Plant Diversity Exam 1

What are the 3 disciplines that compromise plant systematics?

taxonomy, phylogeny, and evolution

What are the 4 main goals of systematics?

Inventory Earth’s biota, nomenclature, logical classification, and demonstrate evolutionary implications of biodiversity

What are the goals of taxonomy?

Identify and name a species, and classify species groups

What are the advantages and disadvantages of common/vernacular names?

Advantages are they are descriptive, easy to remember, and accessible. The disadvantage is that one species can have multiple names or a name can be shared by multiple species, or it may be a misnomer

What are the advantages of the scientific naming system?

All species have a name, the uniform system avoids confusion, and it facilitates data retrieval

What is indicated by the parenthetical authority here?

That Linnaeus was the first to describe the species

What is indicated by the Michx. authority?

That Michx. has credit for reclassifying the binomial

Describe the type method in phylogeny

Every species name must be linked to a type specimen used to keep track of synonymous names and lessen confusion

Define Holotype

A type specimen dedicated by the describing author

Define Lectotype

Chosen later from the original material when no holotype was designated

Define Neotype

Chosen from non-original material when original material is lost or destroyed

Describe Syntype

Two or more specimens cited in the original description when no holotype was designated

Define Paratype

Additional specimens cited in the original description that aren’t the holotype

What is the type species for flowering plants?

Magnolia virginiana L.

What is the difference between a species name and a scientific name?

species names are binomial nomenclature, scientific names also include the authority

When do scientific name synonyms exist?

When a species is reclassified into a new genus

What are the 5 rules of botanical nomenclature?

1. Names are based on nomenclatural types 2. There is only 1 accepted name for a taxonomic group 3. Names must be treated as latin 4. rule of priority 5. Botanical nomenclature is independent from zoological nomenclature

What are the 3 main systems of classification?

Artificial, Natural, and Phylogenetic

Describe the two types of artificial classifications

1. Based on “essentialism”, organized by habit, which is growth form. Easy but it groups unrelated plants together 2. Herbalists organized by medicinal property

Define natural classification

Organized by suites of characters, such as flower or fruit structures

Contribution of Andrea Caesalpino in 1519-1603

First to organize plants based on the characteristics of their flowers and fruits

Contribution of John Ray 1628-1705

Used all parts of plants in classification, recognized difference between dicots and monocots

Contribution of Pierre Magnol

First to establish family-level classifications

What was Carolus Linnaeus plant classification system?

The sexual system, which is an artificial classification because he chose a priori characters based on workability

Contribution of de Jussieu

Most complete natural classification system through taxonomic gardens

Define phylogenetic classification started by Darwin

Grouped based on a common ancestor; genealogy + change

Describe the Engler - Prantl classification system

A natural classification with phylogenetic influence that started with simple flowers, assumed to be primitive, and progressed to more complex flowers

Contributions of Charles Bessey

Coined ancestral vs. derived characters that became the basis for phylogenetic classification

What did Charles Bessey assume was the ancestral state of flowers?

Numerous floral parts, no fusion, multiple lines of symmetry, and ovary below petals

What are the advantages of Linnaeus sexual system?

It was mechanically effective in that it was usable, predictable, expandable, and immutable

Define synapomorphy

Shared derived character

What are Bryophytes?

Seed-free nonvascular plants that arose in the Ordovician 445ma

What is the earliest evidence of land plants, from the Ordovician coastal plains?

Cryptospores, which were wind-dispersed with tough sporopollenin walls

What are the main challenges for a plant colonizing land?

Overcoming reliance on water for reproduction, preventing desiccation, conducting water, structural support, and anchoring

How did early land plants overcome the reliance on water for reproduction?

Sporopollenin walls and UV protective coatings on their spores

How did early plants avoid desiccation?

Developed a protective cuticle with stomata to avoid water loss and protect from UV and pathogens

How did early plants conduct water and nutrients?

By the Devonian, some had tracheids. Bryophytes had hydroids and leptoids

How did plants meet the need for structural support?

Mechanical support tissues like xylem and wood and the evolution of leaves due to less stem photosynthesis

What did early plants evolve for anchorage and nutrient uptake?

Bryophytes had rhizoids for anchorage only. Devonian plants evolved proto-roots, which lacked the root caps and branching of modern roots

What are the 3 phyla of Bryophytes?

Marchantiophyta (liverworts), Bryophyta (mosses), and Anthocerotophyta (hornworts)

Characteristics of Marchantiophyta

Thalloid (sheet-like) or leafy form, asexual reproduction via gemmae cups, and small short-lived sporophytes

Separate male and female gametophytes, where sporophytes hang beneath female “umbrella”; Texas common liverwort

Marchantia polymorpha

What is shown in this image? (Be able to draw this on test)

Alternation of generations in Bryophytes

Reproductive organs closed in protective involucres, spores released in tetrads; Texas balloonwart

Sphaerocarpos texanus

Characteristics of Bryophyta

Leafy form, Sporophyte has foot, seta, capsule, and peristome teeth

Pioneer moss, long red seta, hygroscopic (capsule twists with humidity); Texas bonfire moss

Funaria hygrometrica

Hyaline cells for large water capacity, ecosystem engineers because they release acids and dead material forms peat; Peat moss

Sphagnum spp.

Cosmopolitan species tolerant of desiccation and pollution, first moss to colonize disturbed areas, form small silver-green cushions; Silver moss

Bryum argenteum

Characteristics of Anthocerotophyta

Thalloid form, unique horn-shaped sporophyte that is larger and more independent than in other Bryophytes

Cosmopolitan species, tolerant of dry and polluted soils, pioneer species, low rosette-like gametophyte with horn-like sporophytes; Field hornwort

Anthoceros agrestis

Thin, smooth thallus, large chloroplasts, sporophytes long and capable of continuous growth, tolerant of disturbed soils; Smooth hornwort

Phaeoceros laevis

The first vascular plant in the fossil record, stomata and vessels but no leaves or roots

Cooksonia barrandei

When did vascular plants begin to rapidly diversify?

Late Devonian

Characteristics of Lycopodiophyta

Microphyll leaves, sporangia in strobili, and Heterospory

Characteristics of Lycopodiaceae - club mosses

terete (cylindrical) strobili, evergreen, and homosporous

Characteristics of Selaginellaceae - spike mosses

Tropical, 4-ranked leaves, and Heterosporous

Characteristic of Isoetaceae - quillworts

Heterosporous with basal sporangia

3 Families of Lycophytes in Texas

Lycopodiaceae, Selaginellaceae, and Isoetaceae

Characteristics of Polypodiophyta - Ferns & Horsetails

Reproduce via spores, megaphyll leaves

Define Vernation

The arrangement of folded leaves in a bud

Define indusium

flap-like structure in ferns that protects the sori

Define annulus

The row of cells on the sporangium of ferns that dry and shrink causing the spore to be released

Fern with marginal sori, one of the most widespread vascular plants, bracken family

Dennstaedtiaceae

Often growing on rocky outcrops, maidenhair fern family

Pteridaceae

Diverse group, usually in woodlands, sori along veins, woodfern family

Dryopteridaceae

Sori in pea-like sacks at the base of petioles, water-clover family

Marsileaceae

Floating aquatic, reduced ferns, symbiotic relationship with nitrogen-fixing bacteria, mosquito fern family

Azollaceae

What two species are possbily the world’s longest living tree?

Pinus longaeva or Fitzroya cupressoides

What species includes with the world’s tallest tree and the world’s largest tree (by width)?

Sequoia sempervirens

What is the latin meaning of “Gymnosperm”?

Naked seed

What are 2 advantages of wind dispersal, as seen in Gymnosperms? What is one disadvantage?

Don’t need water for reproduction, disperse farther. Successful pollination is chance-based

What are the advantages of seeds?

Survive in drier environments, provide a protective seed coat, and supply nutrients allowing dormancy

When were the Gymnosperms the most dominant flora and how do they compare today?

They were dominant in the Mesozoic but remain mostly in temperate zones or high latitudes today where it is cool and dry

Define dioecious

separate male and female plants

Characteristics of Cycads

Dioecious, insect-pollinated, multiflagellated motile sperm, and coralloid roots to host nitrogen-fixing cyanobacteria

Why are 70% of extant cycads endangered or vulnerable?

Over-collection, habitat loss, and a slow life cycle

Characteristics of Ginkgo

Only only living species, fan-shaped leaves, deciduous, dioecious, fleshy fruits, and multiflagellated motile sperm

Characteristics of Gnetales

Only Gymnosperms with vessel elements, Ephedra and Gnetum have insect pollination

What are the 4 extant groups of Gymnosperms

Cycads, Ginkgos, Gnetales, and Conifers

Characteristics of Conifers

Mostly trees, evergreen, needle-or-scale-like leaves, and woody cones

Scale-like leaves, only deciduous conifer, monoecious, produced “knees” for support and gas exchange, rot-resistant hardwood “the wood eternal”

Taxodium distichum

Tree whose males produce pollen clouds that cause ‘cedar fever’ in winter, drought tolerant, grows in limestone soils, not fire tolerant

Juniperus ashei

Large tree, reddish peeling bark, berry-like cones, range expansion due to fire suppression

Juniperus virginiana

Multi-stemmed small tree, distinctive red berry-like cones, resprouts after fires

Juniperus pinchotii

Long needle-like leaves in fascicles of 3, reduced range due to heavy exploitation, fire-resistant bark, habitat for red-cockaded woodpecker, dense wood “heart pine”

Pinus palustris

Short leaves in fascicles of 2 or 3, bark with resin pockets, resprouts after fire, important timber species, reddish-brown cones

Pinus echinata

Medium-length leaves in fascicles of 2 or 3, leaves clustered into “brooms” at the end of branches, glossy, prickly cones, orange-brown bark, popular timber plantation species, less fire-resistant

Pinus elliottii

Medium-length leaves in fascicles of 3, prickly cones, bark furrowed with age, fast-growing, good for timber and pulpwood

Pinus taeda

What are the 3 traits used to distinguish trees in the family Pinaceae?

Number of needles per fascicle, needle length, and cone size and color

What are the theories for why angiosperms seem to appear and diversify so suddenly in the fossil record?

They originated in alpine regions that don’t result in fossils, they evolved on now-lost islands, or they diversified in response to flower-visiting insects

What is Neocomian?

The earliest angiosperm fossil showing single-pored pollen

What is shown by the early Cretaceous leaf fossils of angiosperms?

Diverse venation patterns indicating rapid morphological and ecological diversification

Magnoliids were once seen as representatives of how primitive flowers looked. This is not accurate. According to the fossil record, what did the earliest known flowering plants look like?

aquatic or semi-aquatic plants with simple, petal-less flowers, and few floral organs

Based on phylogenetic reconstruction, what did the earliest flowers look like?

Bisexual, undifferentiated perianth, three whorls, insect-pollinated

Where did angiosperms arise?

Australasia in tropical regions along wet, lowland, or marginal habitats

From what lineage did angiosperms arise?

no living Gymnosperm group, most likely from the extinct Bennettitales lineage

What key innovations led to angiosperms being so successful?

Vessel elements for efficient water transport, mycorrhizal associations for nutrient uptake, genome polyploidy for genetic flexibility and rapid diversification, co-evolution with pollinators, flowers and fruits

Why are flowers the key innovation for angiosperm diversification?

They allow them to survive at low population densities, pollinators facilitate outcrossing, allows seeds to disperse far from their parents, and promote coevolutionary feedback loops

What is the latin meaning of “Angiosperm”

seed in vessel

What are the 4 defining features of angiosperms

Flowers, reduction of gametophyte stage, double fertilization, and vessel elements in xylem