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Vascular plants (from Latin ''vasculum'': duct), also known as Tracheophyta (the tracheophytes , from Greek τραχεῖα ἀρτηρία ''trācheia artēria'' 'windpipe' + φυτά ''phutá'' 'plants'), form a large group of plants ( 300,000 accepted known species) which are
land plants The Embryophyta (), or land plants, are the most familiar group of green plant Plants are predominantly photosynthetic Photosynthesis is a process used by plants and other organisms to Energy transformation, convert light energy into ...
with lignified tissues (the
xylem Xylem is one of the two types of transport in s, the other being . The basic function of xylem is to transport from roots to stems and leaves, but it also transports . The word ''xylem'' is derived from the word (''xylon''), meaning "wood"; ...

xylem
) for conducting water and minerals throughout the plant. They also have a specialized non-lignified tissue (the
phloem Phloem (, ) is the living tissue Tissue may refer to: Biology * Tissue (biology), an ensemble of similar cells that together carry out a specific function * ''Triphosa haesitata'', a species of geometer moth found in North America * ''Triphosa d ...

phloem
) to conduct products of
photosynthesis Photosynthesis is a process used by plants and other organisms to into that, through , can later be released to fuel the organism's activities. Some of this chemical energy is stored in molecules, such as s and es, which are synthesized fro ...

photosynthesis
. Vascular plants include the
clubmoss Lycopodiopsida is a class of herbaceous vascular plants known as lycopods, lycophytes or other terms including the component lyco-. Members of the class are called clubmosses, firmosses and quillworts. They have dichotomously branching stems be ...
es,
horsetails ''Equisetum'' (; horsetail, snake grass, puzzlegrass) is the only living genus in Equisetaceae, a family (biology), family of vascular plants that reproduce by spores rather than seeds. ''Equisetum'' is a "living fossil", the only living genus o ...

horsetails
,
fern A fern (Polypodiopsida or Polypodiophyta ) is a member of a group of vascular plant Vascular plants (from Latin ''vasculum'': duct), also known as Tracheophyta (the tracheophytes , from Greek τραχεῖα ἀρτηρία ''trācheia art ...

fern
s,
gymnosperm The gymnosperms ( lit. revealed seeds) are a group of seed-producing plants that includes conifers Conifers are a group of cone-bearing seed plants, a subset of gymnosperms. Scientifically, they make up the division Pinophyta (), also ...
s (including
conifer Conifers are a group of conifer cone, cone-bearing Spermatophyte, seed plants, a subset of gymnosperms. Scientifically, they make up the phylum, division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single ex ...
s) and
angiosperms Flowering plants include multiple members of the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greec ...
(
flowering plant Flowering plants include multiple members of the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greec ...

flowering plant
s). Scientific names for the group include Tracheophyta, Tracheobionta and Equisetopsida ''sensu lato''. Some early land plants (the
rhyniophyte The rhyniophytes are a group of extinct early vascular plant Vascular plants (from Latin ''vasculum'': duct), also known as Tracheophyta (the tracheophytes , from the Greek ''trācheia''), form a large group of plants ( 300,000 accepted known sp ...
s) had less developed vascular tissue; the term eutracheophyte has been used for all other vascular plants, including all living ones.


Characteristics

Botanists define vascular plants by three primary characteristics: # Vascular plants have
vascular tissue Vascular tissue is a complex conducting tissue Tissue may refer to: Biology * Tissue (biology), an ensemble of similar cells that together carry out a specific function * ''Triphosa haesitata'', a species of geometer moth found in North Ameri ...
s which distribute resources through the plant. Two kinds of vascular tissue occur in plants:
xylem Xylem is one of the two types of transport in s, the other being . The basic function of xylem is to transport from roots to stems and leaves, but it also transports . The word ''xylem'' is derived from the word (''xylon''), meaning "wood"; ...

xylem
and
phloem Phloem (, ) is the living tissue Tissue may refer to: Biology * Tissue (biology), an ensemble of similar cells that together carry out a specific function * ''Triphosa haesitata'', a species of geometer moth found in North America * ''Triphosa d ...

phloem
. Phloem and xylem are closely associated with one another and are typically located immediately adjacent to each other in the plant. The combination of one xylem and one phloem strand adjacent to each other is known as a
vascular bundle A vascular bundle is a part of the transport system in vascular plant Vascular plants (from Latin ''vasculum'': duct), also known as Tracheophyta (the tracheophytes , from Greek τραχεῖα ἀρτηρία ''trācheia artēria'' 'wind ...
. The
evolution Evolution is change in the heritable Heredity, also called inheritance or biological inheritance, is the passing on of Phenotypic trait, traits from parents to their offspring; either through asexual reproduction or sexual reproduction, ...

evolution
of vascular tissue in plants allowed them to evolve to larger sizes than
non-vascular plant Non-vascular plants are plant Plants are mainly multicellular organisms, predominantly photosynthetic Photosynthesis is a process used by plants and other organisms to Energy transformation, convert light energy into chemical energy t ...
s, which lack these specialized conducting tissues and are thereby restricted to relatively small sizes. # In vascular plants, the principal is the ''
sporophyte 350px, Sporophytes of moss during spring A sporophyte () is the diploid Ploidy () is the number of complete sets of chromosome A chromosome is a long DNA molecule with part or all of the genetic material of an organism. Most eukaryo ...
'', which produces
spore )'', growing on a thinning, thinned hybrid black poplar ''(populus, Populus x canadensis)''. The last stage of the moss#Life cycle, moss lifecycle is shown, where the sporophytes are visible before dispersion of their spores: the calyptra (1) is ...
s and is
diploid Ploidy () is the number of complete sets of chromosomes in a cell (biology), cell, and hence the number of possible alleles for Autosome, autosomal and Pseudoautosomal region, pseudoautosomal genes. Sets of chromosomes refer to the number of mate ...
(having two sets of
chromosomes A chromosome is a long DNA molecule with part or all of the genome, genetic material of an organism. Most eukaryotic chromosomes include packaging proteins called histones which, aided by Chaperone (protein), chaperone proteins, bind to and D ...
per cell). (By contrast, the principal generation phase in non-vascular plants is the ''
gametophyte A gametophyte () is one of the two alternating multicellular phases in the life cycles of plant Plants are predominantly photosynthetic eukaryotes of the Kingdom (biology), kingdom Plantae. Historically, the plant kingdom encompassed all ...
'', which produces
gametes A gamete ( /ˈɡæmiːt/; from Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the foll ...
and is
haploid Ploidy () is the number of complete sets of chromosome A chromosome is a long DNA molecule with part or all of the genetic material of an organism. Most eukaryotic chromosomes include packaging proteins called histones which, aided by ...
- with one set of chromosomes per cell.) # Vascular plants have true roots, leaves, and stems, even if some groups have secondarily lost one or more of these traits. Cavalier-Smith (1998) treated the Tracheophyta as a
phylum In biology, a phylum (; plural The plural (sometimes list of glossing abbreviations, abbreviated ), in many languages, is one of the values of the grammatical number, grammatical category of number. The plural of a noun typically denotes a q ...
or botanical division encompassing two of these characteristics defined by the Latin phrase "facies diploida xylem et phloem instructa" (diploid phase with xylem and phloem). One possible mechanism for the presumed evolution from emphasis on haploid generation to emphasis on diploid generation is the greater efficiency in spore dispersal with more complex diploid structures. Elaboration of the spore stalk enabled the production of more spores and the development of the ability to release them higher and to broadcast them farther. Such developments may include more photosynthetic area for the spore-bearing structure, the ability to grow independent roots, woody structure for support, and more branching.


Phylogeny

A proposed phylogeny of the vascular plants after Kenrick and Crane 1997 is as follows, with modification to the gymnosperms from Christenhusz ''et al.'' (2011a), Pteridophyta from Smith ''et al.'' and lycophytes and ferns by Christenhusz ''et al.'' (2011b) The cladogram distinguishes the
rhyniophyte The rhyniophytes are a group of extinct early vascular plant Vascular plants (from Latin ''vasculum'': duct), also known as Tracheophyta (the tracheophytes , from the Greek ''trācheia''), form a large group of plants ( 300,000 accepted known sp ...
s from the "true" tracheophytes, the eutracheophytes. This phylogeny is supported by several molecular studies. Other researchers state that taking fossils into account leads to different conclusions, for example that the ferns (Pteridophyta) are not monophyletic. Hao and Xue presented an alternative phylogeny in 2013 for pre-
euphyllophyte The euphyllophytes are a clade of plants within the Vascular plant, tracheophytes (the vascular plants). The group may be treated as an unranked clade, a Phylum, division under the name Euphyllophyta or a Subphylum, subdivision under the name Eup ...
plants.


Nutrient distribution

Water and
nutrient A nutrient is a substance Substance may refer to: * Substance (Jainism), a term in Jain ontology to denote the base or owner of attributes * Chemical substance, a material with a definite chemical composition * Matter, anything that has mass and t ...
s in the form of inorganic solutes are drawn up from the soil by the roots and transported throughout the plant by the
xylem Xylem is one of the two types of transport in s, the other being . The basic function of xylem is to transport from roots to stems and leaves, but it also transports . The word ''xylem'' is derived from the word (''xylon''), meaning "wood"; ...

xylem
. Organic compounds such as
sucrose Sucrose is a type of sugar Sugar is the generic name for , soluble s, many of which are used in food. Simple sugars, also called s, include , , and . Compound sugars, also called s or double sugars, are molecules made of two monosacchari ...

sucrose
produced by
photosynthesis Photosynthesis is a process used by plants and other organisms to into that, through , can later be released to fuel the organism's activities. Some of this chemical energy is stored in molecules, such as s and es, which are synthesized fro ...

photosynthesis
in leaves are distributed by the
phloem Phloem (, ) is the living tissue Tissue may refer to: Biology * Tissue (biology), an ensemble of similar cells that together carry out a specific function * ''Triphosa haesitata'', a species of geometer moth found in North America * ''Triphosa d ...

phloem
sieve tube elements. The xylem consists of vessels in
flowering plant Flowering plants include multiple members of the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greec ...

flowering plant
s and
tracheid A tracheid is a long and tapered lignified cell in the xylem Xylem is one of the two types of transport in s, the other being . The basic function of xylem is to transport from roots to stems and leaves, but it also transports . The word ' ...
s in other vascular plants, which are dead hard-walled hollow cells arranged to form files of tubes that function in water transport. A tracheid cell wall usually contains the polymer
lignin Lignin is a class of complex organic polymers that form key structural materials in the support tissues of most plants. Lignins are particularly important in the formation of cell walls, especially in wood and Bark (botany), bark, because they l ...

lignin
. The phloem, however, consists of living cells called sieve-tube members. Between the sieve-tube members are sieve plates, which have pores to allow molecules to pass through. Sieve-tube members lack such organs as
nuclei ''Nucleus'' (plural nuclei) is a Latin word for the seed inside a fruit. It most often refers to: *Atomic nucleus, the very dense central region of an atom *Cell nucleus, a central organelle of a eukaryotic cell, containing most of the cell's DNA ...

nuclei
or
ribosomes Ribosomes () are molecular machine, macromolecular machines, found within all living cell (biology), cells, that perform Translation (biology), biological protein synthesis (mRNA translation). Ribosomes link amino acids together in the order spec ...

ribosomes
, but cells next to them, the companion cells, function to keep the sieve-tube members alive.


Transpiration

The most abundant
compound Compound may refer to: Architecture and built environments * Compound (enclosure), a cluster of buildings having a shared purpose, usually inside a fence or wall ** Compound (fortification), a version of the above fortified with defensive structu ...
in all plants, as in all cellular organisms, is
water Water (chemical formula H2O) is an Inorganic compound, inorganic, transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known li ...

water
, which serves an important structural role and a vital role in plant metabolism.
Transpiration in a tomato The tomato is the edible berry of the plant ''Solanum lycopersicum'', commonly known as a tomato plant. The species originated in western South America South America is a continent entirely in the Western Hemisphere ...

Transpiration
is the main process of water movement within plant tissues. Water is constantly transpired from the plant through its
stomata In botany Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in this field. The term "botany" comes from the ...

stomata
to the atmosphere and replaced by soil water taken up by the roots. The movement of water out of the leaf stomata creates a transpiration pull or tension in the water column in the xylem vessels or tracheids. The pull is the result of water
surface tension Surface tension is the tendency of liquid A liquid is a nearly incompressible In fluid mechanics Fluid mechanics is the branch of physics concerned with the mechanics Mechanics (Ancient Greek, Greek: ) is the area of physi ...

surface tension
within the cell walls of the mesophyll cells, from the surfaces of which evaporation takes place when the stomata are open.
Hydrogen bonds A hydrogen bond (or H-bond) is a primarily Electrostatics, electrostatic force of attraction between a hydrogen Hydrogen is the chemical element Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodic table of ...
exist between
water Water (chemical formula H2O) is an Inorganic compound, inorganic, transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known li ...

water
molecule A molecule is an electrically Electricity is the set of physical phenomena associated with the presence and motion Image:Leaving Yongsan Station.jpg, 300px, Motion involves a change in position In physics, motion is the phenomenon ...

molecule
s, causing them to line up; as the molecules at the top of the plant evaporate, each pulls the next one up to replace it, which in turn pulls on the next one in line. The draw of water upwards may be entirely passive and can be assisted by the movement of water into the roots via
osmosis Osmosis (, ) is the spontaneous net movement or diffusion Diffusion is the net movement of anything (for example, atoms, ions, molecules, energy) generally from a region of higher concentration In chemistry Chemistry is the ...

osmosis
. Consequently, transpiration requires very little energy to be used by the plant. Transpiration assists the plant in absorbing nutrients from the soil as soluble
salts In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, properties, behavior and the changes they undergo during ...

salts
.


Absorption

Living root cells passively absorb water in the absence of transpiration pull via
osmosis Osmosis (, ) is the spontaneous net movement or diffusion Diffusion is the net movement of anything (for example, atoms, ions, molecules, energy) generally from a region of higher concentration In chemistry Chemistry is the ...

osmosis
creating root pressure. It is possible for there to be no
evapotranspiration Evapotranspiration (ET) is the sum of water evaporation and transpiration from a surface area to the Atmosphere of Earth, atmosphere. Evaporation accounts for the movement of water to the air from sources such as the soil, canopy interception, and ...

evapotranspiration
and therefore no pull of water towards the shoots and leaves. This is usually due to high temperatures, high
humidity Humidity is the concentration of water vapor, water vapour present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation (meteorology), precipitation, d ...

humidity
, darkness or drought.


Conduction

Xylem and
phloem Phloem (, ) is the living tissue Tissue may refer to: Biology * Tissue (biology), an ensemble of similar cells that together carry out a specific function * ''Triphosa haesitata'', a species of geometer moth found in North America * ''Triphosa d ...

phloem
tissues are involved in the conduction processes within plants. Sugars are conducted throughout the plant in the phloem, water and other nutrients through the xylem. Conduction occurs from a source to a sink for each separate nutrient. Sugars are produced in the leaves (a source) by
photosynthesis Photosynthesis is a process used by plants and other organisms to into that, through , can later be released to fuel the organism's activities. Some of this chemical energy is stored in molecules, such as s and es, which are synthesized fro ...

photosynthesis
and transported to the growing shoots and roots (sinks) for use in growth,
cellular respiration Cellular respiration is a set of metabolic Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life Life is a characteristic that distinguishes physical entities that have biological processes, such a ...

cellular respiration
or storage. Minerals are absorbed in the roots (a source) and transported to the shoots to allow cell division and growth.Chapters 5, 6 and 10
Taiz and Zeiger Taiz ( ar, تَعِزّ, Taʿizz) is a city in southwestern Yemen ) , image_map = File:Yemen on the globe (Yemen centered).svg , map_caption = , image_map2 = , capital = Sana'a (''Houthi takeover in Yemen, De jure'')Aden (Temporary capita ...
''Plant Physiology'' 3rd Edition SINAUER 2002


See also

*
Fern allies '', from the Equisetopsida (horsetails) Image:Psilotum.jpg, ''Psilotum nudum'', from the Psilotopsida (whisk ferns) Fern allies are a diverse group of seedless vascular plants that are not true ferns. Like ferns, a fern ally disperses by shedding ...
*
Bryophyte Bryophytes are an informal group consisting of three divisions Division or divider may refer to: Mathematics *Division (mathematics) Division is one of the four basic operations of arithmetic, the ways that numbers are combined to make new n ...

Bryophyte
s *
Non-vascular plant Non-vascular plants are plant Plants are mainly multicellular organisms, predominantly photosynthetic Photosynthesis is a process used by plants and other organisms to Energy transformation, convert light energy into chemical energy t ...
*
Pteridophyte A pteridophyte is a vascular plant (with xylem and phloem) that disperses spores. Because pteridophytes produce neither flowers nor seeds, they are sometimes referred to as "cryptogams", meaning that their means of reproduction is hidden. Ferns, h ...


References


Bibliography

* * * * , in


External links


“Higher plants” or “vascular plants”?
{{Authority control Plants Extant Silurian first appearances