BOTANY 400 - Lecture Exam 1

Phylogeny

• Pattern of Evolution

• All organisms in a taxa share a common ancestor.

• Used to find where a taxa originated.

Biosystematics

• Process of Evolution

• How, when, and where did a speciation event occur?

• Amount of Genetic Variation

Goals of Systematics

• Inventory Earth’s Biota

• Create Nomenclature for Identification & Communication

• Create an Orderly & Logical Sequence of Classification

• Demonstrate Evolutionary Implications of Biodiversity

Inventorying Earth’s Biota

• 1.9 × 10⁶ Species Discovered & Described

• Impossible to Estimate Total Number of Species

• Temperate Flora Inventory is Nearly Complete

• Tropical Flora Inventory is very open due to having many more species.

  • More endangered species as many are endemic to small areas.

• Barcode DNA to form Phylogenetic Trees

Nomenclature

• Used for Identification & Communication

  • Easier if plants have one name.

• Dichotomous Keys & Apps like iNaturalist

• Words & Vocabulary

• Important for Other Disciplines

Orderly & Logical Sequence of Classification

• Relates organisms with one another in a framework.

• Aids in Information-Retrieval as in an Herbarium or Website

• Type Species

Type Species

The species or specimen that a name is permanently attached to in the case of a taxonomic split or revision.

Demonstrating Evolutionary Implications of Biodiversity

• Detect Evolution at Work

• Understand Evolutionary Pathways

• Identify Origin of Both Ancient & Recent Diversity

• Morphological & Molecular Characteristics

• Tree of Genealogy, Phylogeny, & Life

• Looks at Processes & Patterns

The Muséum National d’Historie Naturelle

• Largest Herbarium in the World

• Contains Approximately 8.9 Million Preserved Plant and Fungi Specimens

• Located in Paris, France

• “Plant” of the Day #1

Algae to Angiosperms

• Largest Evolutionary Radiation of Plants

• Adaptations to Life on Land & Being Non-Motile

  • No Swimming Gametes

• Successive Rounds of Speciation & Extinction

• Set the stage for development of land-based ecosystems with fungi & animals.

• Researched through Fossils

Bryan Atkinson

• Paleobotanist & Dogwood Systematist

• Studies Fossils of Flowering Plants

  • Focused on Plants in Antarctica

• Contributed Much to Knowledge of Early Plant Evolution

• Botanist Spotlight #1

Angiosperms

• Flowering Plants

• Phylum Magnoliophyta

• Majority of Plant Diversity

Fungi

• Not Plants

• Evolutionarily Closer Related to Animals

Green Algae

• Lineage Charales

• Thought to be closest relative to embryophytes.

Embryophytes

Land Plants

The First Land Plants

• First Evidence of Land Life from 460 Million Years Ago

• Microfossils of Spores

• Similar to Bryophytes like Modern-Day Liverworts

Bryophyta

• Mosses, Hornworts, & Liverworts

• Non-Vascular

• Earliest Land Plants

• Gametophyte Dominant

• 16000 Species in 3 Separate Lineages

  • Non-Taxonomic Group

Rhynia

• Extinct Vascular Plant

• Seen in Early Devonian Period

  • About 400 Million Years Ago

• One of the First Vascular Plants

• 20cm Tall with No Roots or Leaves

• Primitive Vascular Tissue

• First Known Tracheophyte

Lycopodiophyta

• Club Mosses

  • Not True Mosses

• 1150 Species in 3 Familes

• Sporophyte Dominant

• Vascular Tissue

• Free Sporing

• Microphylls

• Sister Lineage to All Other Land Plants

Polypodiophyta

• Ferns

• Immense Variation in Habit & Habitats

• Spores Stored in Sporangia

• Require more Systematic Research, especially in Tropics

• Includes Horsetails & Whisk Ferns

Horsetails

• Unusual Group of Ferns

• 15 Species in Genus Equisetum

• Vascular Plants with Reduced Leaves & Terminal Sporangia

Whisk Ferns

• Unusual Group of Ferns

• 6 Species in 2 Genera

• Leafless Vascular Plants with Green Stems & Lateral Sporangia

The First Seed Plants

• Fern-Like Plants

• Found in Late Devonian

  • About 390 to 360 Million Years Ago

• Produced Naked Seeds with Embryos in a Covering

• Formed Much of Today’s Coal

Gymnosperms

• First Found in Permian Period

  • About 286 to 245 Million Years Ago

• Big Trees with Net-Veined Leaves

• Bear Naked Seeds derived from Female Gametophyte

• Form Pollen derived from Male Gametophyte

• 870 Species in Pinophyta

• Often Divided into 4 Phyla

  • Conifers, Cycads, Gingko, & Gnetophytes

Archaefructus

• First Known Flowering Plant

• Found in Very Early Cretaceous

  • About 146 to 65 Million Years Ago

• Underdeveloped Flowers

Magnoliophyta

• Phylum of Angiosperms

• 275,000+ Species

  • Potentially 400,000 Species

• Seed Plants with Seeds encased in Ovary

• Key Innovation of Flowers

  • Resulted in Adaptive Radiation

• Previously Divided into Classes Dicots & Monocots

• High Diversity with Very Large Size-Range

Eucalyptus regnans

An Angiosperm over 100 Meters Tall

Wolffia microscopica

An Angiosperm less than 1 Millimeter Long

Amorphophallus titanum

The Angiosperm with the Largest Inflorescence

Corypha Palms

The Angiosperm with the Largest Number of Flowers

Rafflesia arnoldii

The Angiosperm with the Largest Flower up to 1 Meter Across & 20 Pounds

Importance of Flowers

• Unlike Anything Else in Other Plants

• Extremely Variable

• Co-Evolved with Animals

• Used in Describing & Identifying Species

• Herbarium Specimens must include Related/Derived Features

• Basis of Angiosperm Classification

Flower Evolution

• Highly Modified, Determinate, & Specialized Shoot of Stem & Leaves

• Modified Stem with Compressed Internodes

• Modified Leaves in 4 Distinct Whorls with Various Functions Determined by Genes

  • ABC Model: Different Combinations of Expressed Genes result in Different Whorls

ABC Model

• Different Combinations of Expressed Genes (Genes A, B, & C) result in Different Whorls of a Flower

• Varies Amongst Taxa

• General Model: A = Sepals, AB = Petals, BC = Stamens, C = Carpels

Chelsea Specht

• Zingiberales Systematist

• Studies Genetic Basis for Floral Evolution

• Professor of School of Integrative Biology at Cornell

• Botanist Spotlight #2

Inflorescence

A Cluster of Flowers on a Larger Branch

Peduncle

Floral Stalk & Stem Supporting the Flower

Pedicel

The Stalk of a Single Flower in an Inflorescence

Receptacle

Modified Floral Stem & Base holding all Parts of Flower Together

Sepal

Outer/First Whorl of Protective & Generally Green Leaves

Calyx (CA)

Collective Term for the Sepals

Petal

Second Whorl of Typically Brightly Colored Leaves that attract Pollinators

Corolla (CO)

Collective Term for the Petals

Perianth (P)

Collective Term for both the Sepals & Petals

Tepals

Term for Similar Petals & Sepals or if One Set is Reduced

Stamen

Male Structure of Flower comprising of Filament & Anther

Androecium (A)

Collective Term for the Stamens meaning “House of Males”

Filament

Slender Stalk of Stamen that supports the Anther

Anther

Fertile Portion of Stamen composed of Sacs that dehisces to release Pollen Grains

Pollen Grain

Male Gametophyte of Angiosperms that forms Pollen Tube

Nectaries

Part often near Base of Stamens that produces Nectar Reward for Pollinators

Pistil

Flask-shaped, Female Sructure(s) comprising of 3 Main Parts and made up of One or More Carpel(s)

Gynoecium (G)

Collective Term for the Pistils/Carpels meaning “House of Females”

Stigma

Part of Pistil on Top of Style that Receives & Recognizes Pollen

Style

Slender Stalk of Pistil that Pollen Tubes pass through to reach Eggs in Ovules in Ovary

Ovary

Base of Pistil that contains Ovules & matures into Fruit with Seeds

Ovules

Fertile Portions of Pistil that contain Embryo Sac & develop into Seeds after Fertilization

Embryo Sac

Female Gametophyte of Angiosperms

Pollination Biology

• Study of Pollen, its Transfer to the Stigma, and Movement Down the Style

• Pollen Grain forms Pollen Tube

• Sperms travel down Pollen Tube to reach Ovules

Simple Pistil or Unicarpellate Gynoecium

Pistil with One Carpel

Apocarpic Pistils

Multiple Non-Fused Carpels

• One Pistil for Each Carpel

• Two or More Pistils

Syncarpic Pistil

Multiple Fused Carpels

• Multiple Carpels per Pistil

• Styles may be Separate or Fused

Carpel

Modified Folded “Leaf” with Ovules

Stigmatic Lobe

Result of Multiple Carpel in Fused Style

Placentation Types

Arrangement of Ovules

• Marginal

• Axile

• Parietal

• Free-Central

• Basal

Marginal Placentation

Arrangement of Ovules along Seam of Pistil that’s found in Almost All Simple or Apocarpic Pistils

Axile Placentation

Arrangement of Ovules along Central Wall of Pistil that’s found in Some Syncarpic Pistils

Parietal Placentation

Arrangment of Ovules along Outer Walls of Pistil that’s found in Some Syncarpic Pistils

Free-Central Placentation

Arrangement of Ovules in Middle of Pistil with No Central Walls that’s found in a Few Syncarpic Pistils

Basal Placentation

Arrangement of Ovules at Bottom of Pistil that’s found in Some Pistils of All Types

Merosity

Numerical Plan of Flowers & Arrangement of Perianth

Perianth Spiraled

Perianth Arrangement that’s Common in Early Angiosperms

Perianth 5-Merous

Perianth Arrangement that’s Common in Eudicots

Perianth 4-Merous

Perianth Arrangement that’s Occasional in Eudicots

Perianth 3-Merous

Perianth Arrangement that’s Common in Monocots & Some Early Diverging Angiosperms

Symmetry Plan

• Arrangement of Perianth

• Important in Pollination

• Radially = Actinomorphic

• Bilaterally = Zygomorphic

Actinomorphic

Flowers that are Radially Symmetrical

Zygomorphic

Flowers that are Bilaterally Symmetrical

• Petal serves as Landing Pad for Pollinators

Connation

Fusion of Floral Parts from the Same Whorl

• Syncarpic Pistil, Staminal Tube, Corolla Tube

Adnation

Fusion of Floral Parts from Different Whorls

• Simple: Stamens fused on Inner Surface of Petals

• Complex: Sepals, Petals, & Stamens fuse to form Hypanthium

Hypanthium

Adnation of Calyx, Corolla, & Androecium

Ovary Superior

• Placement of Ovary above Attachment of Other Parts

  • Separate from Rest of Flower

• Line Below G in Floral Formula

• Flower is Hypogynous or Perigynous

Ovary Inferior

• Placement of Ovary below Attachment of Other Parts

  • Fused to Other Floral Parts

• Line Above G in Floral Formula

• Flower is Epigynous, Hypanthium often Present

Flower Hypogynous

Placement of Calyx, Corolla, & Androecium under Ovary

• Ovary Superior

• No Hypanthium

Flower Perigynous

Placement of Calyx, Corolla, & Androecium on Rim of Hypanthium

• Ovary Superior

• Hypanthium Present

Purpose of Nomenclature

• Identify & Name Species

• Classify or Place Species in Groups

• Aim to have Only One Correct & Stable Name per Species/Taxa

Advantages of Common Names

• More Well-Known to Common People

• Easy to Learn & Remember

• Often Descriptive

• Cultural Origins

Disadvantages of Common Names

• Often Regionally Different

• One Species may have Many Different Ones

• Multiple Species may have the Same One

• Can be Misleading & Taxonomically Incorrect

• Many Plants lack One

Nymphaea alba

A Plant with 245 Common Names

Scientific Names

• Uniform System to Avoid Confusion

• Easier to Retrieve Information

• Follows International Code of Nomenclature

• Can be Descriptive

• Often named after Discoverers, Partners, Fictional Characters or Things, Presidents, & Celebrities

Polynomials

Full Latin Phrases originally used as Scientific Names

Genera

Plural of Genus

Specific Epithet or Trivial Name

• Originally the Shorthand Name used by Lienaus

  • Species Plantarum published in 1753

• Italicized

• Not Capitalized

• Ending Agrees with “Gender” of Genus Name

Authority

• Name of Botanist that described the Species

• Often Abbreviated

• Not Italicized

• Placed after Specific Epithet

• If species renamed or moved to new genus, first to use epithet is placed in parentheses before name of first to use binomial.

Synonyms

Duplicate Names for Same Species or Taxa

Type Method

Every Species (or Higher Taxa) Name must be linked to Specific Herbarium “Type” Specimen

• First Named Specimen of Species, Genus, Family, Etc.

• If Clade or Group is Split, the Clade with the Type Specimen Keeps its Name(s)

Holotype

The Particular Specimen that Automatically fixes Application of a Name & is used as a Base Reference

____type

Other Specimens to Replace Holotype when it’s Lost or Unknown

Steps of Naming a New Species (READ)

• Find Untaken & Never-Before Published Binomial

  • Unaccepted but Published Names Unusable

• Make Type Specimen & Deposit It in Herbarium

• Description of New Species, typically in Latin or English

• Publish in Peer Review Journal made Visible

  • May be Published & Valid, but not Automatically Accepted or Good

Phylocode

• Alternative Nomenclatural Code

• Enacted in Paris in 2004

• Rankless: Only Phylogenetic Lineages or Clades named Above Species Level

  • No Genus, Family, Binomials, Etc.