vascular plant
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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 plants that comprise vegetation on Earth. Embryophyta is a clade within the Phragmoplastophyta, a larger clade that also includes several groups of green algae including the ...
with lignified tissues (the
xylem Xylem is one of the two types of transport 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 Amer ...

xylem
) for conducting water and minerals throughout the plant. They also have a specialized non-lignified tissue (the
phloem Phloem (, ) is the living biological tissue, tissue in vascular plants that transports the soluble Organic chemistry, organic Chemical substance, compounds made during photosynthesis and known as ''photosynthates'', in particular the sugar sucrose ...

phloem
) to conduct products of
photosynthesis File:Photosynthesis equation.svg, upright=1.8, Overall equation for the type of photosynthesis that occurs in plants Photosynthesis is a process used by plants and other organisms to Energy transformation, convert light energy into chemical energ ...

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 plants (plants with xylem and phloem) that reproduce via spores and have neither seeds nor flowers. They differ from mosses and other bryophytes by being vascular, ...

fern
s,
gymnosperm The gymnosperms ( Greek language, lit. revealed seeds) are a group of Spermatophyte, seed-producing plants that includes Pinophyta, conifers, cycads, ''Ginkgo'', and gnetophyta, gnetophytes, forming the clade Gymnospermae, the living members of ...
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 Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλά ...
(
flowering plant The flowering plants, also known as Angiospermae (), or Magnoliophyta (), are the most diverse group of Embryophyte, land plants, with 64 Order(biology), orders, 416 Family (biology), families, approximately 13,000 known Genus, genera and 300,000 ...

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 stalk, showing vascular bundles, which include both phloem and xylem. Image:BrambleLeaf_CrossPolarisedLight_Diagram.jpg, 250px, Detail of the vasculature of a bramble leaf. Vascular tissue is a complex conducting tissue (biology), tissue, formed ...
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 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 Amer ...

xylem
and
phloem Phloem (, ) is the living biological tissue, tissue in vascular plants that transports the soluble Organic chemistry, organic Chemical substance, compounds made during photosynthesis and known as ''photosynthates'', in particular the sugar sucrose ...

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 Cross section of celery stalk, showing vascular bundles, which include both phloem and xylem Detail of vascular bundle: closed, collateral vascular bundles of the stem axis of '' Zea mays'' A vascular bundle is a part of the transport system ...
. 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 generation or phase is the ''
sporophyte '' Tortula muralis''. In mosses, the gametophyte is the dominant generation, while the sporophytes consist of sporangium-bearing stalks growing from the tips of the gametophytes A sporophyte () is the diploid Ploidy () is the number of com ...
'', which produces
spore )'', growing on a thinned hybrid black poplar ''(Populus x canadensis)''. The last stage of the moss lifecycle is shown, where the sporophytes are visible before dispersion of their spores: the calyptra (1) is still attached to the capsule ( ...
s and is
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 eukaryotic chromosomes include packaging proteins called histones which, aided by ...
(having two sets of
chromosomes 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 chaperone proteins, bind to and condense the DNA molecule ...
per cell). (By contrast, the principal generation phase in non-vascular plants is the ''
gametophyte A gametophyte () is one of the two alternation of generations, alternating multicellular organism, multicellular phases in the life cycles of plants and algae. It is a haploid multicellular organism that develops from a haploid spore that has one ...
'', 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 Euphy ...
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 ta ...
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 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 Amer ...

xylem
. Organic compounds such as
sucrose Sucrose is a type of sugar Sugar is the generic name for Sweetness, sweet-tasting, soluble carbohydrates, many of which are used in food. Table sugar, granulated sugar, or regular sugar, refers to sucrose, a disaccharide composed of glucose a ...

sucrose
produced by
photosynthesis File:Photosynthesis equation.svg, upright=1.8, Overall equation for the type of photosynthesis that occurs in plants Photosynthesis is a process used by plants and other organisms to Energy transformation, convert light energy into chemical energ ...

photosynthesis
in leaves are distributed by the
phloem Phloem (, ) is the living biological tissue, tissue in vascular plants that transports the soluble Organic chemistry, organic Chemical substance, compounds made during photosynthesis and known as ''photosynthates'', in particular the sugar sucrose ...

phloem
sieve tube elements. The xylem consists of vessels in
flowering plant The flowering plants, also known as Angiospermae (), or Magnoliophyta (), are the most diverse group of Embryophyte, land plants, with 64 Order(biology), orders, 416 Family (biology), families, approximately 13,000 known Genus, genera and 300,000 ...

flowering plant
s and
tracheid Tracheids are elongated cell Cell most often refers to: * Cell (biology), the functional basic unit of life Cell may also refer to: Closed spaces * Monastic cell, a small room, hut, or cave in which a monk or religious recluse lives * Prison c ...
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 Wood is a porous and fibrous s ...

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, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts ...

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 File:LeafUndersideWithStomata.jpg, The underside of a leaf. In this species (''Tradescantia zebrina'') the guard cells of the stomata are green because they contain chlorophyll while the epidermal cells are chlorophyll-free and contain red pigme ...

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 and hydrophobicity interact in this attempt to cut a water droplet.">water_droplet.html" ;"title="hydrophobicity interact in this attempt to cut a water droplet">hydrophobicity interact in this attempt to cut a water droplet. ...

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, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts ...

water
molecule File:Pentacene on Ni(111) STM.jpg, A scanning tunneling microscopy image of pentacene molecules, which consist of linear chains of five carbon rings. A molecule is an electrically neutral group of two or more atoms held together by chemical bo ...

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 File:DiffusionMicroMacro.gif, 250px, Diffusion from a microscopic and macroscopic point of view. Initially, there are solute molecules on the left side of a barrier (purple line) and ...

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, a salt is a chemical compound consisting of an ionic assembly of cations and anions. Salts are composed of related numbers of cations (positively electric charge, charged ions) and anions (negatively charged ions) so that the prod ...

salts
.


Absorption

Living root cells passively absorb water in the absence of transpiration pull via
osmosis Osmosis (, ) is the spontaneous net movement or diffusion File:DiffusionMicroMacro.gif, 250px, Diffusion from a microscopic and macroscopic point of view. Initially, there are solute molecules on the left side of a barrier (purple line) and ...

osmosis
creating root pressure. It is possible for there to be no
evapotranspiration Evapotranspiration (ET) is the sum of water evaporation 280px, Demonstration of evaporative cooling. When the sensor is dipped in ethanol and then taken out to evaporate, the instrument shows progressively lower temperature as the ethanol eva ...

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 vapour (99.9839 °C) , - , Boiling point , , - , specific gas constant , 461.5 J/( kg·K) , - , Heat of vaporization , 2.27 MJ/kg , - , Heat capacity , 1.864 kJ/(kg·K) Water vapo ...

humidity
, darkness or drought.


Conduction

Xylem and
phloem Phloem (, ) is the living biological tissue, tissue in vascular plants that transports the soluble Organic chemistry, organic Chemical substance, compounds made during photosynthesis and known as ''photosynthates'', in particular the sugar sucrose ...

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 File:Photosynthesis equation.svg, upright=1.8, Overall equation for the type of photosynthesis that occurs in plants Photosynthesis is a process used by plants and other organisms to Energy transformation, convert light energy into chemical energ ...

photosynthesis
and transported to the growing shoots and roots (sinks) for use in growth,
cellular respiration upright=2.5, Typical eukaryotic cell 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 ...

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 nu ...
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