Bentham & Hooker's Classification. along with the merits and demerits of the systemdf

This PPT has been made to explore the plant classification in general and the classification as made by Bentham & Hooker for the classification of the flowering plants. It also offers the history of plant classification along with the merits and demerits of this aforesaid classification.

1. PLANT CLASSIFICATION
A Presentation by
Dr. N.Sannigrahi,
Associate Professor,
Department of Botany,
Nistarini College, Purulia
(W.B) India
BENTHAM & HOOKER’S
CLASSIFICATION
Tribute of Bentham & Hooker

2. CLASSIFICATION AND HISTORY
Studyofplantclassificationanditssystematicapproachesnourishesalong
historysincethetimeimmemorial.
BeforetheChristianera,theIndiansubcontinenthasbeencultivatingthis
domaininitiatedbyVrikshayurveda.
Charaka&Sushrutwerethetwopioneersinthisfieldparticularlyinthe
fieldoftraditionalknowledgeofplantsandhealthcaresystem.
Inthemiddleages,IslamicscholarsingeneralandPersianwriter,Abu
MansurinparticularwroteabookonmedicinalplantsalongwithIbnSina
during980-1037A.D.
FromtimeofTheophrastus(370-285B.C)calledfatherofBotanytookan
approachtoclassifyplants.
Broadlythreemaintypesofclassificationarefoundinthisdomain-
Artificialsystem,Naturalsystem&Phylogeneticsystemofclassification.

3. BENTHUM & HOOKER’S SYSTEM
Naturalsystemofclassificationgivesemphasisonimportantcharacters
andtheirrelatedfamilies.Amongnaturalsystemofclassification,Benthum
andHooker’ssystemofclassificationdeservesspecialattentionforits
realisticapproach.
ThesystemofclassificationofseedplantswasproposedbyBenthamand
Hooker.
It’sthemostwelldevelopednaturalclassificationsystem,itwas
publishedin3volumeworkGeneraplantarum(1862-83).
Bentham,atalentedbotanistpublishedHandbookofBritishFlora(1858)
andFloraAustraliensisin7volumes(1863-78)
Theydescribed97,205speciesofseedplantsbelongingto7,569genera
of202familiesstartingfromRanunculaceaeuptoGramineae.

4. CLASSIFICATION
Thedelimitationofgenerawasbasedonnaturalaffinitiesandwas
pre-Darwinianinconcept.•
Thesystemdividedalltheseedplantsintothreeclasses–
Dicotyledons(165families)–Gymnosperms(3families)and–
Monocotyledons(34families).
Seedwith2cotyledons
Dicotsarefurthersubdividedinto3subclasses-Polypetalae,
GamopetalaeandMonochlamydeaeaccordingtothepresenceor
absenceofpetalsandtheirfusion.
Flowerswithpentamerousortetramerous
Subclassesaredividedintoseries,cohorts(orders)andnatural
orders(families)
Monochlamydeaehasnocohorts.

5. CLASSIFICATION
POLYPETALAE:sepalsandpetalsdistinct,petalsfree(14series,
25ordersand165families)–
Thalamiflorae:flowershypogynous,stamensmany,discabsent•
6Orders:Ranales,Parietales,Polygalineae,Caryophyllineae,
GuttiferalesandMalvales,
Disciflorae:flowershypogynous,discpresentbelowtheovary
4Orders:Geraniales,Olacales,CelastralesandSapindales–
Calyciflorae:flowersperigynousorepigynous
5Orders:Rosales,Myrtales,Passiflorales,Ficoidalesand

6. CLASSIFICATION
GAMOPETALAE :Sepalsandpetalsdistinct,petalsfused–
Inferae:ovaryinferior•3orders:Rubiales,AsteralesandCampanales–
Heteromerae:Ovarysuperior,stamensinoneortwowhorls,carpelsmorethan
2•3orders:Ericales,PrimulalesandEbenales–
Bicarpellatae:Ovarysuperior,stamensinonewhorls,carpels2•4orders:
Gentianales,Polemoniales,PersonalesandLamiales
MONOCHLAMYDEAE :flowersapetalous,perianthlackingorifpresentnot
differentiatedintosepalsandpetals–Curvembryeae:embryocoiled,ovule
usually1–
Multiovulateaquaticae:aquaticplants,ovulesmany,syncarousovary
Multiovulateterrestress:terrestrialplants,ovulesmany
Microembryeae:embryominute,ovarysyncarpus,smallembryo,Surrounded
byendosperm
Daphnales:carpel1,ovule1,perianthperfect,sepaloid,perigynous
Achlamydosporae:ovaryinferior,unilocular,ovules1-3,seedwithouttesta
Unisexuales:flowersunisexual,ovarysyncarpus,perianthmuchreduced
Ordinesanomali:Relationshipuncertain

7. CLASSIFICATION
Ovules naked –3 families
MONOCOTYLEDONS: Embryo with one cotyledon, stem with
closed vascular bundle, parallel venation, trimerous flowers with 7
series
Microspermae:ovaryinferior,seedsminute–
Epigynae:ovaryinferior,seedslarge–
Coronarieae:ovarysuperior,carpelsunited,perianthcolored–
Calycinae:ovarysuperior,carpelsunited,perianthgreen–
Nudiflorae:ovarysuperior,perianthabsent–
Apocarpae:ovarysuperior,carpelsmorethan1,free–
Glumaceae:ovarysuperior,perianthreduced,flowersenclosedin
glumes

8. OUTLINE OF CLASSIFICATION

9. MERITS OF CLASSIFICATION
Eachplanthasbeendescribedeitherfromtheactualspecimenorpreserved
herbariumsheetssothatthedescriptionsaredetailedaswellasquiteaccurate.
Thesystemishighlypracticalandisusefultostudentsofsystematicbotanyfor
easyidentificationofspecies.
Thefloradescribesgeographicaldistributionofspeciesandgenera.
Thegenericdescriptionsarecomplete,accurateandbasedondirectobservation
withhighdegreeofpracticalattainments.
Largergenerahavebeendividedintosubgenera,eachwithspecificnumberof
species.
ThreeseriesThalamiflorae,DiscifloraeandCalycifloraeshowgradual
evolutioaryadvancementfromhypogynytoepigyny.
DicotsbeginwiththeorderRanaleswhicharenowuniversallyconsideredasto
bethemostprimitiveangiosperms.
Placingofmonocotsafterthedicotisagainanaturaloneandaccordingto
evolutionarytrends.
Theplacingofseriesdiscifloraeinbetweenthalamifloraeandcalycifloraeis
quitenatural.
Theplacingofgamopetalaeafterpolypetalaeisjustifiedsinceunionofpetalsis
consideredtobeanadvancedfeatureoverthefreecondition

10. DEMERITS
Keepinggymnospermsinbetweendicotsandmonocotsisanomalous.
Subclassmonochlamydeaeisquiteartificial.
Placingofmonochlamydeaeaftergamopetalaedoesnotseemtobenatural.
Someofthecloselyrelatedspeciesareplaceddistantlywhiledistantspeciesare
placedclosetoeachother.
Certainfamiliesofmonochlamydeaearecloselyrelatedtofamiliesin
Polypetalae,e.g.ChenopodiaceaeandCaryophyllaceae
Advancedfamilies,suchasOrchiadaceaehavebeenconsideredprimitiveinthis
systembyplacingtheminthebeginning.PlacingofOrchiadaceaeinthe
beginningofmonocotyledonsisunnaturalasitisoneofthemostadvanced
familiesofmonocots.
Similarly,Compositae(Asteraceae)hasbeenplacednearthebeginningof
gamopetalaewhichisquiteunnatural.
LiliaceaeandAmaryllidaceaewerekeptapartmerelyonthebasisofcharacters
ofovarythoughtheyareverycloselyrelated.
TherewerenophylogeneticconsiderationasitwaspublishedbeforeDarwinian
conceptofevolution.

11. INNATURALSCIENCE, THEPRINCIPLESOFTRUTHOUGHT
TOBECONFIRMED BYOBSERVATION”-LINNAEUS
REFERENCES:
Plant taxonomy-O.P. Sharma
Text Book of plant Systematics-C.R. Mohanty
Advanced plant taxonomy-A.K. Mondal
Taxonomy of Angiosperms-P.C. Vasistha
Plant taxonomy-Theory & Practice-G. Singh
Google for images
Different WebPages for study materials
Disclaimer:
This PPT has been developed to enrich online study resources for
academic fraternity without any financial interest.

12. THANK YOU FOR YOUR PATIENCE