plant systematics

JJA Obico, InstructorDepartment of Biology

U i it f th Phili i M ilUniversity of the Philippines Manila

A science that includes traditional A science that includes traditional taxonomy and phylogeny

GOAL:Phylogenetic reconstructionPhylogenetic reconstruction- evolutionary history of life

Major parts of systematics that includes Major parts of systematics that includes four components

A DescriptionA. DescriptionB. ClassificationC NomenclatureC. NomenclatureD. Identification

Taxon- subjects under study; any group of organismsof organisms

Assignment of features or attributes to a Assignment of features or attributes to a taxonCharactersCharacter states- two or more forms of charactersExample: Example: • petal color: yellow, blue• Leaf shapes: lanceolate, ovatep

Tools for communicationCategorizing and delimiting the attributes

f tof a taxon

a statement of its characters which thus a statement of its characters, which thus constitutes the definition of the taxon

Taxonomic characters• Characters contributing to the description• Characters contributing to the description

Including Cassuvieae (Cassuviaceae) R.Br., Spodiaceae (Spodiadaceae) Hassk., Spondiaceae(Spondiadaceae) Kunth(Spondiadaceae) Kunth

Excluding Blepharocaryaceae, Julianaceae, Pistaciaceae, PodoaceaeTrees, or shrubs. Plants non-succulent. Leaves nearly always alternate (opposite in Bouea);

simple, or compound; when compound, ternate, or pinnate; exstipulate.Plants hermaphrodite, or monoecious, or dioecious, or gynodioecious, or

polygamomonoecious.p ygFlowers in panicles. The terminal inflorescence unit racemose. Flowers typically 5 merous.Perianth with distinct calyx and corolla, or sepaline. Calyx basally gamosepalous.Androecial members free of the perianth; when coherent 1 adelphous (the filaments

sometimes basally connate). Stamens (1–)5–10(–12).Gynoecium 1–3–5(–6) carpelled. The pistil 1–5 celled. Gynoecium syncarpous; semicarpous

( l ) i t l i i ( ll ) tl i f i O (rarely), or synovarious, or synstylovarious; superior (usually), or partly inferior. Ovary 1–5 locular. Stigmas non-papillate. Placentation when bi- or plurilocular basal. Ovules in the single cavity when unilocular, 1; apotropous; anatropous; unitegmic, or bitegmic; crassinucellate.

Fruit when dry indehiscent; a drupe. Seeds non-endospermic.CC3.Widespread in the tropics, also Mediterranean, E. Asia, America.Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Rutiflorae; Sapindales. APG

(1998) Eudicot; core Eudicot; Rosid; Eurosid II; Sapindales. Species 600. Genera about 70.Including commercially important fruits — cashew-nut (Anacardium, and the fleshy

peduncle, ‘cashew-apple’), mango (Mangifera), Jamaica plum, hog-plum, imbup , pp ), g ( g ), J p , g p ,(Spondias). Resins, oils and lacquers from Toxicodendron.

Arrangement of taxa into some type of Arrangement of taxa into some type of orderSystem for cataloguing and expressing System for cataloguing and expressing relationships between taxaGrouping and RankingGrouping and Ranking

RANK TAXA___________Kindgom PlantaeKindgom Plantae

Division MagnoliophytaClass Liliopsida (monocots)p ( )

Order ArecalesFamily ArecaceaeGenus Cocos

Species Cocos nucifera

Primary ranks- ICBNSome ranks have particular ending/suffixSome ranks have particular ending/suffixRanks are hierarchical

PheneticPhenetic- classification based on overall similaritiessimilarities- common to everyone

Phylogeneticclassification based on evolutionary - classification based on evolutionary

history or pattern of descent

Can be arbitrary Can be arbitrary, e.g., classify these:

Represented in the form of a cladogram/ Represented in the form of a cladogram/ phylogenetic treeCladogramCladogram• Lines- lineage or clades; denote descent• Branching- divergence from a common ancestorBranching divergence from a common ancestor

Evolution recognized as a change from pre-existing character state(ancestral) to pre existing character state(ancestral) to a new (derived) character state

All of life is interconnected by All of life is interconnected by

TAXA descentdescent

A B C D E F

TIME

lineage or clade

TIME

Cladogram or Phylogenetic TreeCladogram or Phylogenetic Tree

A B C D E F TAXA

TIME

speciation

Cladogram or Phylogenetic Tree

CladisticsCladisticsMethodology of inferring the pattern of evolutionary history of a group of evolutionary history of a group of organisms using apomorphic characters

Ancestral characterPleisiomorphy- Pleisiomorphy

Derived character- Apomorphy- Apomorphy

Apomorphies the result of evolutionApomorphies - the result of evolution.

Taxa sharing apomorphies underwent Taxa sharing apomorphies underwent same evolutionary history,should be grouped togethershould be grouped together.

A B C D E F

TAXA

Apomorphiesf B&C

Apomorphyfor taxon D

for taxa B&C

TIME

Apomorphyfor taxa B-F

Cladogram or Phylogenetic Tree

Common ancestry

TAXA

A B C D E F

TIME

common ancestor (of taxon D, E, & F)

Cl d Ph l ti T

common ancestor (of taxon A & taxa B-F)

Cladogram or Phylogenetic Tree

Recognized group in phylogeneticRecognized group in phylogeneticsystematicsConsisting of a common ancestor plus all Consisting of a common ancestor plus all of its descendantsSequential listing of monophyletic groupSequential listing of monophyletic group- serve as a phylogenetic classification schemescheme

A B C D E F TAXA

monophyletic group

TIME

t

common ancestor (of taxon A & taxa B-F)

common ancestor (of taxon D, E, & F)

Cladogram or Phylogenetic Tree

Consisting of a common ancestor but not Consisting of a common ancestor but not all descendants of that common ancestor

Two or more separate groups each with a separate common ancestor

A B C D E F TAXA

TIME

common ancestor (of taxon A & taxa B-F)

common ancestor (of taxon D, E, & F)

Cladogram or Phylogenetic Tree

A B C D E FTAXA

A B C D E F

TIME

common ancestor ( f t A & t B F)

common ancestor (of taxon D, E, & F)

Cladogram or Phylogenetic Tree

(of taxon A & taxa B-F)

Formal naming of taxa according to Formal naming of taxa according to standardized systemInternational Code of Botanical International Code of Botanical NomenclatureScientific names (Latin)Scientific names (Latin)A taxon will bear ONLY ONE scientific namenameBinomial system of naming

Pterocarpus indicaPterocarpus indicaUnderscored or italicizedgeneric name: always capitalizedgeneric name: always capitalizedspecific epithet: not capitalizedSpecies name: binomialSpecies name: binomialBinomial nomenclature• Carolus Linnaeus • Carolus Linnaeus

1 Universal1. Universal-morning glory and woodbineyellow bellyellow bell

2 common names are not consistent2. common names are not consistent- two common names

one common name refers to more than - one common name refers to more than one species

3 Tells nothing about the rank3. Tells nothing about the rankRose

4 Not all organisms have common name4. Not all organisms have common name

Principle I. (INDEPENDENCE)Principle I. (INDEPENDENCE)

Principle II. (TYPE)

Principle III. (PRIORITY)

P i i l IV (CORRECT NAME)Principle IV. (CORRECT NAME)

Principle V. (LATINIZED)c p e V ( N )

Principle VI. (RETROACTIVE)

HolotypeHolotype• upon which a name is based, originally used or

designated at the time of publicationdesignated at the time of publicationIsotype• duplicate of holotype (same time, same person, p yp ( , p ,

same population)Lectotype• selected from original material to serve as the

type when no holotype was designated, or the holotype is missingholotype is missing

NeotypeNeotype• Derived from non-original material to serve as

the typeSyntype• Any specimen cited in the original work when a

holotype was not designatedholotype was not designated• Can be one of 2 or more specimens that were

designated as typesParatype• Specimen cited but not a holotype, isotype or

syntypesyntype

Associating an unknown taxon with a Associating an unknown taxon with a known oneTaxonomic KeyTaxonomic Key• Consists of sequentially choosing among a list of

possibilities until the possibilities are narrowed possibilities until the possibilities are narrowed down to one

Dichotomous keyDichotomous key• Series of two contrasting statements• CoupletsCouplets• Lead- each statement in the couplet

1 Stamens fused at base into a tube ........……....... Dichelostemma

1' Stamens not fused at base into a tube

2 Fertile stamens 3 ......................................................Brodiaea :

2' Fertile stamens 6

3 Stamens strongly winged at base ...............….......Bloomeria

3' Stamens not strongly winged at base .......….........Muilla

1 Ovary inferiory

2 Ovules two per carpel .............................. Dilatris

2’ Ovules five per carpel ............................. Lachnanthes

1’ Ovary superior

3 Perianth zygomorphic

4 Nectaries present .................................... Wachendorfia

4’ Nectaries absent ..................................... Barberetta

3’ Perianth actinomorphic .............................. Xiphidium

Polyclave keyPolyclave key• Consists of a list of numerous character states

whereby the user selects all of states of that match the specimen

• Implemented by a computer algorithmAdvantages:Advantages:1. Still useful if specimen lacks one or

more type of datayp2. ID will be narrowed down at least if not

ID

Written description• Floras- Flora of Manila (E. Merrill)

Listing of plant taxa of a given region usu. accompanied by keys and descriptionp y y p

• MonographDetailed taxonomy study of all species of a taxonomic groupgroup

Specimen Comparison• Herbarium- repository of preserved plant

collectionsImage comparisonExpert DeterminationExpert Determination