Jump to content

Lycopodiopsida

From Wikipedia, the free encyclopedia
(Redirected fromClubmoss)
This article is about a group of plants that excludes the extinct zosterophylls. For the more broadly defined group that includes the zosterophylls, seeLycophyte.
"Lycopod" redirects here. For other uses, seeLycopod (disambiguation).

Lycopodiopsida
Temporal range:Devonian–Recent
Palhinhaea cernuawith close-up of branch
Scientific classificationEdit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Lycophytes
Class: Lycopodiopsida
Bartl.
Orders
Synonyms

SeeTable 1.

Lycopodiopsidais a class ofvascular plantsalso known aslycopodsorlycophytes.Members of the class are also calledclubmosses,firmosses,spikemossesandquillworts.They have dichotomously branching stems bearing simple leaves calledmicrophyllsand reproduce by means ofsporesborne insporangiaon the sides of the stems at the bases of the leaves. Although living species are small, during theCarboniferous,extinct tree-like forms (Lepidodendrales) formed huge forests that dominated the landscape and contributed tocoaldeposits.

The nomenclature and classification of plants with microphylls varies substantially among authors. A consensus classification for extant (living) species was produced in 2016 by thePteridophyte Phylogeny Group(PPG I), which places them all in the class Lycopodiopsida, which includes the classesIsoetopsidaandSelaginellopsidaused in other systems. (SeeTable 2.) Alternative classification systems have used ranks from division (phylum) to subclass. In the PPG I system, the class is divided into three orders,Lycopodiales,IsoetalesandSelaginellales.

Characteristics

[edit]

Club-mosses (Lycopodiales) are homosporous, but the generaSelaginella(spikemosses) andIsoetes(quillworts) are heterosporous, with female spores larger than the male.[1]As a result of fertilisation, the female gametophyte produces sporophytes. A few species ofSelaginellasuch asS. apodaandS. rupestrisare alsoviviparous;the gametophyte develops on the mother plant, and only when the sporophyte's primary shoot and root is developed enough for independence is the new plant dropped to the ground.[2]Many club-mossgametophytesaremycoheterotrophicand long-lived, residing underground for several years before emerging from the ground and progressing to thesporophytestage.[3]

Lycopodiaceae and spikemosses (Selaginella) are the only vascular plants with biflagellate sperm, an ancestral trait in land plants otherwise only seen inbryophytes.The only exceptions areIsoetesandPhylloglossum,which independently has evolved multiflagellated sperm cells with approximately 20 flagella[4][5](sperm flagella in other vascular plants can count at least thousand, but is completely absent in seed plants except for Ginkgo and cycads).[6]Because only two flagella puts a size limit on the genome, we find the largest known genomes in the clade inIsoetes,as multiflagellated sperm is not exposed for the same selection pressure as biflagellate sperm in regard of size.[7]

Taxonomy

[edit]

Phylogeny

[edit]

The extant lycophytes arevascular plants(tracheophytes) withmicrophyllous leaves,distinguishing them from theeuphyllophytes(plants withmegaphyllous leaves). The sister group of the extant lycophytes and their closest extinct relatives are generally believed to be thezosterophylls,aparaphyleticorplesiongroup. Ignoring some smaller extinct taxa, the evolutionary relationships are as shown below.[8][9][10]

tracheophytes
lycophytes
†zosterophylls

 (multiple branches,incertae sedis)

lycopodiopsida

 living lycophytes and
 their extinct close relatives

 (broadly defined) 
euphyllophytes

 ferns&horsetails

 spermatophytes
 (seed plants)

 (vascular plants) 

As of 2019,there was broad agreement, supported by both molecular and morphological evidence, that the extant lycophytes fell into three groups, treated as orders in PPG I, and that these, both together and individually, aremonophyletic,being related as shown in the cladogram below:[10]

 extant lycophytes 

Classification

[edit]

The rank and name used for the taxon holding the extant lycophytes (and their closest extinct relatives) varies widely. Table 1 below shows some of the highest ranks that have been used. Systems may use taxa at a rank lower than the highest given in the table with the same circumscription; for example, a system that uses Lycopodiophyta as the highest ranked taxon may place all of its members in a single subclass.

Table 1: Alternative highest ranks used which include only extant species and their closest relatives
Highest rank Name Example sources
Division (phylum) Lycophyta Taylor et al. (2009),[11]Mauseth (2014)[9]
Division (phylum) Lycopodiophyta Niklas (2016)[12]
Subdivision (subphylum) Lycopodiophytina Ruggiero et al. (2015)[13]
Class Lycopsida Kenrick & Crane (1997)[8][14]
Class Lycopodiopsida PPG I (2016)[10]
Subclass Lycopodiidae Chase & Reveal (2009)[15]

Some systems use a higher rank for a more broadly defined taxon of lycophytes that includes some extinct groups more distantly related to extant lycophytes, such as thezosterophylls.For example, Kenrick & Crane (1997) use the subdivision Lycophytina for this purpose, with all extant lycophytes falling within the class Lycopsida.[8]Other sources exclude the zosterophylls from any "lycophyte" taxon.[11]

In thePteridophyte Phylogeny Groupclassification of 2016 (PPG I), the three orders are placed in a single class, Lycopodiopsida, holding all extant lycophyte species. Older systems have used either three classes, one for each order, or two classes, recognizing the closer relationship between Isoetales and Selaginellales. In these cases, a higher ranked taxon is needed to contain the classes (see Table 1). As Table 2 shows, the names "Lycopodiopsida" and "Isoetopsida" are both ambiguous.

Table 2: Alternative arrangements of the orders of extant lycophytes into classes
Order 3 classes
e.g.IUCN Red List,2004[16]		 2 classes
e.g. Yatsentyuk et al. (2001)[17]		 1 class
PPG I[10]
Lycopodiales Lycopodiopsida Lycopodiopsida Lycopodiopsida
Isoetales Isoetopsida Isoetopsida
Selaginellales Sellaginellopsida

Subdivisions

[edit]

The PPG I system divides up the extant lycophytes as shown below.

  • Class LycopodiopsidaBartl.(3 orders)

Some extinct groups, such aszosterophylls,fall outside the limits of the taxon as defined by the classifications in Table 1 above. However, other extinct groups fall within somecircumscriptionsof this taxon. Taylor et al. (2009) and Mauseth (2014) include a number of extinct orders in their division (phylum) Lycophyta, although they differ on the placement of some genera.[11][9]The orders included by Taylor et al. are:[11]

Mauseth uses the order †Asteroxylales, placingBaragwanathiain the Protolepidodendrales.[9]

The relationship between some of these extinct groups and the extant ones was investigated by Kenrick and Crane in 1997. When the genera they used are assigned to orders, their suggested relationship is:[18]

†Drepanophycales (†Asteroxylon,†Baragwanathia,†Drepanophycus)

Lycopodiales

†Protolepidodendrales (†Leclercqia,†Minarodendron)

Selaginellales (Selaginella,including subg.Stachygynandrumand subg.Tetragonostachys)

Isoetales (Isoetes)

†Lepidodendrales (†Paralycopodites)

Evolution

[edit]
Artist's impression of aLepidodendron
External impression ofLepidodendronfrom theUpper CarboniferousofOhio
Axis (branch) fromArchaeosigillariaor related lycopod from the MiddleDevonianofWisconsin

The Lycopodiopsida are distinguished from other vascular plants by the possession of microphylls and by their sporangia, which are lateral as opposed to terminal and which open (dehisce) transversely rather than longitudinally. In some groups, the sporangia are borne on sporophylls that are clustered into strobili. Phylogenetic analysis shows the group branching off at the base of the evolution of vascular plants and they have a long evolutionary history.Fossilsare abundant worldwide, especially incoal deposits.Fossils that can be ascribed to the Lycopodiopsida first appear in theSilurianperiod, along with a number of other vascular plants. The SilurianBaragwanathia longifoliais one of the earliest identifiable species.Lycopodolicais another Silurian genus which appears to be an early member of this group.[19]The group evolved roots independently from the rest of the vascular plants.[20][21]

From theDevonianonwards, some species grew large and tree-like. Devonian fossil lycopsids fromSvalbard,growing in equatorial regions, raise the possibility that they drew down enough carbon dioxide to change the Earth's climate significantly.[22]During theCarboniferous,tree-like plants(such asLepidodendron,Sigillaria,and other extinct genera of the orderLepidodendrales) formed huge forests that dominated the landscape. Unlike modern trees, leaves grew out of the entire surface of the trunk and branches, but fell off as the plant grew, leaving only a small cluster of leaves at the top. The lycopsids had distinctive features such asLepidodendronlycophytes, which were marked with diamond-shaped scars where they once had leaves. Quillworts (order Isoetales) andSelaginellaare considered their closest extant relatives and share some unusual features with thesefossillycopods, including the development of both bark,cambiumandwood,a modified shoot system acting as roots, bipolar andsecondary growth,and an upright stance.[2][23]The remains ofLepidodendronlycopods formed many fossilcoaldeposits. InFossil Grove,Victoria Park, Glasgow, Scotland, fossilized lycophytes can be found insandstone.

The Lycopodiopsida had their maximum diversity in thePennsylvanian(Upper Carboniferous), particularly tree-likeLepidodendronandSigillariathat dominated tropical wetlands. The complex ecology of these tropical rainforestscollapsedduring the Middle Pennsylvanian due to a change in climate.[24]InEuramerica,tree-like species apparently became extinct in the Late Pennsylvanian, as a result of a transition to a much drier climate, giving way toconifers,fernsandhorsetails.InCathaysia(now South China), tree-like species survived into thePermian.Nevertheless, lycopodiopsids are rare in theLopingian(latest Permian), but regained dominance in theInduan(earliest Triassic), particularlyPleuromeia.After the worldwidePermian–Triassic extinction event,members of this group pioneered the repopulation of habitats as opportunistic plants. The heterogeneity of the terrestrial plant communities increased markedly during the Middle Triassic when plant groups like horsetails, ferns,pteridosperms,cycads,ginkgosand conifers resurfaced and diversified quickly.[25]

Microbial associations

[edit]

Lycophytes form associations with microbes such as fungi and bacteria, includingarbuscular mycorrhizalandendophyticassociations.

Arbuscular mycorrhizal associations have been characterized in all stages of the lycophyte lifecycle:mycoheterotrophicgametophyte, photosynthetic surface-dwelling gametophyte, young sporophyte, and mature sporophyte.[3]Arbuscular mycorrhizae have been found inSelaginellaspp.roots and vesicles.[26]

During the mycoheterotrophic gametophyte lifecycle stage, lycophytes gain all of their carbon from subterraneanglomaleanfungi. In other plant taxa, glomalean networks transfer carbon from neighboring plants to mycoheterotrophic gametophytes. Something similar could be occurring inHuperzia hypogeaegametophytes which associate with the same glomalean phenotypes as nearbyHuperzia hypogeaesporophytes.[3]

Fungal endophytes have been found in many species of lycophyte, however the function of these endophytes in host plant biology is not known. Endophytes of other plant taxa perform roles such as improving plant competitive fitness, conferring biotic and abiotic stress tolerance, promoting plant growth through phytohormone production or production of limiting nutrients.[27]However, some endophytic fungi in lycophytes do produce medically relevant compounds.Shiraiasp Slf14 is an endophytic fungus present inHuperzia serratathat producesHuperzine A,a biomedical compound which has been approved as a drug in China and a dietary supplement in the U.S. to treat Alzheimer's Disease.[28]This fungal endophyte can be cultivated much more easily and on a much larger scale thanH. serrataitself which could increase the availability of Huperzine A as a medicine.

Uses

[edit]

The spores of lycopods are highly flammable and so have been used infireworks.[29]Lycopodium powder,the dried spores of the common clubmoss, was used in Victorian theater to produce flame-effects. A blown cloud of spores burned rapidly and brightly, but with little heat. (It was considered safe by the standards of the time.)[citation needed]

References

[edit]
  1. ^Leonard, Janet L. (21 May 2019).Transitions Between Sexual Systems: Understanding the Mechanisms of, and Pathways Between, Dioecy, Hermaphroditism and Other Sexual Systems.Springer.ISBN978-3-319-94139-4.
  2. ^abAwasthi, D.K. (2009)."7.21".Cryptogams (Algae, Bryophyta and Pterldophyta).Meerut, India: Krishna Prakashan Media.Retrieved2019-10-21.
  3. ^abcWinther, J.L. & Friedman, W.E. (2008). "Arbuscular mycorrhizal associations in Lycopodicaceae".New Phytologist.177(3): 790–801.doi:10.1111/j.1469-8137.2007.02276.x.PMID17971070.
  4. ^Renzaglia, Karen S.; Garbary, David J. (2001)."Motile Gametes of Land Plants: Diversity, Development, and Evolution".Critical Reviews in Plant Sciences.20(2): 107–213.Bibcode:2001CRvPS..20..107R.doi:10.1080/20013591099209.
  5. ^An Overview of Green Plant Phylogeny
  6. ^Alvarez, L. (2017)."The tailored sperm cell".Journal of Plant Research.130(3): 455–464.Bibcode:2017JPlR..130..455A.doi:10.1007/s10265-017-0936-2.PMC5406480.PMID28357612.
  7. ^Greilhuber, Johann; Dolezel, Jaroslav; Wendel, Jonathan (13 November 2012).Plant Genome Diversity Volume 2: Physical Structure, Behaviour and Evolution of Plant Genomes.Springer.ISBN978-3-7091-1160-4.
  8. ^abcKenrick, Paul & Crane, Peter R. (1997a).The Origin and Early Diversification of Land Plants: A Cladistic Study.Washington, D.C.: Smithsonian Institution Press.ISBN978-1-56098-730-7.
  9. ^abcdMauseth, James D. (2014).Botany: An introduction to Plant Biology(5th ed.). Burlington, MA: Jones & Bartlett Learning.ISBN978-1-4496-6580-7.
  10. ^abcdPPG I (2016). "A community-derived classification for extant lycophytes and ferns".Journal of Systematics and Evolution.54(6): 563–603.doi:10.1111/jse.12229.S2CID39980610.
  11. ^abcdTaylor, T.N.; Taylor, E.L. & Krings, M. (2009).Paleobotany: The Biology and Evolution of Fossil Plants(2nd ed.). Amsterdam; Boston: Academic Press.ISBN978-0-12-373972-8.
  12. ^Niklas, Karl J. (2016)."Table 0.1".Plant Evolution: An Introduction to the History of Life.University of Chicago Press.ISBN978-0-226-34214-6.Retrieved2019-10-22.
  13. ^Ruggiero, Michael A.; Gordon, Dennis P.; Orrell, Thomas M.; Bailly, Nicolas; Bourgoin, Thierry; Brusca, Richard C.; Cavalier-Smith, Thomas; Guiry, Michael D. & Kirk, Paul M. (2015). "A Higher Level Classification of All Living Organisms".PLOS ONE.10(4): e0119248.Bibcode:2015PLoSO..1019248R.doi:10.1371/journal.pone.0119248.PMC4418965.PMID25923521.
  14. ^Kenrick, Paul & Crane, Peter R. (1997b)."The origin and early evolution of plants on land".Nature.389(6646): 33–39.Bibcode:1997Natur.389...33K.doi:10.1038/37918.S2CID3866183.
  15. ^Chase, Mark W. & Reveal, James L. (2009). "A phylogenetic classification of the land plants to accompany APG III".Botanical Journal of the Linnean Society.161(2): 122–127.doi:10.1111/j.1095-8339.2009.01002.x.
  16. ^Baillie, Jonathan; Hilton-Taylor, Craig & Stuart, S.N. (2004).IUCN Red List of Threatened Species 2004: A Global Species Assessment.Gland, Switzerland: IUCN—The World Conservation Union. p. 27.ISBN978-2-8317-0826-3.Retrieved2019-10-16.
  17. ^Yatsentyuk, S.P.; Valiejo-Roman, K.M.; Samigullin, T.H.; Wilkström, N.; Troitsky, A.V. (2001). "Evolution of Lycopodiaceae Inferred from Spacer Sequencing of Chloroplast rRNA Genes".Russian Journal of Genetics.37(9): 1068–1073.doi:10.1023/A:1011969716528.S2CID22187626.
  18. ^Kenrick & Crane (1997a),p. 239.
  19. ^Raymond, A.; Gensel, P. & Stein, W.E. (2006). "Phytogeography of Late Silurian macrofloras".Review of Palaeobotany and Palynology.142(3–4): 165–192.Bibcode:2006RPaPa.142..165R.doi:10.1016/j.revpalbo.2006.02.005.
  20. ^Hetherington, A.J. & Dolan, L. (2018). "Stepwise and independent origins of roots among land plants".Nature.561(7722): 235–239.Bibcode:2018Natur.561..235H.doi:10.1038/s41586-018-0445-z.PMC6175059.PMID30135586.
  21. ^Hetherington, A.J. & Dolan, L. (2019). "Rhynie chert fossils demonstrate the independent origin and gradual evolution of lycophyte roots".Current Opinion in Plant Biology.47:119–126.Bibcode:2019COPB...47..119H.doi:10.1016/j.pbi.2018.12.001.PMID30562673.S2CID56476813.
  22. ^"Tropical fossil forests unearthed in Arctic Norway".
  23. ^Stewart, Wilson N. & Rothwell, Gar W. (1993).Paleobotany and the Evolution of Plants(2nd ed.). Cambridge University Press. pp. 150–153.ISBN978-0-521-38294-6.
  24. ^Sahney, S.; Benton, M.J. & Falcon-Lang, H.J. (2010)."Rainforest collapse triggered Pennsylvanian tetrapod diversification in Euramerica".Geology.38(12): 1079–1082.Bibcode:2010Geo....38.1079S.doi:10.1130/G31182.1.
  25. ^Moisan, Philippe & Voigt, Sebastian (2013)."Lycopsids from the Madygen Lagerstätte (Middle to Late Triassic, Kyrgyzstan, Central Asia)".Review of Palaeobotany and Palynology.192:42–64.Bibcode:2013RPaPa.192...42M.doi:10.1016/j.revpalbo.2012.12.003.
  26. ^Lara-Pérez, L.A. & Valdés-Baizabal, M.D. (2015). "Mycorrhizal associations of ferns and lycopods of central Veracruz, Mexico".Symbiosis.65(2): 85–92.Bibcode:2015Symbi..65...85L.doi:10.1007/s13199-015-0320-8.S2CID8550654.
  27. ^Bacon, C.W. & Hinton, D.M. (2007). "Bacterial endophytes: the endophytic niche, its occupants, and its utility". In Gnanamanickam, S.S. (ed.).Plant-Associated Bacteria.Dorcrecht: Springer. pp. 155–194.
  28. ^Zhu, D. (2010). "A novel endophytic Huperzine A-producing fungus,Shiraisp. Slf14, isolated fromHuperzia serrata".Journal of Applied Microbiology.109(4): 1469–1478.doi:10.1111/j.1365-2672.2010.04777.x.PMID20602655.S2CID43582152.
  29. ^Cobb, B. & Foster, L.L. (1956).A Field Guide to Ferns and their related families: Northeastern and Central North America with a section on species also found in the British Isles and Western Europe.Peterson Field Guides. Boston: Houghton Mifflin. p. 215.
[edit]
Retrieved from "https://en.wikipedia.org/w/index.php?title=Lycopodiopsida&oldid=1227116909"