plant diversity exam 1

what is taxonomy?

the science of classifying and naming plants

main goals of taxonomy:

identification, nomenclature, classification

how do the three components of systematics inform and depend on each other?

what are the four primary goals of systematics?

1. Inventory of Earth’s Biota

2. Identification and Communication: Nomenclature

3. Orderly, Logical Sequence of Classification

4. Demonstrate Evolutionary Implications of Biodiversity

advantages of common names:

• descriptive, colorful

• easy to remember

• only names for most people

disadvantages of common names:

• one species can have many common names

• one common name = same for more than one species

• names can be confusing

• most plants dont have a common name

why do we use scientific names?

• all species need names

• uniform system on naming = avoid confusion

• facilitates information - retrieval

who developed the binomial system of nomenclature?

carolus linnaeus

species name

* species: binomial name (Genus and epithet)

what are species synonyms and why do they exist?

• duplicate name

• discovered by two different people around the same time

what is the type method and what is the purpose of a type species?

• every species name must be linked to a herbarium specimen

• type species sets “the standard” of the species = holotype

Process for naming a species

• find a binomial not taken (Genus + epithet)

• make type specimen and deposit at herbarium

• latin / english description of new species

• publish in journal or visible paper product

• THIS MAKES IT VALID not directly accepted

epithets

• descriptive term

• label that associates species w a certain group

scientific name

* scientific: species name + authority

authority

the name of the person or persons who provided the binomial for the species

process of renaming

* put OG authority into parenthesis

5 basic rules of botanical nomenclature

1. name based on nomenclatural types (genus type etc)

2. only one accepted name for a taxonomic group

3. names must be treated as latin but a lot of latitude

4. nomenclature based on rule priority

5. independant from zoological nomenclature

rule of priority

1st published binomial for a species in a genus is the accepted name ( start 1753 )

artificial classification system

• habitat is an essential character to naming (essentialism)

• logical, efficient, easy, but rigid

artificial classification groups

• theophrastus - 372-287 BC

• herbalists-physicians - alphabetical or medicinal property for classification 15-16 centuries

natural classification system

• 1580-1800

• lots of new plants coming in

• Andrea Caesalpino

  • focus on flowers and fruits (reproductive parts)

• John Ray

  • all parts of plant shoudl be used to classify

  • dicots and monocots

• Pierre Magnol

  • families

• Carolus Linnaeus

  • created the sexual system

Sexual Systems

• carolus linnaeus

• workable “natural” classification system

• backward step to artificial

• Species Plantarum (systema sexuale)

  • classification based on reproductive features

  • selective and features chosen a priori simply on workability

Species Plantarum

• arranged as systema sexuale

• 1st level: number of stamens

• 2nd level: number of pistils

• intense criticism ( johan siegesbeck )

• more concerned w mechanics (usable, predictable…) = lots of issues

why was the sexual system an advancement and a step back?

• considered backwards bc it was artificial (mechanics of reproductive parts?)

• an advancement bc focused on reproductive parts

Natural Classifications 1760-1880

• linnaeus did good w cataloging but unrelated plants were being grouped

• taxonomist reconsidered purpose of classification = look at older natural ideas

• de Jussieu family created most complete natural classification

  • natural system came from taxonomic gardens

  • replanting @ Trianon Garden by grouping most similar looking

  • published Genera Plaantarum

Phylogenetic Classifications

• 1859 to publication of Origin of Species

• to darwin natural meant that two species looked similar because they shared a features from a common ancestor

  • must include: genealogy + amount of change (similarity)

  • descent w modification = evolution

  • “common ancestry is a fact - the outcome is a phylogenetic tree

• Ernst Haeckle publish the first TREE OF LIFE

Engler-Prantl classification system (phylogentic)

• 1915 their system had phylogenetic flavor w simple plants listed first then more complex plants

• standard in the early 20th century

• simple (salix) = primitive

  • amentiderae = primitive

Charles Bessey Phylogenetic System

* classification of angiosperms w ideas on ancestral vs derived characters
* looked at the ancestral vs derived state of many pllant characteristics
* bessey’s dicta = basis of his system
* formed the basis for all subsequent modern systems

Besseys dicta

1. floral parts -

   1. all present (ancestral state)

   2. loss of parts (derived state)

2. Floral fusion

   1. parts separate

   2. parts fused

3. floral symmetry

   1. actinomorphy

   2. zygomorphy

4. ovary position

   1. hypogynous

   2. epigynous

molecular classifications

• AGP (angiosperm phylogeny group) uses DNA to establish relationships and morphology to ID groups

• goal of groups is to include common ancestor and descents

tips

* extant individual in a population

nodes

* inferred ancestors

branches

* unique history of linages

topology

* overall branching pattern of tree

clade or monophyletic group

* a group of tips w node (common ancestor) and all of the descents

goal of modern taxonomic ?

* for all generas/families/orders etc to be monophyletic

sisters

* tips or clades that share a common ancestor that is not shared by others

synapomorphy

* a trait derived from the most recent common ancestor of a clade and shared by all taxa in the clade

paraphyletic

• some but not all descendants of a common ancestor are included

• need revision

polyphyletic

• species derived from more than one ancestor

• need revision

Challenges of terrestrialization

• desiccation

• UV radiation

• temperature fluctuation

• novel pathogens

• pressure change

Adaptations during movement to land (???)

develop a symbiotic relationship

Mycorrhizae

• symbiosis between plant roots and fungi

• represents ancestral state for land plants

how did symbioses with bacteria and fungi help plants overcome these challenges?

• mycorrhizae: between plant roots and fungi

  • help obtain nutrients in roots from the soil

  • help with water uptake

• bacteria:

  • nitrogen fixing

  • alter soil temp. and moisture = impact heterotrophic respiration

how do non-vascular plants differ from vascular plants?

* non-vascular: lack true vascular tissue = xylem and phloem

what is meant by “vascular plant” and how does this differ from bryophytes with hydroids and leptoids?

• Bryophytes don’t have vascular tissues ( xylem ) to help them transport water ( get thru leaves instead)

• hydroids: water and mineral conducting specialized cells

• leptoids: sugar-conducting specialize cells

Can vascular plants undergo desiccation?

no, vascular system and waxy cuticle prevent it.

Why is water so fundamental to bryophytes?

* since bryophytes do not have a structure to keep and transport water, they must live near water so they can use it when they need it

alternation-of-generation life cycle (non-vascular)

1. haploid produces antheridia (male) and archegonia (female) bits.

   1. these produce gametes via mitosis

2. two come together = fertilization of ovum via biflagellate sperm

3. fertilization results in diploid zygote that develops into a sporophyte

   1. sporophyte is dependent on gametophyte

4. sporophytes produce haploid spores through meiosis

5. spores disperse and germinate into a protonema (baby gametophyte)

gametophyte

* the body

sporophytes

* the tips w them sporangium capsules

Anthocerotophyta

• the hornworts

• lack seta

• simple thallus

• lack gemmae

• lack water conducting cells

• stomata on both gametophyte and sporophyte (don’t close)

• 215 species

Thallus

* plant body lacking roots, stems, or leaves
* complex thallus: containing multiple strata, with marked differentiation of tissues
* simple thallu: undifferentiated thallus

Leafy

* terete and bearing leaf-like appendages

rhizoids

* filamentous structures that anchor the plant
* can be used in some species for water uptake via capillary action

hydroids

* water conducting cells. not in hornworts

leptoids

• sugar conducting cells

• only in moss family polytrichaceae

capsule

* contains sporangium (produces spores)

Operculum

* in mosses, the lid that blocks the capsule mouth

calyptra

* a little hat (absent in hornworts)

seta

• sporophyte stalk

• absent in hornworts

Marchantiophyta

• the liveworts

• nicholas marchant

• gametophyte thalloid or leafy

• lack stomata

• 7300 species

• noble taxa = marchantia = very common = model system

Bryophyta

• the mosses

• gametophyte a leafy shoot

• stomata on sporophyte capsule

• complex sporophyte capsule

Bryophyta (Body Plans)

• Acrocarpous

  • upright w terminal sporangia (all upright)

  • unbranched

• Pleurocarpous

  • produce their sporangia on short lateral branches or buds

  • prostrate - forming freely branches mats (sporophytes upright rest sideways)

• complex sporophyte capsule

  • peristome = a ring of teeth surrounding the mouth of the capsule (teeth move in response to changes in humidity)

Sphagnum (Bryophytas Notable Taxas)

* Major component of peatlands
* fuel producation // horticulture
* 3% of global land surface
* peatlands = contain up to 44% of all soil carbon

Dawsonia superba (Bryophytas Notable Taxas)

• big boys

• tallest self-supporting bryophhyte

Physcomitrella patens (Bryophytas Notable Taxas)

• first seedless plant to have genome sequenced

• model system for evolution / genomics

Super cute (Bryophytas Notable Taxas)

• Ulota

• Macromitrium

homosporous

* one kind of spore is produced

heterosporous

* different spores are produced

Microspore

* give rise to male gametophytes

Megaspore

* give rise to the female gametophytes

megaphylls

* complex leaves with branches veins

microphylls

* small, simple, one veined leaves

Circinate vernation

* vernation is the arrangement of folded leaves in a bud, forming a crozier or fiddlehead

indusium

* falp-like structure that protects the sorus

Sori (plural), Sorus (singular)

* Sporangia borne on the margin or the lower surface of the leaf

double fertilization

* the sperm cell has two nuclei - one fertilizes the ovule, the other fertilizes two polar nuclei

Tracheid

* a type of water-conducting cell in xylem which lacks perforations in the cell wall

Whorl

* a whorl arrangement of leaves, sepals, petals, stamens, or carpels that radiate from a single point and wrap around the stem/stalk

Sporangia

* an enclosure in which spores are formed

Strobilus

• a reproductive system of gymnosperms

• hold the sporangia that produce the spores

• cone like structure (kinda light brown / orange)

terete

* cylindrical // rounded

prostrate

* laying down

dichotomous branching

* branching by forking in airs, can be irregular or equal

sporophyte

• the spore-producing individual or phase in the life cycle of a plant having alternation of generations

• a diploid phase in the life cycle

• MEIOSIS produces spores diploid

sporophyll

gametophyte

• stage of sexual reproduction process that produces HAPLOID gametes

• MITOSIS produces egg and sperm haploid

antheridium

• male sex organs

• diploid side

archegonium

• female sex organs

• diploid

spiral arrangment

* leaves are opposite and alternate

monomorphic

* leaves on flower plant = leaves on non-flowering plant

dimorphic

* plant organs that appear in two distinct forms or shapes on the same plant or in closely related species

sheath

* a protective covering on the lower part of the stem

Blade

* leafy part

phylogeny w lycophypts, ferns, gymnosperms, angiosperms

when were lycophytes dominate? How does this relate to reproductive traits

• carbonniferous period

• very wet period

• water needed for fertilization of lycopod gametophytes

• they had no protective coating

what is darwin’s abominable mystery?

* the origin and rise of angiosperms

when did angiosperm begin to arise in the geological record?

jurassic / early cretaceous

are angiosperms relatively recent?

yes relatively recent