Takhtajan System of Plant Classification.pdf

Phylogenetic system of plant classification is an important domain in plant taxonomy. The evolutionary history and its role in the development of biodiversity is an interesting episode for all biologists. Takhtajan's system of plant classification presentation offers a bird's eye view of this approach and highlights the primitiveness versus advancement in plant characteristics.

1. Presented by
Dr. N. Sannigrahi,
Associate Professor,
Department of Botany,
Nistarini College, Purulia,
D.B. Road, Purulia, (W.B.) 723101, India

3. Theoutlookoftaxonomywaschangedwiththepublicationof“Originof
Species”byDarwinin1859.Afterthat,therewasmoreandmoreinterest
inclassifyingorganismswiththeincorporationoftheevolutionary
relationshipsoftheevolutionaryhistory,includingthegeneticrelationships
oftheorganisms.Theevolutionaryhistoryofagroupofgeneticallyrelated
organismsiscalledaphylogeny.Itincludesancestorspeciesand
descendentspecies.Aphylogenyisusuallyrepresentedbyatreediagram
calledaphylogenetictree.
Thevariousbotanistswhoadoptedphylogeneticsystemsare:1.A.W.
Eichler:HemodifiedBenthamandHooker’ssystemofclassificationby
placinggymnospermsinthebeginning.Heisalsocalledasthepioneerin
phylogeneticsystemofclassification.
2.AdolphEnglerandKarlA.E.Prantl,thetwoGermanbotanistspublished
atwentythreevolumeworkin“DieNaturlichenpflanzenfamilien”(1887
1915).ItwasaGermanworkwhichwaslatertranslatedinEnglish.

5. Hewasoneofthemostinfluentialbotanistsandsystematistsof20th
century.
Takhtajan,reputedpalaeobotanistofKomarovBotanicalInstituteof
Leningrad,(USSR)nowRussiahaveagreatcontributioninangiosperm
phylogenyandplanttaxonomy.
In1942,hedevelopedaclassificationschemeforfloweringplants.After
12yearsi.e.in1954,theactualsystemofclassificationwaspublishedin
his“DieEvolutionDerAngiosperm”i.e.TheOriginofAngiospermous
plantsinRussianlanguage.Theclassificationwaspublishedin“Flowering
plants:OriginandDispersal”(1969)inEnglish.Lateronin1980,anew
revisionofhissystemwaspublished.
Takhtajan’ssystemofclassificationisbasicallyofBessey-Halliertradition
Whichconsideredallevidencesfromdifferentfieldsincluding
morphological,anatomical,embryological,cytological,palynological,
paleobotanical,chemicalandultrastructuralevidenceswhileclassifying
Angiosperms..

6. Heconsideredangiospermsasmonophyleticinoriginandarosefromsome
ancientgroupsofGymnosperms.
Themonocotyledonsare,consideredtohavebeenderivedfromprimitive
Dicotyledons.
HeclassifiedangiospermsasDivision:Magnoliophytaandsubdivided
themintotheDicotyledons(Class:Magnoliopsida)andmonocotyledons
(Class:Liliopsida).
MagnoliopsidaisconsideredprimitiveandLiliopsidatohavebeenderived
fromMagnolialesunderMagnoliopsida.
Magnoliopsidacontains11subclassesandLiliopsidacontains6subclasses,
Thehierarchicalorganizationis:Division→Class→subclass→Super-
order→Orders→Families

7. Takhtajan’ssystemofclassificationbasedon67phyleticprinciples.
Someofthecriteriausedbyhimtoevaluatetherelativedegreeof
advancementoffloweringplantsasfollows:
Woodyplantsaremoreprimitivethanherbaceousplants,
Deciduouswoodyplantsareconsideredevolvedfromevergreenplants,
Xylemfibersevolvedfromtracheidstolibriformfibers,throughfiber
tracheids,
Trilacunarorpentalacunarnodesaremoreprimitivetouniulacunarnode,
Alternateleafarrangementismoreprimitivewhileparallelevolutionis
mostadvanced,
Stomatawithsubsdiarycellsareprimitivethanthoselackingsubsidiary
cells,
Cymoseinflorescenceismoreprimitivethanracemose,
Flowerswithanindefiniteorvariablenumbersoffloralpartsareprimitive
thanlimitednumberoffloralleaves.

8. Pollenswithunsculpteredexineisprimitivetosculpturedpollen,
Entomophiliesismoreprimitivethanothertypesofpollinationasper
pollendisseminationisconcerned,
Apocarpousgynoeciumisprimitiveoversyncarpousgynoecium,
Bitegmicovulesareprimitivethanunitegmicovules,whileanatropous
ovuleismoreprimitive,
8-nucleatedPolygonumtypeoffemalegametophyteismostprimitive,
MespgamicandChalazogamicconditionshaveevolvedfromporogamic
condition,
Manyseededfollicleismostprimitivethanmostotherfruittypes,

9. Characters Primitive Advance
Growth Habit Woody habit, Smallwoody,
Evergreen ,
Herbaceous, large trees with
numerous slender branches.
Leaves Simple, Reticulate venation with
alternate arrangement,
Compoundwith parallel venation
and opposite leaves,
Stomata Misogynous type with subsdiary
cells,
Parigynous without subsdiary
cells,
Nodal
structure
Tri to pentalacunar, Unilacular node,
Inflorescence Cymose, Racemose,
Floral
structure
Indefinite with variable number
of floral parts,
Fixed number of floral parts with
cyclic pattern,
Pollen grains Exine devoid of external
sculpturing,
Sculpturing of various types,
tricolpate,
Gynoecium Apocarpous, Syncarpous,
Ovules Anatropous Other types

10. Characters Primitive Advance
Pollination Entomophilies Anemophily
Gametophyte
and
fertilization
Monosporic and Polygonum type,Endosperm is reduced or wanting
and the embryo is large and well
differentiated,
Fruits Many seeded follicular fruit
develop from multicarpellary
apocarpousgynoecium
Coenocarpous fruits,

11. Armen Takhtajan (1997) revised the classification
Diversity and Classification of Flowering Plants” treated flowering plants
–Magnoliophyta into two classes-Magnoliopsida a (dicots) and Liliopsida
( Monocot)
Magnoliopsida divided into 11 subclasses, 56 super-orders, 225 orders
Liliopsida into 6 classes, 16 super-orders and 58 orders
The class Magnoliopsida starts with the family Degeneriaceae and ends in
Hippuriudaceae,
Class Liliopsida starts with the family Tofieldiaceae and ends in
Typhaceae.

12. SUB-CLASS SUPERORDER ORDER
Magoniidae Magnoliane –
Balanophoranae (6)
Magnoliales –
Balanophorales (18 )
Nymphaeidae Nymphaenae,
Ceratophyllanae
Hydropeltidales,
Nymphaales
Ceratophyllales (3)
Ranunculidae Ranunculanae Lardizales to Papavarles(9)
Caryophyllidae Caryophyllanae to
Plumbaginanae (4)
Caryophyllales to
Plumbaginales (4)
Hamameliudidae Trochodendranaeto
Juglandanae (9)
Trochodendrales to
Juglandales (17)
Dilleniidae Dillenianae to
Euphorbianae (10)
Dilleniales to Thymelaeales
(40)
Rosidae Saxifraganaeto Vitanae
(13)
Cunoniales to Vitales (45)
Cornidae Cornanae to Dipsacanae (3)Hydrangeales to Dipsacales
(17)

13. SUB-CLASS SUPERORDER ORDER
AsteridaeCampanulanae and Asteranae (2)Campanulales to Asterales (6)
Lamiidae Gentianae to Lamianae (5)Gentianales to Hippuridales (15)
LILIOPSIA
(CLASS)
MONOCOTS
Liliidae Lilianae ,Dioscoreanae (2)Melanthialesto Taccales (18)
Commelinidae Bromelianae to Poanae (7)Bomeliales to Poales (21)
Arecidae Arecanae (1) Arecales (1)
Allismatidae Alismatane(1) Butomales to Zosterales(11)
Triurididae Triuridanae (1) Petrosaviales, Triuridales (2)
Aridae Aranaeto Typhanae (4) Arales to Typhales (4)

14. TheTakhtajansystemofclassificationismorephylogeneticthanthatof
earliersystemasproposedbythedifferenttaxonomistsbeforeorhis
contemporary.
Inageneralagreement,thesystemofclassificationiswiththemajor
contemporarysystemofclassificationlikeCronquist,Dahlgren,Thorne
andothers.Bothphylogeneticandpheneticinformationwereadoptedfor
thedelimitationordersandfamilies.
DuetotheabolitionofseveralnaturalgroupslikePolypetalae,
Gamopetalae.Lignosae,Herbaceaeandmanynaturaltaxacameclose
together.Forexample,Lamiaceae(earlierplacedunderHerbaceae)and
Verbenaceae(PlacedunderLignosae)arebroughttogetherundertheorder
Lamiales.
TheICBNhasbeenwidelyusedinthecaseofnomenclatureofplantseven
atthelevelofdivision.
ThetreatmentofMagnoliidaeasaprimitivegroupandtheplacementof
DicotyledonsbeforeMonocotyledonsareinagreementwithother
contemporarygroups.

15. Thederivationofmonocotsfromtheextinctterrestrialhypotheticalgroup
ofMagnoliidaeisfoundtobelogical.
DEMERITS
TheTakhtajansystemofclassificationismoreincladisticsinformationin
comparisonofpheneticinformation.
Thesystemofclassificationprovidestheinformationuptothefamily
level,thusitislesssuitableforidentificationandforadoptioninHerbaria.
Inaddition.Nokeyhasbeenprovidedforidentificationoftaxa.
Takhtajanrecognizedangiospermsasdivisionwhichactuallydeservea
classrankthatofthesystemsofDahlgren(1983)andThorne(2003).
Numerousmonotypicfamilieshavebeencreatedin1997duetothefurther
splittingandincreaseinthenumberoffamiliesto592(533in1987),
resultingintoaverynarrowcircumscription.

16. Takhtajansuggestedthatsmallerfamiliesaremorenaturalandthishas
openedthewindowofcriticism.
AlthoughthefamiliesWinteraceaeandCanellaceaeshowedtheir99-100%
(almost)relationshipbymultigeneanalysis,Takhtajanplacedthesetwo
familiesintwoseparateorders.
ThemainobjectiontoTakhtajan’ssysteminhisderivationof
MonocotyledonsfromthestocksancestraltotheNymphaeales.
Theextremelynarroweddefinedtaxainthissystemhasresultedinthe
unwarrantedsplittingofrelatedgroups.
Lastbutnotleast,thesystemdeservesappreciationdespitethe
shortcomingsinthesystemandthishasexpeditedthethoughtandresearch
appetiteinthefieldofmoderntaxonomy.

18. References:
Google for different images incorporated into this PPT,
Different WebPages for reference and content,
Advanced Plant Taxonomy-A.K. Mondal,
A Textbook of Botany-Bhattacharya, Hait, Ghosh,
Plant Taxonomy-O.P. Sharma,
Text Book of Plant Systematics -C. Maity.
Disclaimer:
Thispresentationhasbeenmadeanddesignedasthefreeopensourceof
studymaterialsintendedfortheacademicfraternity.Thepresenterdoesnot
claimanykindoffinancialinterestforthiswork.Itiscompletelyfreefor
use.Theauthorisgratefultousetheresourcesfromthedifferentauthors
andGoogleforthisendeavor.