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Latex is an emulsion (stable dispersion) of polymer microparticles in water. Latexes are found in
nature Nature, in the broadest sense, is the physical world or universe. "Nature" can refer to the phenomena of the physical world, and also to life in general. The study of nature is a large, if not the only, part of science. Although humans are p ...
, but synthetic latexes are common as well. In nature, latex is found as a milky fluid found in 10% of all flowering plants (angiosperms). It is a complex emulsion that coagulates on exposure to air, consisting of proteins,
alkaloid Alkaloids are a class of basic, naturally occurring organic compounds that contain at least one nitrogen atom. This group also includes some related compounds with neutral and even weakly acidic properties. Some synthetic compounds of similar s ...
s, starches, sugars,
oil An oil is any nonpolar chemical substance that is composed primarily of hydrocarbons and is hydrophobic (does not mix with water) & lipophilic (mixes with other oils). Oils are usually flammable and surface active. Most oils are unsaturated ...
s,
tannin Tannins (or tannoids) are a class of astringent, polyphenolic biomolecules that bind to and precipitate proteins and various other organic compounds including amino acids and alkaloids. The term ''tannin'' (from Anglo-Norman ''tanner'', ...
s, resins, and gums. It is usually exuded after tissue injury. In most plants, latex is white, but some have yellow, orange, or scarlet latex. Since the 17th century, latex has been used as a term for the fluid substance in plants, deriving from the Latin word for "liquid". It serves mainly as
defense Defense or defence may refer to: Tactical, martial, and political acts or groups * Defense (military), forces primarily intended for warfare * Civil defense, the organizing of civilians to deal with emergencies or enemy attacks * Defense indust ...
against herbivorous insects. Latex is not to be confused with plant sap; it is a distinct substance, separately produced, and with different functions. The word latex is also used to refer to natural latex rubber, particularly non-
vulcanized Vulcanization (British: Vulcanisation) is a range of processes for hardening rubbers. The term originally referred exclusively to the treatment of natural rubber with sulfur, which remains the most common practice. It has also grown to include ...
rubber. Such is the case in products like latex
glove A glove is a garment covering the hand. Gloves usually have separate sheaths or openings for each finger and the thumb. If there is an opening but no (or a short) covering sheath for each finger they are called fingerless gloves. Fingerless glo ...
s, latex condoms and latex clothing.


Biology


Articulated laticifers

The
cells Cell most often refers to: * Cell (biology), the functional basic unit of life Cell may also refer to: Locations * Monastic cell, a small room, hut, or cave in which a religious recluse lives, alternatively the small precursor of a monastery w ...
( laticifers) in which latex is found make up the laticiferous system, which can form in two very different ways. In many plants, the laticiferous system is formed from rows of cells laid down in the meristem of the stem or root. The
cell wall A cell wall is a structural layer surrounding some types of cells, just outside the cell membrane. It can be tough, flexible, and sometimes rigid. It provides the cell with both structural support and protection, and also acts as a filtering me ...
s between these cells are dissolved so that continuous tubes, called latex vessels, are formed. Since these vessels are made of many cells, they are known as ''articulated laticifers''. This method of formation is found in the poppy family and in the rubber trees ( Para rubber tree, members of the family Euphorbiaceae, members of the mulberry and fig family, such as the Panama rubber tree ''
Castilla elastica ''Castilla elastica'', the Panama rubber tree, is a tree native to the tropical areas of Mexico, Central America, and northern South America. It was the principal source of latex among the Mesoamerican peoples in pre-Columbian times. The latex ...
''), and members of the family
Asteraceae The family Asteraceae, alternatively Compositae, consists of over 32,000 known species of flowering plants in over 1,900 genera within the order Asterales. Commonly referred to as the aster, daisy, composite, or sunflower family, Compositae w ...
. For instance, ''
Parthenium argentatum ''Parthenium argentatum'', commonly known as the guayule ( or , as in Spanish), is a perennial woody shrub in the family Asteraceae that is native to the rangeland area of the Chihuahuan Desert; including the southwestern United States and north ...
'' the guayule plant, is in the tribe Heliantheae; other latex-bearing Asteraceae with articulated laticifers include members of the
Cichorieae The Cichorieae (also called Lactuceae) are a tribe in the plant family Asteraceae that includes 93 genera, more than 1,600 sexually reproductive species and more than 7,000 apomictic species. They are found primarily in temperate regions of the E ...
, a clade whose members produce latex, some of them in commercially interesting amounts. This includes ''
Taraxacum kok-saghyz ''Taraxacum kok-saghyz'', often abbreviated as ''TKS'' and commonly referred to as the Kazakh dandelion, rubber root, or Russian dandelion, is a species of dandelion native to Kazakhstan, Kyrgyzstan and Uzbekistan, that is notable for its product ...
'', a species cultivated for latex production.


Non-articulated laticifers

In the
milkweed ''Asclepias'' is a genus of herbaceous, perennial, flowering plants known as milkweeds, named for their latex, a milky substance containing cardiac glycosides termed cardenolides, exuded where cells are damaged. Most species are toxic to hum ...
and
spurge ''Euphorbia'' is a very large and diverse genus of flowering plants, commonly called spurge, in the family Euphorbiaceae. "Euphorbia" is sometimes used in ordinary English to collectively refer to all members of Euphorbiaceae (in deference to t ...
families, on the other hand, the laticiferous system is formed quite differently. Early in the development of the seedling, latex cells differentiate, and as the plant grows these latex cells grow into a branching system extending throughout the plant. In many euphorbs, the entire structure is made from a single cell – this type of system is known as a ''non-articulated laticifer'', to distinguish it from the multi-cellular structures discussed above. In the mature plant, the entire laticiferous system is descended from a single cell or group of cells present in the embryo. The laticiferous system is present in all parts of the mature plant, including roots, stems,
leaves A leaf ( : leaves) is any of the principal appendages of a vascular plant stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, ste ...
, and sometimes the fruits. It is particularly noticeable in the cortical tissues. Latex is usually exuded as a white liquid, but is some cases it can be clear, yellow or red, as in
Cannabaceae Cannabaceae is a small family of flowering plants, known as the hemp family. As now circumscribed, the family includes about 170 species grouped in about 11 genera, including ''Cannabis'' (hemp), ''Humulus'' (hops) and ''Celtis'' (hackberries). ...
.


Productive species

Latex is produced by 20,000 flowering plant species from over 40 families. These include both dicots and
monocots Monocotyledons (), commonly referred to as monocots, ( Lilianae ''sensu'' Chase & Reveal) are grass and grass-like flowering plants (angiosperms), the seeds of which typically contain only one embryonic leaf, or cotyledon. They constitute one of ...
. Latex has been found in 14 percent of tropical plant species, as well as six percent of temperate plant species. Several members of the fungal kingdom also produce latex upon injury, such as '' Lactarius deliciosus'' and other milk-caps. This suggests it is the product of convergent evolution and has been selected for on many separate occasions.


Defense function

Latex functions to protect the plant from herbivores. The idea was first proposed in 1887 by Joseph F. James, who noted that latex
carries with it at the same time such disagreeable properties that it becomes a better protection to the plant from enemies than all the thorns, prickles, or hairs that could be provided. In this plant, so copious and so distasteful has the sap become that it serves a most important purpose in its economy.
Evidence showing this defense function include the finding that
slug Slug, or land slug, is a common name for any apparently shell-less terrestrial gastropod mollusc. The word ''slug'' is also often used as part of the common name of any gastropod mollusc that has no shell, a very reduced shell, or only a smal ...
s will eat leaves drained of their latex but not intact ones, that many insects sever the veins carrying latex before they feed, and that the latex of '' Asclepias humistrata'' (sandhill
milkweed ''Asclepias'' is a genus of herbaceous, perennial, flowering plants known as milkweeds, named for their latex, a milky substance containing cardiac glycosides termed cardenolides, exuded where cells are damaged. Most species are toxic to hum ...
) kills by trapping 30% of newly hatched
monarch butterfly The monarch butterfly or simply monarch (''Danaus plexippus'') is a milkweed butterfly (subfamily Danainae) in the family Nymphalidae. Other common names, depending on region, include milkweed, common tiger, wanderer, and black-veined brown. ...
caterpillars. Other evidence is that latex contains 50–1000× higher concentrations of defense substances than other plant tissues. These toxins include ones that are also toxic to the plant and consist of a diverse range of chemicals that are either poisonous or " antinutritive." Latex is actively moved to the area of injury; in the case of '' Cryptostegia grandiflora'', latex more than 70 cm from the site of injury is mobilized. The large hydrostatic pressure in this vine enables an extremely high flow rate of latex. In a 1935 report the botanist Catherine M. Bangham observed that "piercing the fruit stalk of ''Cryptostegia grandiflora'' produced a jet of latex over a meter long, and maintained his jetfor several seconds." The clotting property of latex is functional in this defense since it limits wastage and its stickiness traps insects and their mouthparts. While there exist other explanations for the existence of latex including storage and movement of plant nutrients, waste, and maintenance of water balance that " sentially none of these functions remain credible and none have any empirical support".


Applications

The latex of many species can be processed to produce many materials. *
Balatá ''Manilkara bidentata'' is a species of ''Manilkara'' native to a large area of northern South America, Central America and the Caribbean. Common names include bulletwood, balatá, ausubo, massaranduba, quinilla, and (ambiguously) " cow-tree". D ...
and
gutta percha Gutta-percha is a tree of the genus ''Palaquium'' in the family Sapotaceae. The name also refers to the rigid, naturally biologically inert, resilient, electrically nonconductive, thermoplastic latex derived from the tree, particularly from ' ...
latex contain an inelastic polymer related to rubber. *
Chicle Chicle () is a natural gum traditionally used in making chewing gum and other products. It is collected from several species of Mesoamerican trees in the genus ''Manilkara'', including '' M. zapota'', '' M. chicle'', '' M. staminodella'', and '' ...
and jelutong tree latex was used in
chewing gum Chewing gum is a soft, cohesive substance designed to be chewed without being swallowed. Modern chewing gum is composed of gum base, sweeteners, softeners/ plasticizers, flavors, colors, and, typically, a hard or powdered polyol coating. Its ...
.


Personal and healthcare products

Natural rubber Rubber, also called India rubber, latex, Amazonian rubber, ''caucho'', or ''caoutchouc'', as initially produced, consists of polymers of the organic compound isoprene, with minor impurities of other organic compounds. Thailand, Malaysia, and ...
is the most important product obtained from latex; more than 12,000 plant species yield latex containing rubber, though in the vast majority of those species the rubber is not suitable for commercial use. This latex is used to make many other products including
mattress A mattress is a large, usually rectangular pad for supporting a lying person. It is designed to be used as a bed, or on a bed frame as part of a bed. Mattresses may consist of a quilted or similarly fastened case, usually of heavy cloth, cont ...
es,
glove A glove is a garment covering the hand. Gloves usually have separate sheaths or openings for each finger and the thumb. If there is an opening but no (or a short) covering sheath for each finger they are called fingerless gloves. Fingerless glo ...
s,
swim cap A swimming cap, swim cap or bathing cap, is a tightly fitted, skin-tight garment, commonly made from silicone, latex or lycra, worn on the head by recreational and competitive swimmers. Swim caps are worn for various reasons: they can be worn to ...
s, condoms,
catheter In medicine, a catheter (/ˈkæθətər/) is a thin tube made from medical grade materials serving a broad range of functions. Catheters are medical devices that can be inserted in the body to treat diseases or perform a surgical procedure. Cath ...
s and
balloon A balloon is a flexible bag that can be inflated with a gas, such as helium, hydrogen, nitrous oxide, oxygen, and air. For special tasks, balloons can be filled with smoke, liquid water, granular media (e.g. sand, flour or rice), or light s ...
s.


Opium and opiates

Dried latex from the opium poppy is called opium, the source of several useful
analgesic An analgesic drug, also called simply an analgesic (American English), analgaesic (British English), pain reliever, or painkiller, is any member of the group of drugs used to achieve relief from pain (that is, analgesia or pain management). It i ...
alkaloid Alkaloids are a class of basic, naturally occurring organic compounds that contain at least one nitrogen atom. This group also includes some related compounds with neutral and even weakly acidic properties. Some synthetic compounds of similar s ...
s such as
codeine Codeine is an opiate and prodrug of morphine mainly used to treat pain, coughing, and diarrhea. It is also commonly used as a recreational drug. It is found naturally in the sap of the opium poppy, ''Papaver somniferum''. It is typically used ...
,
thebaine Thebaine (paramorphine), also known as codeine methyl enol ether, is an opiate alkaloid, its name coming from the Greek Θῆβαι, '' Thēbai'' (Thebes), an ancient city in Upper Egypt. A minor constituent of opium, thebaine is chemically similar ...
, and
morphine Morphine is a strong opiate that is found naturally in opium, a dark brown resin in poppies (''Papaver somniferum''). It is mainly used as a pain medication, and is also commonly used recreationally, or to make other illicit opioids. There ...
, the latter two of which can then further be used in the synthesis and manufacture of other (typically stronger)
opioids Opioids are substances that act on opioid receptors to produce morphine-like effects. Medically they are primarily used for pain relief, including anesthesia. Other medical uses include suppression of diarrhea, replacement therapy for opioid use ...
for medicinal use, and of
heroin Heroin, also known as diacetylmorphine and diamorphine among other names, is a potent opioid mainly used as a recreational drug for its euphoric effects. Medical grade diamorphine is used as a pure hydrochloride salt. Various white and brown ...
for the illegal drug trade. The opium poppy is also the source of medically useful non-analgesic alkaloids, such as
papaverine Papaverine (Latin ''papaver'', "poppy") is an opium alkaloid antispasmodic drug, used primarily in the treatment of visceral spasms and vasospasms (especially those involving the intestines, heart, or brain), occasionally in the treatment of erec ...
and
noscapine Noscapine (also known as Narcotine, Nectodon, Nospen, Anarcotine and (archaic) Opiane) is a benzylisoquinoline alkaloid, of the phthalideisoquinoline structural subgroup, which has been isolated from numerous species of the family Papaveraceae ...
.


Clothing

Latex is used in many types of clothing. Worn on the body (or applied directly by painting), it tends to be skin-tight, producing a "second skin" effect.


Industrial and biological applications from synthetic latexes

Synthetic latexes are used in
coating A coating is a covering that is applied to the surface of an object, usually referred to as the substrate. The purpose of applying the coating may be decorative, functional, or both. Coatings may be applied as liquids, gases or solids e.g. Powde ...
s (e.g., latex paint) and
glue Adhesive, also known as glue, cement, mucilage, or paste, is any non-metallic substance applied to one or both surfaces of two separate items that binds them together and resists their separation. The use of adhesives offers certain advant ...
s because they solidify by coalescence of the polymer particles as the water evaporates. These synthetic latexes therefore can form films without releasing potentially toxic organic solvents in the environment. Other uses include cement additives and to conceal information on
scratchcard A scratchcard (also called a scratch off, scratch ticket, scratcher, scratchum, scratch-it, scratch game, scratch-and-win, instant game, instant lottery, scratchie, lot scrots, or scritchies) is a card designed for competitions, often made of ...
s. Latex, usually
styrene Styrene () is an organic compound with the chemical formula C6H5CH=CH2. This derivative of benzene is a colorless oily liquid, although aged samples can appear yellowish. The compound evaporates easily and has a sweet smell, although high concen ...
-based, is also used in immunoassays.


Allergic reactions

Some people only experience a mild allergy when exposed to latex, like
eczema Dermatitis is inflammation of the skin, typically characterized by itchiness, redness and a rash. In cases of short duration, there may be small blisters, while in long-term cases the skin may become thickened. The area of skin involved can ...
,
contact dermatitis Contact dermatitis is a type of acute or chronic inflammation of the skin caused by exposure to chemical or physical agents. Symptoms of contact dermatitis can include itchy or dry skin, a red rash, bumps, blisters, or swelling. These rashes are ...
or developing a rash. Others have a serious
latex allergy Latex allergy is a medical term encompassing a range of allergic reactions to the proteins present in natural rubber latex. It generally develops after repeated exposure to products containing natural rubber latex. When latex-containing medical d ...
, and exposure to latex products such as latex gloves can cause
anaphylactic shock Anaphylaxis is a serious, potentially fatal allergic reaction and medical emergency that is rapid in onset and requires immediate medical attention regardless of use of emergency medication on site. It typically causes more than one of the follow ...
. Guayule latex has only 2% of the levels of protein found in '' Hevea'' latexes, and is being researched as a lower-allergen substitute. Additionally, chemical processes may be employed to reduce the amount of antigenic protein in ''Hevea'' latex, yielding alternative materials such as Vytex Natural Rubber Latex which provide significantly reduced exposure to latex allergens. About half of people with spina bifida are also allergic to natural latex rubber, as well as people who have had multiple surgeries, and people who have had prolonged exposure to natural latex.


Microbial degradation

Several species of the
microbe A microorganism, or microbe,, ''mikros'', "small") and ''organism'' from the el, ὀργανισμός, ''organismós'', "organism"). It is usually written as a single word but is sometimes hyphenated (''micro-organism''), especially in olde ...
genera ''
Actinomycetes The Actinomycetales is an order of Actinomycetota. A member of the order is often called an actinomycete. Actinomycetales are generally gram-positive and anaerobic and have mycelia in a filamentous and branching growth pattern. Some actinomycete ...
'', '' Streptomyces'', ''
Nocardia ''Nocardia'' is a genus of weakly staining Gram-positive, catalase-positive, rod-shaped bacteria. It forms partially acid-fast beaded branching filaments (acting as fungi, but being truly bacteria). It contains a total of 85 species. Some spe ...
'', '' Micromonospora'', and ''
Actinoplanes ''Actinoplanes'' is a genus in the family Micromonosporaceae. They have aerial mycelia and spherical, motile spores. ''Actinoplanes'' species produce the pharmaceutically important compounds valienamine (a precursor to the antidiabetic drug aca ...
'' are capable of consuming rubber latex. However, the rate of biodegradation is slow, and the growth of bacteria utilizing rubber as a sole carbon source is also slow.


See also

* Latex clothing *
Natural rubber Rubber, also called India rubber, latex, Amazonian rubber, ''caucho'', or ''caoutchouc'', as initially produced, consists of polymers of the organic compound isoprene, with minor impurities of other organic compounds. Thailand, Malaysia, and ...
*


References


Footnotes


Notes


External links

* {{Authority control Materials Sculpture materials Rubber