Vascular plant

Botanists define vascular plants by three primary characteristics:

1. Vascular plants have vascular tissues which distribute resources through the plant. Two kinds of vascular tissue occur in plants: xylem and 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.{{cite web |url=https://basicbiology.net/plants/physiology/xylem-phloem |title=Xylem and Phloem |website=Basic Biology |date=26 August 2020}} The evolution of vascular tissue in plants allowed them to evolve to larger sizes than non-vascular plants, which lack these specialized conducting tissues and are thereby restricted to relatively small sizes.
2. In vascular plants, the principal generation or phase is the sporophyte, which produces spores and is diploid (having two sets of chromosomes per cell). (By contrast, the principal generation phase in non-vascular plants is the gametophyte, which produces gametes and is haploid, with one set of chromosomes per cell.)
3. 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 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).{{rp|251}}

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 further. 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.{{citation needed|reason=several points in this paragraph are conjectural and need WP:RS|date=February 2016}}

Sexual reproduction in vascular land plants involves the process of meiosis. Meiosis provides a direct DNA repair capability for dealing with DNA damages, including oxidative DNA damages, in germline reproductive tissues.{{cite journal |vauthors=Hörandl E |title=Apomixis and the paradox of sex in plants |journal=Ann Bot |volume=134 |issue=1 |pages=1–18 |date=June 2024 |pmid=38497809 |doi=10.1093/aob/mcae044 |url=|doi-access=free |pmc=11161571 }}

A proposed phylogeny of the vascular plants after Kenrick and Crane 1997{{cite book|last1=Kenrick |first1=Paul |first2=Peter R. |last2=Crane |date=1997 |title=The Origin and Early Diversification of Land Plants: A Cladistic Study |location=Washington, D.C. |publisher=Smithsonian Institution Press |isbn=1-56098-730-8}} is as follows, with modification to the gymnosperms from Christenhusz et al. (2011a),{{cite journal |last1=Christenhusz |first1=Maarten J. M. |last2=Reveal |first2=James L. |last3=Farjon |first3=Aljos |last4=Gardner |first4=Martin F. |last5=Mill |first5=R.R. |last6=Chase |first6=Mark W. |year=2011 |title=A new classification and linear sequence of extant gymnosperms |journal=Phytotaxa |volume=19 |pages=55–70 |doi=10.11646/phytotaxa.19.1.3 }} Pteridophyta from Smith et al.{{cite journal |last1=Smith |first1=Alan R. |last2=Pryer |first2=Kathleen M. |last3=Schuettpelz |first3=E. |last4=Korall |first4=P. |last5=Schneider |first5=H. |last6=Wolf |first6=Paul G. |year=2006 |title=A classification for extant ferns |journal=Taxon |volume=55 |issue=3 |pages=705–731 |doi=10.2307/25065646 |jstor=25065646 }} and lycophytes and ferns by Christenhusz et al. (2011b) {{cite journal |last1=Christenhusz |first1=Maarten J. M. |last2=Zhang|first2=Xian-Chun |last3=Schneider |first3=Harald |year=2011 |title=A linear sequence of extant families and genera of lycophytes and ferns |journal=Phytotaxa |volume=19 |pages=7–54 |doi=10.11646/phytotaxa.19.1.2 }} The cladogram distinguishes the rhyniophytes from the "true" tracheophytes, the eutracheophytes.

{{Barlabel|size=17|at1=13.5|bar1=green|style=font-size:75%;line-height:75%|label1=Gymnosperms|cladogram={{clade

|label1=Polysporangiates

|1={{clade

|1=†Aglaophyton

|2=†Horneophytopsida

|3={{clade

|label1=Tracheophyta

|1={{clade

|1=†Rhyniophyta

|label2=Eutracheophytes

|2={{clade

|label1=Lycophytina

|1={{clade

|1=Lycopodiophyta

|2=†Zosterophyllophyta

}}

|label2=Euphyllophytina

|2={{clade

|label1=Pteridophyta

|1={{clade

|1={{clade

|1=†Cladoxylopsida

|2=Equisetopsida (horsetails)

|3=Marattiopsida

|4=Psilotopsida (whisk ferns and adders'-tongues)

|5=Pteridopsida (true ferns)

}}

}}

|label2=Lignophytes

|2={{clade

|1=†Progymnospermophyta

|label2=Spermatophytes

|2={{clade

|1=Cycadophyta (cycads)|barbegin1=green

|2=Ginkgophyta (ginkgo)|bar2=green

|3=Gnetophyta|bar3=green

|4=Pinophyta (conifers)|barend4=green

|5=Magnoliophyta (flowering plants)

|6=†Pteridospermatophyta (seed ferns)

}}

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This phylogeny is supported by several molecular studies.{{cite journal |last1=Pryer |first1=K. M. |last2=Schneider |first2=H. |year=2001 |title=Horsetails and ferns are a monophyletic group and the closest living relatives to seed plants |journal=Nature |volume=409 |issue=6820 |pages=618–22 |doi=10.1038/35054555 |pmid=11214320 |last3=Smith |first3=A. R. |last4=Cranfill |first4=R. |last5=Wolf |first5=P. G. |last6=Hunt |first6=J. S. |last7=Sipes |first7=S. D. |bibcode=2001Natur.409..618S }}{{cite journal |last1=Pryer |first1=K. M. |last2=Schuettpelz |first2=E. |last3=Wolf |first3=P. G. |last4=Schneider |first4=H. |last5=Smith |first5=A. R. |last6=Cranfill |first6=R. |year=2004 |title=Phylogeny and evolution of ferns (monilophytes) with a focus on the early leptosporangiate divergences |journal=American Journal of Botany |volume=91 |issue=10|pages=1582–1598 |doi=10.3732/ajb.91.10.1582 |pmid=21652310 }} Other researchers state that taking fossils into account leads to different conclusions, for example that the ferns (Pteridophyta) are not monophyletic.{{Cite journal |last1=Rothwell |first1=G. W. |last2=Nixon |first2=K. C. |year=2006 |title=How Does the Inclusion of Fossil Data Change Our Conclusions about the Phylogenetic History of Euphyllophytes? |journal=International Journal of Plant Sciences |volume=167 |issue=3 |pages=737–749 |doi=10.1086/503298 |name-list-style=amp }}

Hao and Xue presented an alternative phylogeny in 2013 for pre-euphyllophyte plants.{{cite book |last1=Hao |first1=Shougang |last2=Xue |first2=Jinzhuang |title=The Early Devonian Posongchong Flora of Yunnan: A Contribution to an Understanding of the Evolution and Early Diversification of Vascular Plants |date=2013 |publisher=Science Press |isbn=978-7-03-036616-0 }}{{page needed|date=October 2024}}

{{Barlabel|size=27

|at1=5|label1=Rhyniopsids|bar1=#b88

|at2=8|label2=Renalioids|bar2=#aca

|cladogram=

{{clade|style=font-size:80%;line-height:80%

|label1=Polysporangiophytes

|1={{clade

|1=†Horneophytaceae 30px

|label2=Tracheophytes

|2={{clade

|1=†Cooksoniaceae

|2={{clade

|1=†Aglaophyton

|2={{clade

|1=†Rhyniopsida 50px |barbegin1=#b88

|2={{clade

|1=†Catenalis|barend1=#b88

|2={{clade

|1=†Aberlemnia|barbegin1=#aca

|2={{clade

|1=†Hsuaceae|bar1=#aca

|2={{clade

|1=†Renaliaceae 40px |barend1=#aca

|label2=Eutracheophytes

|2={{clade

|1={{clade

|1=†Adoketophyton

|2=†?Barinophytopsida

|3=†Zosterophyllopsida

}}

|2={{clade

|label1=Microphylls

|1={{clade

|1=†Hicklingia

|2={{clade

|1=†Gumuia

|2={{clade

|1=†Nothia

|2={{clade

|1=Lycopodiopsida 40px

|2=†Zosterophyllum deciduum

}}

}}

}}

}}

|2={{clade

|1=†Yunia

|label2=Euphyllophytes

|2={{clade

|1=†Eophyllophyton

|2={{clade

|1=†Trimerophytopsida

|label2=Megaphylls

|2={{clade

|label1=Moniliformopses

|1={{clade

|1=†Ibyka

|2={{clade

|1=†Pauthecophyton

|2={{clade

|1=†Cladoxylopsida

|2=Polypodiopsida 40px

}}

}}

}}

|label2=Radiatopses

|2={{clade

|1=†Celatheca

|2={{clade

|1=†Pertica

|label2=Lignophytes

|2={{clade

|1=†Progymnosperms
(paraphyletic)

|2=Spermatophytes 30px

}}

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File:ficusxylem.jpg elements in the shoot of a fig tree (Ficus alba), crushed in hydrochloric acid ]]

Water and nutrients in the form of inorganic solutes are drawn up from the soil by the roots and transported throughout the plant by the xylem. Organic compounds such as sucrose produced by photosynthesis in leaves are distributed by the phloem sieve-tube elements.{{cn|date=January 2025}}

The xylem consists of vessels in flowering plants and of tracheids in other vascular plants. Xylem cells 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.{{cn|date=January 2025}}

The phloem, on the other hand, 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 or ribosomes, but cells next to them, the companion cells, function to keep the sieve-tube members alive.{{cn|date=January 2025}}

The most abundant compound in all plants, as in all cellular organisms, is water, which has an important structural role and a vital role in plant metabolism. Transpiration is the main process of water movement within plant tissues. Plants constantly transpire water through their stomata to the atmosphere and replace that water with soil moisture taken up by their roots. When the stomata are closed at night, water pressure can build up in the plant. Excess water is excreted through pores known as hydathodes.{{Cite web|url=https://ipm.missouri.edu/MEG/2009/6/Guttation-A-Pressure-Relief-for-Plants/index.cfm|title=Guttation: A Pressure Relief for Plants (Christopher Starbuck)|website=ipm.missouri.edu}} The movement of water out of the leaf stomata sets up transpiration pull or tension in the water column in the xylem vessels or tracheids. The pull is the result of water 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 exist between water molecules, 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. Consequently, transpiration requires the plant to expend very little energy on water movement. Transpiration assists the plant in absorbing nutrients from the soil as soluble salts. Transpiration plays an important role in the absorption of nutrients from the soil as soluble salts are transported along with the water from the soil to the leaves. Plants can adjust their transpiration rate to optimize the balance between water loss and nutrient absorption.{{Cite journal |last1=Raven |first1=J. A. |last2=Edwards |first2=D. |date=2001-03-01 |title=Roots: evolutionary origins and biogeochemical significance |journal=Journal of Experimental Botany |volume=52 |issue=suppl 1 |pages=381–401 |doi=10.1093/jexbot/52.suppl_1.381 |pmid=11326045 |doi-access=free }}

Living root cells passively absorb water. Pressure within the root increases when transpiration demand via osmosis is low and decreases when water demand is high. No water movement towards the shoots and leaves occurs when evapotranspiration is absent. This condition is associated with high temperature, high humidity, darkness, and drought.{{Citation needed|date=July 2018}}

Xylem is the water-conducting tissue, and the secondary xylem provides the raw material for the forest products industry.{{cite journal |last1=Zhao |first1=Chengsong |last2=Craig |first2=Johanna C. |last3=Petzold |first3=H. Earl |last4=Dickerman |first4=Allan W. |last5=Beers |first5=Eric P. |title=The Xylem and Phloem Transcriptomes from Secondary Tissues of the Arabidopsis Root-Hypocotyl |journal=Plant Physiology |date=June 2005 |volume=138 |issue=2 |pages=803–818 |doi=10.1104/pp.105.060202 |pmc=1150398 |pmid=15923329 }} Xylem and phloem tissues each play a part in the conduction processes within plants. Sugars are conveyed throughout the plant in the phloem; water and other nutrients pass 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 and transported to the growing shoots and roots (sinks) for use in growth, cellular respiration or storage. Minerals are absorbed in the roots (a source) and transported to the shoots to allow cell division and growth.{{cite book |last1=Taiz |first1 =Lincoln |last2=Zeiger |first2 =Eduardo |author-link2 =Eliezer (Eduardo) Zeiger |chapter =5, 6, 10

|title=Plant Physiology |edition =3 |location =Sunderland, Massachusetts

|publisher =Sinauer Associates |publication-date =2002

|page = |isbn = }}

{{Cite journal |last=Doyle |first=James A. |title=Phylogeny of Vascular Plants |date=1998 |journal=Annual Review of Ecology and Systematics |volume=29 |issue=1 |pages=567–599 |doi=10.1146/annurev.ecolsys.29.1.567 }}{{Cite journal |last1=Heijmans |first1=Monique M. P. D. |last2=Arp |first2=Wim J. |last3=Berendse |first3=Frank |date=October 2001 |title=Effects of elevated CO 2 and vascular plants on evapotranspiration in bog vegetation: EVAPOTRANSPIRATION IN BOG VEGETATION |journal=Global Change Biology |language=en |volume=7 |issue=7 |pages=817–827 |doi=10.1046/j.1354-1013.2001.00440.x }}

• Fern allies
• Bryophytes
• Non-vascular plant
• Pteridophyte

{{Reflist|30em}}

{{Refbegin}}

• {{cite book |editor-last1=Cracraft |editor-first1=Joel |editor-link1=Joel Cracraft |editor-last2=Donoghue |editor-first2=Michael J. |editor-link2=Michael Donoghue |title=Assembling the Tree of Life |url=https://books.google.com/books?id=6lXTP0YU6_kC |date=2004 |publisher=Oxford University Press |isbn=978-0-19-972960-9}}
• {{cite journal |last1=Cantino |first1=Philip D. |last2=Doyle |first2=James A. |last3=Graham |first3=Sean W. |last4=Judd |first4=Walter S. |author-link4=Walter S. Judd |last5=Olmstead |first5=Richard G. |last6=Soltis |first6=Douglas E. |author-link6=Douglas Soltis |last7=Soltis |first7=Pamela S. |author-link7=Pamela Soltis |last8=Donoghue |first8=Michael J. |author-link8=Michael Donoghue |title=Towards a Phylogenetic Nomenclature of Tracheophyta |journal=Taxon |date=1 August 2007 |volume=56 |issue=3 |pages=822 |doi=10.2307/25065865 |jstor=25065865 |ref=none}}
• {{cite journal |last1=Kenrick |first1=P. |title=The relationships of vascular plants |journal=Philosophical Transactions of the Royal Society B: Biological Sciences |date=29 June 2000 |volume=355 |issue=1398 |pages=847–855 |doi=10.1098/rstb.2000.0619 |pmc=1692788 |pmid=10905613 |ref=none}}
• {{cite book |last1=Pryer |first1=Kathleen M. |last2=Schneider |first2=Harald |last3=Magallon |first3=Susana |title=The radiation of vascular plants |date=13 November 2017 |pages=138–153 |url=https://sites.duke.edu/pryerlab/files/2017/10/Pryer-et-al.ToL2_.2004.pdf |ref=none}}, in {{harvtxt |Cracraft |Donoghue |2004}}

{{Refend}}

• [https://biology.stackexchange.com/questions/68161/higher-plants-or-vascular-plants "Higher plants" or "vascular plants"?]

{{Plant classification}}

{{Botany}}

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Category:Plants

Category:Extant Silurian first appearances