Lignin

lignifiedlignificationligninslignifywoody15%decomposition-resistantdelignificationligneouslignifying
Lignin is a class of complex organic polymers that form key structural materials in the support tissues of vascular plants and some algae.wikipedia
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Vascular plant

vascular plantshigher plantsvascular
Lignin is a class of complex organic polymers that form key structural materials in the support tissues of vascular plants and some algae. Lignin is present in all vascular plants, but not in bryophytes, supporting the idea that the original function of lignin was restricted to water transport.
undefined 308,312 accepted known species ) that are defined as those land plants that have lignified tissues (the xylem) for conducting water and minerals throughout the plant.

Wood

heartwoodwoodensapwood
Lignins are particularly important in the formation of cell walls, especially in wood and bark, because they lend rigidity and do not rot easily.
It is an organic material - a natural composite of cellulose fibers that are strong in tension and embedded in a matrix of lignin that resists compression.

Ground tissue

sclerenchymaparenchymacollenchyma
Its most commonly noted function is the support through strengthening of wood (mainly composed of xylem cells and lignified sclerenchyma fibres) in vascular plants.
Their cell walls consist of cellulose, hemicellulose, and lignin.

Cellulose

cellulolyticcellulosiccellulose ester
It is one of the most abundant organic polymers on Earth, exceeded only by cellulose. Lignin fills the spaces in the cell wall between cellulose, hemicellulose, and pectin components, especially in vascular and support tissues: xylem tracheids, vessel elements and sclereid cells.
The high tensile strength of plant stems and of the tree wood also arises from the arrangement of cellulose fibers intimately distributed into the lignin matrix.

Biopolymer

biopolymersbio-polymerbiological polymers
As a biopolymer, lignin is unusual because of its heterogeneity and lack of a defined primary structure.
Other examples of biopolymers include rubber, suberin, melanin and lignin.

Carboniferous

Carboniferous PeriodCarbEarly Carboniferous
The Carboniferous Period (geology) is in part defined by the evolution of lignin.
The evolution of the wood fiber lignin and the bark-sealing, waxy substance suberin variously opposed decay organisms so effectively that dead materials accumulated long enough to fossilise on a large scale.

Bark (botany)

barktree barkperiderm
Lignins are particularly important in the formation of cell walls, especially in wood and bark, because they lend rigidity and do not rot easily.
Bark tissues make up by weight between 10–20% of woody vascular plants and consists of various biopolymers, tannins, lignin, suberin, suberan and polysaccharides.

Phenylpropanoid

phenylpropanoidsphenylpropanoid pathwayphenyl propanoid
These lignols are incorporated into lignin in the form of the phenylpropanoids p-hydroxyphenyl (H), guaiacyl (G), and syringyl (S), respectively.
From 4-coumaroyl-CoA emanates the biosynthesis of myriad natural products including lignols (precursors to lignin and lignocellulose), flavonoids, isoflavonoids, coumarins, aurones, stilbenes, catechin, and phenylpropanoids.

Monolignol

lignolslignol
Three monolignol monomers are precursors, all of which are methoxylated to various degrees: p-coumaryl alcohol, coniferyl alcohol, and sinapyl alcohol.
Monolignols are phytochemicals acting as source materials for biosynthesis of both lignans and lignin.

Polymer

polymershomopolymerpolymeric
Lignin is a class of complex organic polymers that form key structural materials in the support tissues of vascular plants and some algae. It is one of the most abundant organic polymers on Earth, exceeded only by cellulose.
There are other biopolymers such as rubber, suberin, melanin, and lignin.

Coniferyl alcohol

coniferol(C 10 H 12 O 3 ) ''n'' guaiacyl
Three monolignol monomers are precursors, all of which are methoxylated to various degrees: p-coumaryl alcohol, coniferyl alcohol, and sinapyl alcohol.
When copolymerized with related aromatic compounds, coniferyl alcohol forms lignin or lignans.

Paracoumaryl alcohol

coumaryl alcoholp''-coumaryl alcohol(C 9 H 10 O 2 ) n
Three monolignol monomers are precursors, all of which are methoxylated to various degrees: p-coumaryl alcohol, coniferyl alcohol, and sinapyl alcohol.
When polymerized, p-coumaryl alcohol forms lignin or lignans.

Sulfite process

sulfitesulfite pulpingsulphite process
In sulfite pulping, lignin is removed from wood pulp as lignosulfonates, for which many applications have been proposed.
The sulfite process produces wood pulp which is almost pure cellulose fibers by using various salts of sulfurous acid to extract the lignin from wood chips in large pressure vessels called digesters.

Lignosulfonates

lignosulfonatelignosulphonatelignosulphonates
In sulfite pulping, lignin is removed from wood pulp as lignosulfonates, for which many applications have been proposed.
Most delignification in sulfite pulping involves acidic cleavage of ether bonds, which connect many of the constituents of lignin.

Sinapyl alcohol

Three monolignol monomers are precursors, all of which are methoxylated to various degrees: p-coumaryl alcohol, coniferyl alcohol, and sinapyl alcohol.
This phytochemical is one of the monolignols, which are precursor to lignin or lignans.

Bryophyte

bryophytesBryophytamosses
Lignin is present in all vascular plants, but not in bryophytes, supporting the idea that the original function of lignin was restricted to water transport.

Vessel element

vesselsvessel elementsWood vessels
Lignin fills the spaces in the cell wall between cellulose, hemicellulose, and pectin components, especially in vascular and support tissues: xylem tracheids, vessel elements and sclereid cells.
The cell wall of a vessel element becomes strongly "lignified", i.e. it develops reinforcing material made of lignin.

Kraft process

kraftkraft pulpingkraft pulp mill
Lignin removed by the kraft process is usually burned for its fuel value, providing energy to power the mill.
The kraft process entails treatment of wood chips with a hot mixture of water, sodium hydroxide (NaOH), and sodium sulfide (Na 2 S), known as white liquor, that breaks the bonds that link lignin, hemicellulose, and cellulose.

Pulp (paper)

pulpwood pulppaper pulp
Mechanical, or high-yield pulp, which is used to make newsprint, still contains most of the lignin originally present in the wood.
Wood and other plant materials used to make pulp contain three main components (apart from water): cellulose fibers (desired for papermaking), lignin (a three-dimensional polymer that binds the cellulose fibres together) and hemicelluloses, (shorter branched carbohydrate polymers).

Xylem

cohesion-tension theoryprotoxylemtranspirational pull
Its most commonly noted function is the support through strengthening of wood (mainly composed of xylem cells and lignified sclerenchyma fibres) in vascular plants. Lignin fills the spaces in the cell wall between cellulose, hemicellulose, and pectin components, especially in vascular and support tissues: xylem tracheids, vessel elements and sclereid cells.
During the early Silurian, they developed specialized cells, which were lignified (or bore similar chemical compounds) to avoid implosion; this process coincided with cell death, allowing their innards to be emptied and water to be passed through them.

Lignum

He named the substance “lignine”, which is derived from the Latin word lignum, meaning wood.
* Lignin

Cell wall

cell wallsplant cell wallprimary cell wall
Lignins are particularly important in the formation of cell walls, especially in wood and bark, because they lend rigidity and do not rot easily. Lignin fills the spaces in the cell wall between cellulose, hemicellulose, and pectin components, especially in vascular and support tissues: xylem tracheids, vessel elements and sclereid cells. It is covalently linked to hemicellulose and therefore cross-links different plant polysaccharides, conferring mechanical strength to the cell wall and by extension the plant as a whole.
Often, other polymers such as lignin, suberin or cutin are anchored to or embedded in plant cell walls.

Polysaccharide

polysaccharidesheteropolysaccharidecomplex carbohydrates
It is covalently linked to hemicellulose and therefore cross-links different plant polysaccharides, conferring mechanical strength to the cell wall and by extension the plant as a whole.
Wood is largely cellulose and lignin, while paper and cotton are nearly pure cellulose.

Calliarthron

This would suggest that its original function was structural; it plays this role in the red alga Calliarthron, where it supports joints between calcified segments.
The genus has lignin and contains secondary cell walls, traits which are normally associated with the vascular plants.

Methoxy group

methoxyOCH 3 methoxyl
Three monolignol monomers are precursors, all of which are methoxylated to various degrees: p-coumaryl alcohol, coniferyl alcohol, and sinapyl alcohol.
Many natural products in plants, e.g. lignins, are generated via catalysis by caffeoyl-CoA O-methyltransferase.