fraction—then this root must be an integer. Thus, 5 has no rational square root because 2² is less than 5 and 3² is greater than 5. Exactly n complex numbers satisfy the equation xⁿ = 1, and they are called the complex nth roots of unity. If a regular polygon of n sides is inscribed in a unit circle centred at the origin so that one vertex lies on the positive half of the x-axis, the radii to the vertices are the vectors representing the n complex nth roots of unity. If the root whose vector makes the smallest positive angle with the positive direction of the x-axis is denoted by the Greek letter omega, ω, then ω, ω², ω³, …, ω_n = 1 constitute all the nth roots of unity. For example, ω = −¹/₂ + ^{√( −3 )} /₂, ω² = −¹/₂ − ^{√( −3 )} /₂, and ω³ = 1 are all the cube roots of unity. Any root, symbolized by the Greek letter epsilon, ε, that has the property that ε, ε², …, εⁿ = 1 give all the nth roots of unity is called primitive. Evidently the problem of finding the nth roots of unity is equivalent to the problem of inscribing a regular polygon of n sides in a circle. For every integer n, the nth roots of unity can be determined in terms of the rational numbers by means of rational operations and radicals; but they can be constructed by ruler and compasses (i.e., determined in terms of the ordinary operations of arithmetic and square roots) only if n is a product of distinct prime numbers of the form 2^h + 1, or 2^k times such a product, or is of the form 2^k. If a is a complex number not 0, the equation xⁿ = a has exactly n roots, and all the nth roots of a are the products of any one of these roots by the nth roots of unity.

      The term root has been carried over from the equation xⁿ = a to all polynomial equations. Thus, a solution of the equation f(x) = a₀xⁿ + a₁x^n − 1 + … + a_n − 1x + a_n = 0, with a₀ ≠ 0, is called a root of the equation. If the coefficients lie in the complex field, an equation of the nth degree has exactly n (not necessarily distinct) complex roots. If the coefficients are real and n is odd, there is a real root. But an equation does not always have a root in its coefficient field. Thus, x² − 5 = 0 has no rational root, although its coefficients (1 and –5) are rational numbers.

      More generally, the term root may be applied to any number that satisfies any given equation, whether a polynomial equation or not. Thus π is a root of the equation x sin (x) = 0.

▪ plant

 in botany, that part of a plant normally underground. Its primary functions are anchorage of the plant, absorption of water and dissolved minerals and conduction of these to the stem, and storage of reserve foods.

      Many plants develop subterranean structures that are in reality specialized stems (e.g., corms, tubers). The root differs from these mainly by lacking leaf scars and buds, having a root cap, and having branches that originate from internal tissue rather than from buds.

      The primary root, or radicle, is the first organ to appear when a seed germinates. It grows downward into the soil, anchoring the seedling. In gymnosperms and dicotyledons, the radicle becomes a taproot. It grows downward, and branch, or secondary, roots grow laterally from it. This type of system is called a taproot system. In some plants, such as carrots and turnips, the taproot serves as a storage organ and becomes swollen with foodstuffs.

      Grasses and other monocotyledons have a fibrous root system, characterized by a mass of roots of about equal diameter. This network of roots does not arise as branches of the primary root but consists of many branching roots that emerge from the base of the stem.

      Roots grow in length only from their ends. The very tip of the root is covered by a protective, thimble-shaped root cap. Just behind the root cap lies the apical meristem, a tissue of actively dividing cells. Some of the cells produced by the apical meristem are added to the root cap, but most of them are added to the region of elongation, which lies just above the meristematic region. It is in the region of elongation that growth in length occurs. Above this elongation zone lies the region of maturation, where the primary tissues of the root mature, completing the process of cell differentiation that actually begins in the upper portion of the meristematic region.

      The primary tissues of the root are, from outermost to innermost, the epidermis, the cortex, and the vascular cylinder. The epidermis is composed of thin-walled cells and is usually only one cell layer thick. The absorption of water and dissolved minerals occurs through the epidermis, a process greatly enhanced in most land plants by the presence of root hairs—slender, tubular extensions of the epidermal cell wall that are found only in the region of maturation. The absorption of water is chiefly via osmosis, which occurs because (1) water is present in higher concentrations in the soil than within the epidermal cells (where it contains salts, sugars, and other dissolved organic products) and (2) the membrane of the epidermal cells is permeable to water but not to many of the substances dissolved in the internal fluid. These conditions create an osmotic gradient, whereby water flows into the epidermal cells. This flow exerts a force, called root pressure, that helps drive the water through the roots. Root pressure is partially responsible for the rise of water in plants, but it cannot alone account for the transport of water to the top of tall trees.

      The cortex conducts water and dissolved minerals across the root from the epidermis to the vascular cylinder, whence it is transported to the rest of the plant. The cortex also stores food transported downward from the leaves through the vascular tissues. The innermost layer of the cortex usually consists of a tightly packed layer of cells, called the endodermis, which regulates the flow of materials between the cortex and the vascular tissues.

      The vascular cylinder is interior to the endodermis and is surrounded by the pericycle, a layer of cells that gives rise to branch roots. The conductive tissues of the vascular cylinder are usually arranged in a star-shaped pattern. The xylem tissue, which carries water and dissolved minerals, comprises the core of the star; the phloem tissue, which carries food, is located in small groups between the points of the star.

      The older roots of woody plants form secondary tissues, which lead to an increase in girth. These secondary tissues are produced by the vascular cambium and the cork cambium. The former arises from meristematic cells that lie between the primary xylem and phloem. As it develops, the vascular cambium forms a ring around the primary vascular cylinder. Cell divisions in the vascular cambium produce secondary xylem (wood) to the inside of the ring and secondary phloem to the outside. The growth of these secondary vascular tissues pushes the pericycle outward and splits the cortex and epidermis. The pericycle becomes the cork cambium, producing cork cells (outer bark) that replace the cortex and epidermis.

      Some roots, called adventitious roots, arise from an organ other than the root—usually a stem, sometimes a leaf. They are especially numerous on underground stems. The formation of adventitious roots makes it possible to vegetatively propagate many plants from stem or leaf cuttings.

      Roots are not always underground. When they arise from the stem and either pass for some distance through the air before reaching the soil or remain hanging in the air, they are called aerial. They are seen well in corn (maize), screw pine, and banyan, where they eventually assist in supporting the plant.

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