04 Classification

7/27/2019 04 Classification

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Classification of Classification of

AngiospermsAngiosperms

Classification of AngiospermsClassification of Angiosperms

•• important non-Western systemsimportant non-Western systems

•• Parashara (India) 2000 BCParashara (India) 2000 BC

•• ChineseChinese

•• AztecsAztecs

•• EgyptiansEgyptians

•• folk systematics (ethnotaxonomy)folk systematics (ethnotaxonomy) —— scientific?scientific?

•• classification is the 3rd goal of systematicsclassification is the 3rd goal of systematics

•• ancient search forancient search for ““naturalnatural”” system of classificationsystem of classification

Folk ClassificationsFolk Classifications•• 5-6 categories5-6 categories

•• arranged hierarchicallyarranged hierarchically

•• unique beginnerunique beginner = kingdom= kingdom

•• plant, animalplant, animal



•• unique beginner = kingdomunique beginner = kingdom

•• life formslife forms (tree, vine, grass)(tree, vine, grass)

Unique form: cactus in Tzeltal (Mayan)Unique form: cactus in Tzeltal (Mayan)




•• arranged hierarchicallyarranged hierarchically•• unique beginner = kingdomunique beginner = kingdom

•• life formslife forms (tree, vine, grass)(tree, vine, grass)

Unique form : strangler - Aguaruna (Peru)Unique form : strangler - Aguaruna (Peru)


•• arranged hierarchicallyarranged hierarchically•• unique beginner = kingdomunique beginner = kingdom

•• life forms (tree, vine, grass)life forms (tree, vine, grass)

•• genericgeneric

•• 500 +/- in most systems500 +/- in most systems

•• most important levelmost important level

•• similar to Theophrastus,similar to Theophrastus,

Linnaeus, etc.Linnaeus, etc.



•• unique beginner = kingdomunique beginner = kingdom

•• life forms (tree, vine, grass)life forms (tree, vine, grass)

•• genericgeneric

•• 500 +/- in most systems500 +/- in most systems•• most important levelmost important level

•• similar to Theophrastus,similar to Theophrastus,

Linnaeus, etc.Linnaeus, etc.

•• specific/varietalspecific/varietal

•• 1-3 at most1-3 at most

•• more in special plantsmore in special plants

Folk ClassificationsFolk Classifications

Are these indigenous, innateAre these indigenous, innate

classifications non-scientific?classifications non-scientific?

62% of folk genera match62% of folk genera match

““scientificscientific”” species!species!






Tzeltal classification recognizesTzeltal classification recognizes one folkone folk

genus for 2+ scientific speciesgenus for 2+ scientific species about 20%about 20%

Lantana




Tzeltal classification recognizesTzeltal classification recognizes one folkone folk

genus for 2+ scientific generagenus for 2+ scientific genera about 14%about 14%

Pinus Abies




Tzeltal classification recognizesTzeltal classification recognizes 2+ folk2+ folk

species for 1 scientific speciesspecies for 1 scientific species about 3%about 3%

pepperspeppers




Tzeltal classification recognizesTzeltal classification recognizes 2+ folk2+ folk

species for 1 scientific speciesspecies for 1 scientific species about 3%about 3%

Over-differentiation in 4 ethnotaxonomiesOver-differentiation in 4 ethnotaxonomies

involveinvolve importantimportant taxataxa

pepperspeppers




Further evidence that all humans perceiveFurther evidence that all humans perceive

biodiversity and classify in similar waysbiodiversity and classify in similar ways

HanunHanunóóoo

1. Level of 1. Level of polytypypolytypy in genera (monotypicin genera (monotypic

= 1 sp. per genus, etc.) is similar= 1 sp. per genus, etc.) is similar

worldwideworldwide

# species / genus# species / genus

#

g e n e r a

#

g e n e r a


Further evidence that all humans perceiveFurther evidence that all humans perceive

biodiversity and classify in similar waysbiodiversity and classify in similar ways

2. Level of 2. Level of polytypypolytypy of folk classificationof folk classification

andand ““scientificscientific”” flora is identical!flora is identical!

HanunHanunóóoo

# species / genus# species / genus

#

g e n e r a

#

g e n e r a

Systems of ClassificationsSystems of Classifications

Examine three main systems of Examine three main systems of

classifications and how theyclassifications and how they ““evolvedevolved”” in thein the

context of western civilizationcontext of western civilization

Artificial ClassificationsArtificial Classifications

Theophrastus (372-287 BC) took theTheophrastus (372-287 BC) took the

philosophical ideas of Plato and Aristotlephilosophical ideas of Plato and Aristotle

and applied them to taxonomyand applied them to taxonomy

‘‘essentialismessentialism’’

““a genus is any group of a genus is any group of

species that may bespecies that may be

logically and exhaustivelylogically and exhaustively

distinguished on the basisdistinguished on the basis

of one or a very fewof one or a very few

essential propertiesessential properties””




Theophrastus (372-287 BC) took theTheophrastus (372-287 BC) took the

philosophical ideas of Plato and Aristotlephilosophical ideas of Plato and Aristotleand applied them to taxonomyand applied them to taxonomy

herbherb subshrubsubshrub shrubshrub treetree

HabitHabit as an essential characteras an essential character

De Historia Plantarum De Historia Plantarum

Theophrastus saw aTheophrastus saw a linear gradationlinear gradation whenwhen

essences are used to arrange organismsessences are used to arrange organisms

‘‘essentialismessentialism’’


This linear gradation concept is theThis linear gradation concept is the

AristotleanAristotlean Scalae NaturaeScalae Naturae oror GreatGreat

Chain of BeingChain of Being oror Ladder of LifeLadder of Life

Scalae Naturae

Concept of Concept of ladder of lifeladder of life still aroundstill around

today and causes much of thetoday and causes much of the

controversy surrounding evolutioncontroversy surrounding evolution

Unidirectional progressionUnidirectional progression andand rankrank onon

ladder leads to (false) ideas of ladder leads to (false) ideas of

relationships -relationships - fish fish more closelymore closely

related torelated to molluscsmolluscs than fish are tothan fish are to

humanshumans


Evolution does not advocate thisEvolution does not advocate this

““ladderladder”” of life, but rather advocates aof life, but rather advocates a

““branching treebranching tree””

Evolution asserts (testable!) that fishEvolution asserts (testable!) that fish

are more closely related to humansare more closely related to humansbecause they have a more recentbecause they have a more recent

common ancestor Acommon ancestor A than the commonthan the common

ancestorancestor BB with molluscswith molluscs

A

B


. . . back to Theophrastus and his. . . back to Theophrastus and his

classification of plantsclassification of plants

herbherb subshrubsubshrub shrubshrub treetree

•• logical but rigid system of classificationlogical but rigid system of classification

—— a prioria priori choice of characterschoice of characters

•• clearlyclearly artificialartificial as conifers areas conifers are

placed with some (woody)placed with some (woody)angiosperms and some (woody) fernsangiosperms and some (woody) ferns

white pinewhite pine

red oakred oak

tree ferntree fern




HerbalistsHerbalists : a second group using artificial: a second group using artificial

systems of classificationsystems of classification

•• association of plant taxonomy withassociation of plant taxonomy with

medicine goes back to Dioscorides (ADmedicine goes back to Dioscorides (AD

60)60)

•• here prescribinghere prescribing ““mandrakemandrake”” in thein the

nightshade familynightshade family

•• family Dioscoreaceaefamily Dioscoreaceae – – yam familyyam family – –

named after this doctornamed after this doctor

Dioscorea villosa Dioscorea villosa --

wild yamwild yam

Source of edible yam; sources of Source of edible yam; sources of

steroids, cortisones, first oralsteroids, cortisones, first oral

contraceptives (diosgenin,contraceptives (diosgenin,

progesterone)progesterone)

Dioscorea sp. Dioscorea sp.







•• association of plant taxonomy withassociation of plant taxonomy with

medicine goes back to Dioscorides (ADmedicine goes back to Dioscorides (AD60)60)

•• publishedpublished De Materia Medica De Materia Medica

in which medicinal plants werein which medicinal plants were

listed by medicinal propertieslisted by medicinal properties




•• after Dark Ages, renewed interest inafter Dark Ages, renewed interest in

medicinal value of herbs due to greatmedicinal value of herbs due to greatplagues of 15-16plagues of 15-16thth centuriescenturies

•• invention of Europeaninvention of European

printing press in 15printing press in 15thth centurycentury

facilitated printing of facilitated printing of

information intoinformation into ‘‘herbalsherbals’’






•• little emphasis placed on system of little emphasis placed on system of

classification of the plantsclassification of the plants —— alphabeticalalphabetical

or medicinal propertyor medicinal property

•• less than 1000 species of less than 1000 species of

plants were known; no need forplants were known; no need for

intricate classification systemintricate classification system

in thein the herbalsherbals




•• herbals often lavishly illustratedherbals often lavishly illustrated

•• herbalists referred to as theherbalists referred to as the

‘‘German Fathers of BotanyGerman Fathers of Botany’’ De Historium Stirpium De Historium S tirpium - Fuchs- Fuchs

1580 - 1800: Pivotal Period1580 - 1800: Pivotal Period

Artificial or Natural Systems?Artificial or Natural Systems?

•• world-wide trade and explorationworld-wide trade and exploration ——

manymany new plant speciesnew plant species were seen bywere seen by

European taxonomistsEuropean taxonomists Linnaeus & studentsLinnaeus & students’’ travelstravels





European taxonomistsEuropean taxonomists Sir Joseph Banks (1768-1771)Sir Joseph Banks (1768-1771)







European taxonomistsEuropean taxonomists Sir Joseph Banks (1768-1771)Sir Joseph Banks (1768-1771)

•• moremore formal system of formal system of

classificationclassification waswas

necessarynecessary

•• suites of instrinsicsuites of instrinsic

characterscharacters of plants neededof plants needed

to be usedto be used



Andrea Caesalpino (1519-1603) - Italian doctorAndrea Caesalpino (1519-1603) - Italian doctor

•• struggled with questionstruggled with question how to form ahow to form a

moremore ‘‘naturalnatural’’ classificationclassification

•• private collection of 768 plantsprivate collection of 768 plants

arranged in 266 sheets in 3 volumesarranged in 266 sheets in 3 volumes

•• arranged by reproductive featuresarranged by reproductive features

of the plants -of the plants - flowers and fruitsflowers and fruits

•• firstfirst natural systemnatural system, first, first

herbarium, first botanical gardenherbarium, first botanical garden



Andrea Caesalpino (1519-1603) - Italian doctorAndrea Caesalpino (1519-1603) - Italian doctor

•• firstfirst natural systemnatural system, first, first

herbarium, first botanical gardenherbarium, first botanical garden

Pisa, ItalyPisa, Italy



John Ray (1628-1705) - English blacksmithJohn Ray (1628-1705) - English blacksmith

•• argued thatargued that all parts of the plantall parts of the plant

should be usedshould be used in classificationin classification•• classified 18,000 species inclassified 18,000 species in

Methodus Plantarum Methodus Plantarum (1703)(1703)

first byfirst by fruitfruit types andtypes and

subdivided bysubdivided by flowerflower andand leaf leaf

featuresfeatures





John Ray (1628-1705) - English blacksmithJohn Ray (1628-1705) - English blacksmith

•• first recognized distinction betweenfirst recognized distinction between dicotsdicots

andand monocotsmonocots

2525 ‘‘classesclasses’’ of dicotsof dicots

44 ‘‘classesclasses’’ of monocotsof monocots

== ordersorders todaytoday



Pierre Magnol (1638-1715) - French botanistPierre Magnol (1638-1715) - French botanist

•• considered Rayconsidered Ray’’s system of 29s system of 29 ‘‘classesclasses’’

too cumbersometoo cumbersome

•• classified 76classified 76 ‘‘familiesfamilies’’ —— first to recognizefirst to recognize

familyfamily levellevel ((MagnoliaceaeMagnoliaceae honored after him)honored after him)



Carolus Linnaeus (1707-1778) - SwedishCarolus Linnaeus (1707-1778) - Swedish

taxonomisttaxonomist

•• work of Caesalpino, Ray, andwork of Caesalpino, Ray, and

Magnol in producing aMagnol in producing a workableworkable

classification systemclassification system culminated inculminated in

LinnaeusLinnaeus’’ Sexual SystemSexual System

•• however, this classification systemhowever, this classification system

was awas a backward stepbackward step in the progressin the progress

towardstowards natural systemsnatural systems

Linnaeus - Sexual SystemLinnaeus - Sexual System

What did he do?What did he do?

•• $125 grant in 1732 funded 5 month$125 grant in 1732 funded 5 month

floristic inventory of Laplandfloristic inventory of Lapland

•• priceless collection was thepriceless collection was theimpetus for his treatment of theimpetus for his treatment of the

world-wide floraworld-wide flora




What did he do?What did he do?

•• greatest achievement -greatest achievement - SpeciesSpecies

PlantarumPlantarum in 1753 arranged asin 1753 arranged as

Systema SexualeSystema Sexuale

•• classification based onclassification based on

reproductive features likereproductive features like

Caesalpino, but selective andCaesalpino, but selective and

features chosenfeatures chosen a prioria priori simplysimply

onon workabilityworkability


Take a closer look insideTake a closer look inside SpeciesSpecies

PlantarumPlantarum

•• prime divisions based onprime divisions based on number of number of

stamensstamens

•• secondary divisions based onsecondary divisions based on

number of pistilsnumber of pistils

•• was Linnaeus a sexist?was Linnaeus a sexist?

•• not here! number of stamens morenot here! number of stamens more

variable than of pistils -variable than of pistils - essential for aessential for a

mechanical, workable systemmechanical, workable system


How does it work?How does it work? OenotheraOenothera

biennisbiennis or evening primroseor evening primrose

•• OenotheraOenothera has 1 pistil (but 4 fusedhas 1 pistil (but 4 fused

carpels) - placed incarpels) - placed in Monogynia Monogynia (2(2nd nd level)level)

•• OenotheraOenothera has 8 stamens - placed inhas 8 stamens - placed in

OctandriaOctandria (1(1st st level)level)


Note thatNote that OenotheraOenothera is placed with otheris placed with other

genera of the family Onagraceaegenera of the family Onagraceae

Gaura Epilobum




Linnaeus and followers DID realize thatLinnaeus and followers DID realize that

the system would have issuesthe system would have issues

•• cacti and cherries have little overallcacti and cherries have little overall

similarity to each othersimilarity to each other

OpuntiaOpuntia

PrunusPrunus

•• but both have many stamens and a singlebut both have many stamens and a single

pistilpistil —— placed inplaced in Polyandria / MonogyniaPolyandria / Monogynia

•• Linnaeus more concerned withLinnaeus more concerned with mechanics:mechanics:

usable, predictable, expandable, immutableusable, predictable, expandable, immutable

•• Sexual System artificial, and thus backwardSexual System artificial, and thus backward

step towardsstep towards ‘‘naturalnatural”” classificationsclassifications

•• taxonomists reconsideredtaxonomists reconsidered

purposes of classification;purposes of classification;

revisited olderrevisited older ‘‘naturalnatural’’ ideasideas

Natural ClassificationsNatural Classifications

Period of Natural Systems: 1760 - 1880Period of Natural Systems: 1760 - 1880

•• late 18th century sawlate 18th century saw

accumulation of botanicalaccumulation of botanical

collectionscollections

•• Linnaeus had provided popularLinnaeus had provided popular

and efficient cataloguing schemeand efficient cataloguing scheme

but unrelated plants were oftenbut unrelated plants were often

groupedgrouped



•• the number and diversity of the number and diversity of

tropical plants in Senegaltropical plants in Senegal

influencedinfluenced Michel AdansonMichel Adanson

•• grouped plants by affinitiesgrouped plants by affinities

observed among multipleobserved among multiple

relationships of characteristicsrelationships of characteristics

•• published his classification inpublished his classification in

Familles des PlantesFamilles des Plantes in 1763in 1763

David BaumDavid Baum is the world expert onis the world expert on

the evolution and pollinationthe evolution and pollination

biology of the baobabs - mainlybiology of the baobabs - mainly

found in Madagascar - named afterfound in Madagascar - named after

Michel Adanson.Michel Adanson.•• Adansonia Adansonia - the baobabs- the baobabs

What is one of the twoWhat is one of the two

main pollinators that Davidmain pollinators that David

photographed visitingphotographed visiting

flowers of the baobabs?flowers of the baobabs?





•• de Jussieude Jussieu family of Parisfamily of Paris

produced the most completeproduced the most complete

‘‘naturalnatural’’ classificationclassification

•• their natural system came fromtheir natural system came from

the practice of the practice of ‘‘taxonomictaxonomic gardensgardens’’

Antoine-Laurent de JussieuAntoine-Laurent de Jussieu



•• private and public gardens were thenprivate and public gardens were then

arranged according to the Linnaeanarranged according to the Linnaean

Sexual SystemSexual System of classificationof classification

Linnaean Gardens in Uppsala, SwedenLinnaean Gardens in Uppsala, Sweden



•• Bernard de Jussieu experimented byBernard de Jussieu experimented by

replanting in the Trianon Garden onreplanting in the Trianon Garden on

Versailles Palace grounds so that those mostVersailles Palace grounds so that those most

““similarsimilar”” looking on the basis of manylooking on the basis of manyfeatures would be in proximityfeatures would be in proximity

Bernard -

uncle

Antoine -

nephew



•• Antoine Laurent de Jussieu publishedAntoine Laurent de Jussieu published

Genera PlantarumGenera Plantarum in 1789 based on the dein 1789 based on the de

Jussieu familyJussieu family’’s new, mores new, more naturalnatural

classification systemclassification system - and today reflected- and today reflectedin the plantings at the Trianon Gardensin the plantings at the Trianon Gardens



Phylogenetic ClassificationsPhylogenetic Classifications

Phylogenetic systems date to 1859 and publication of Phylogenetic systems date to 1859 and publication of

Origin of SpeciesOrigin of Species by Charles Darwinby Charles Darwin


Phylogenetic systems date to 1859 and publication of Phylogenetic systems date to 1859 and publication of

Origin of SpeciesOrigin of Species by Charles Darwinby Charles Darwin

•• ‘‘NaturalNatural’’ had meant different things tohad meant different things to

different peopledifferent people

•• to Linnaeus and othersto Linnaeus and others ‘‘naturalnatural’’ referredreferred

to the ordered structure of the universe andto the ordered structure of the universe and

biota as ordained by God -biota as ordained by God - specific orspecific or

special creationspecial creation

•• to others this grouping of taxa into largerto others this grouping of taxa into larger

groupsgroups implied relationships based onimplied relationships based on

genealogygenealogy - with or without a God- with or without a God


Phylogenetic systems to Darwin must includePhylogenetic systems to Darwin must include

genealogy + amount of change (or similarity)genealogy + amount of change (or similarity)

•• ““classification must be genealogicalclassification must be genealogical””

•• ““genealogy alone does not givegenealogy alone does not giveclassificationclassification””

•• ““descent with modificationdescent with modification”” : or: or

genealogy plus change = evolutiongenealogy plus change = evolution


Phylogenetic systems represented byPhylogenetic systems represented by

thethe ““treetree”” metaphormetaphor

•• Darwin argued thatDarwin argued that ““commoncommon

ancestryancestry”” is a factis a fact —— and outcomeand outcome

is a phylogeneticis a phylogenetic ‘‘treetree’’

•• less than a decade later Ernstless than a decade later Ernst

Haeckel published the firstHaeckel published the first tree of tree of

lifelife

•• all classification systems sinceall classification systems since

have beenhave been phylogeneticphylogenetic




Bentham & Hooker at Kew Royal Botanic Gardens firstBentham & Hooker at Kew Royal Botanic Gardens first

systematists to wrestle with phylogenetic classificationssystematists to wrestle with phylogenetic classifications

George BenthamGeorge Bentham

1800-18841800-1884Joseph HookerJoseph Hooker

1817-19111817-1911

•• provided Darwin withprovided Darwin with

much of his botanicalmuch of his botanical

evidence for evolutionevidence for evolution

•• rudimentaryrudimentary

phylogenetic systemphylogenetic system

quickly over-shadowed byquickly over-shadowed by

two younger Germanstwo younger Germans


Engler and Prantl produced the monumentalEngler and Prantl produced the monumental Die Die

Naturlichen Pflanzenfamilien Naturlichen Pflanzenfamilien between 1887-1915between 1887-1915

Adolph EnglerAdolph Engler

1844-19301844-1930Karl PrantlKarl Prantl

1849-18931849-1893


Engler and Prantl produced the monumentalEngler and Prantl produced the monumental Die Die

Naturlichen Pflanzenfamilien Naturlichen Pflanzenfamilien between 1887-1915between 1887-1915

Adolph EnglerAdolph Engler

1844-19301844-1930Karl PrantlKarl Prantl

1849-18931849-1893

•• original classificationoriginal classification

waswas ‘‘naturalnatural’’ and basedand based

on many characterson many characters

•• by 1915 their systemby 1915 their system

had ahad a phylogeneticphylogenetic flavorflavor

withwith simple plantssimple plants listedlisted

first andfirst and progressing toprogressing to

moremore complex plantscomplex plants


Engler - Prantl classification system became the standardEngler - Prantl classification system became the standard

to arrange herbaria and floras by early 20to arrange herbaria and floras by early 20 thth centurycentury

•• stressed thatstressed that ““simplesimple”” flowersflowers

- that is with few or no parts -- that is with few or no parts -

werewere ““primitiveprimitive””

•• e.g.,e.g., ““AmentiferaeAmentiferae”” - a group- a group

with reduced flowers werewith reduced flowers were

considered primitiveconsidered primitive

•• their system can be calledtheir system can be called

““simple = primitivesimple = primitive”” oror ““SalixSalix

= primitive= primitive””

SalixSalix - willow- willow




Charles Bessey revolutionized the classification of Charles Bessey revolutionized the classification of

angiosperms by his ideas onangiosperms by his ideas on primitive vs. advanced charactersprimitive vs. advanced characters

•• hypothesized thehypothesized the primitiveprimitive

vs. advanced statevs. advanced state of manyof many

characters of plants -characters of plants - seesee

handout handout

•• BesseyBessey’’ss ‘‘dictadicta’’ or rules wereor rules were

the basis of his phylogeneticthe basis of his phylogenetic

classification schemeclassification scheme

•• formed the basis for allformed the basis for all

subsequent modern systemssubsequent modern systems

Charles Bessey (1848-1915)Charles Bessey (1848-1915)

at University of Nebraskaat University of Nebraska


What wereWhat were BesseyBessey’’ss main dicta or rules?main dicta or rules?

epigynoushypogynous4. Ovary position4. Ovary position

zygomorphyactinomorphy3. Floral symmetry3. Floral symmetry

parts fusedparts separate2. Floral fusion2. Floral fusion

loss of parts, few innumber

all present, many innumber

1. Floral parts1. Floral parts

Advanced StateAdvanced StatePrimitive StatePrimitive StateCharacterCharacter


BesseyBessey’’ss dicta or rulesdicta or rules

•• similar tosimilar to foliar theoryfoliar theory of theof the

flowerflower

•• ““ Magnolia Magnolia = primitive= primitive”” ideaidea

•• general trend in angiospermsgeneral trend in angiosperms

has beenhas been reduction, loss, andreduction, loss, and

fusionfusion


BesseyBessey’’ss classification (classification (‘‘cactuscactus’’))

•• Bessey produced aBessey produced a

classification system based onclassification system based on

his ruleshis rules

•• ordersorders (-ales) of flowering(-ales) of flowering

plants attached showingplants attached showing

relationships and degree of relationships and degree of

primitive vs. advanced featuresprimitive vs. advanced features

•• orderorder RanalesRanales (( Magnolia Magnolia))

considered most primitiveconsidered most primitivepolypetalypolypetaly

hypogynyhypogyny

actinomorphicactinomorphic




BesseyBessey’’ss classification (classification (‘‘cactuscactus’’))

•• zygomorphy, fused petals,zygomorphy, fused petals,

and inferior ovary are foundand inferior ovary are found

further up the chartfurther up the chart

•• orderorder RanalesRanales (( Magnolia Magnolia))

considered most primitiveconsidered most primitive

sympetaly

epigynyactinomorphic

polypetaly

epigyny

actinomorphic

sympetaly

hypogyny

zygomorphic

polypetaly

hypogyny

actinomorphic


Contemporary classificationsContemporary classifications

•• most based onmost based on BesseyBessey’’ss

principlesprinciples

•• which characters stressed,which characters stressed,

though, varies (subjective)though, varies (subjective)

TakhtajanTakhtajan CronquistCronquist

ArmenArmen TakhtajanTakhtajan’’s ands and ArthurArthur

CronquistCronquist’’s are similar withs are similar with

subclassessubclasses (-idae) as the major(-idae) as the major

groupingsgroupings



•• most based on Besseymost based on Bessey’’ss

principlesprinciples

•• which characters stressed,which characters stressed,

though, varies (subjective)though, varies (subjective)TakhtajanTakhtajan CronquistCronquist

CronquistCronquist’’s best developed of thes best developed of the

contemporary classificationscontemporary classifications

based on morphologybased on morphology



•• Rolf DalhgrenRolf Dalhgren (d. 1987):(d. 1987):

Danish taxonomist whoDanish taxonomist who

emphasizedemphasized chemicalchemical featuresfeatures

DalhgrenDalhgren

•• Robert ThorneRobert Thorne (Rancho Santa(Rancho SantaAna Botanical Garden): stillAna Botanical Garden): still

modifying his morphologymodifying his morphology

based system using DNAbased system using DNA

evidenceevidence

ThorneThorne




Molecular classificationsMolecular classifications

•• the 1993 paper examining DNAthe 1993 paper examining DNA

of 500 genera of seed plantsof 500 genera of seed plants

revolutionized phylogeneticrevolutionized phylogenetic

classificationclassification



•• Angiosperm Phylogeny GroupAngiosperm Phylogeny Group

classificationclassification —— APGI (1998);APGI (1998);

APGII (2003) used inAPGII (2003) used in Plant Plant

SystematicsSystematics texttext

•• APGIIIAPGIII (2009)(2009) – – used in courseused in course



•• APGAPG uses DNA and a lot of uses DNA and a lot of

morphologymorphology

•• e.g., use of pollene.g., use of pollen

features to delimitfeatures to delimit

““eudicoteudicot”” – – the 3-poredthe 3-pored

pollen bearing floweringpollen bearing flowering

plantsplants


classificationclassification —— APGI (1998);APGI (1998);

APGII (2003) used inAPGII (2003) used in Plant Plant

SystematicsSystematics texttext

•• APGIIIAPGIII (2009)(2009) – – used in courseused in course




classificationclassification —— UW BotanyUW Botany

Gardens first garden based onGardens first garden based on

the APG system!the APG system!



Issues in GroupingIssues in Grouping

1. Convergence a problem with any system1. Convergence a problem with any system

•• repeated shifts torepeated shifts to wind pollinationwind pollination && reduced flowersreduced flowers



•• repeated shifts torepeated shifts to inferior ovariesinferior ovaries



•• repeated shifts torepeated shifts to corolla tubescorolla tubes• various trees that you will see in this coursevarious trees that you will see in this course


2.2. ““Tree ThinkingTree Thinking”” - what a phylogenetic tree is . . .- what a phylogenetic tree is . . .

R

R

R

rootedrooted rootedrooted

rootedrootedunrootedunrooted




2.2. ““Tree ThinkingTree Thinking”” - what a phylogenetic tree is- what a phylogenetic tree is notnot . . .. . .

FishFish NewtNewt LizardLizard MouseMouse HumanHuman

Is a newt more closely related to a fish than to a human?Is a newt more closely related to a fish than to a human?

NoNo! this is the ancestor of ! this is the ancestor of

human and newthuman and newt

Tip reading is ladder reading, incorrect!Tip reading is ladder reading, incorrect!

FishFish NewtNewtLizardLizardMouseMouseHumanHuman


2.2. ““Tree ThinkingTree Thinking”” - what a phylogenetic tree is- what a phylogenetic tree is notnot . . .. . .

XX XX XX XX

ancestor of human andancestor of human and

newtnewt


3. Named groups are3. Named groups are monophyleticmonophyletic (ancestors and all(ancestors and all

descendants)descendants)

= ancestor= ancestor


3. . . . vs.3. . . . vs. paraphyleticparaphyletic (not all descendants included - usually(not all descendants included - usually

because these are highly modified)because these are highly modified) - should these be allowed?- should these be allowed?


= excluded descendant= excluded descendant

= modifications= modifications




3. e.g.3. e.g. CaesalpinoidCaesalpinoid legumes arelegumes are paraphyleticparaphyletic

•• faboidfaboid (beans, peas)(beans, peas)

andand mimisoidmimisoid

(acacia, mimosa)(acacia, mimosa)

legumes are highlylegumes are highly

modifiedmodified

•• but descendedbut descended

from the commonfrom the common

ancestor of ancestor of

caesalpinoidscaesalpinoids


3. . . . vs.3. . . . vs. polyphyleticpolyphyletic (more than one ancestor - defined by(more than one ancestor - defined by

convergent feature)convergent feature) - these are avoided- these are avoided


= convergence= convergence


4. Not all monophyletic groups are named -4. Not all monophyletic groups are named - limited categorieslimited categories

available in ranked (Linnean) systemsavailable in ranked (Linnean) systems

= named group= named group

= not named group= not named group


5. Ranks are abitrary -5. Ranks are abitrary - but follow Linnean categories:but follow Linnean categories:

kingdom, phylum, class, order, family, genus, specieskingdom, phylum, class, order, family, genus, species

MagnoliophytaMagnoliophyta

PinophytaPinophyta

GnetophytaGnetophyta

CycadophytaCycadophyta

GinkgophytaGinkgophyta

GymnospermsGymnosperms= 4 phyla= 4 phyla




5. Ranks are abitrary -5. Ranks are abitrary - but follow Linnean categories:but follow Linnean categories:

kingdom, phylum, class, order, family, genus, specieskingdom, phylum, class, order, family, genus, species

MagnoliophytaMagnoliophyta

PinopsidaPinopsida

GnetopsidaGnetopsida

CycadopsidaCycadopsida

GinkgopsidaGinkgopsida

GymnospermsGymnosperms

= 4= 4 classesclasses in 1in 1

phylumphylum

PinophytaPinophyta

or . . .or . . .


6. International Code of 6. International Code of

Phylogenetic Nomenclature orPhylogenetic Nomenclature orPhyloCodePhyloCode (established 2004)(established 2004)

•• taxon based on phylogenytaxon based on phylogeny

(a(a ““cladeclade””) - rankless) - rankless

•• content of taxon specifiedcontent of taxon specified

by the phylogeny or treeby the phylogeny or tree

•• any clade can be namedany clade can be named

http://www.ohiou.edu/phylocode/http://www.ohiou.edu/phylocode/

International CodeInternational Code of of

NomenclatureNomenclature oror ““rankedranked”” //““LinneanLinnean”” systemsystem

vs.vs.

•• ranked taxon defined basedranked taxon defined based

on typeson types

•• content of defined taxon notcontent of defined taxon not

specified except for typespecified except for type

•• limited number of groups orlimited number of groups or

ranks can be namedranks can be named


•• in practice and informally,in practice and informally,

recent phylogeneticrecent phylogenetic

classifications have beenclassifications have been

using a hybrid of ranked andusing a hybrid of ranked andrankless groupingsrankless groupings

APG IIIAPG III

•• APGIII usesAPGIII uses ranksranks forfor

families and ordersfamilies and orders; informal; informal

rankless names for largerrankless names for larger

groupsgroups

04 Classification

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