Land Plants: Bryophyte Diversity Flashcards
What is polytomy?
a node on a phylogeny where more than two lineages descend from a single ancestral lineage
What is the stage in a plant life cycle that is not present in a green alga life cycle?
multicellular sporophyte (2n) stage
Are bryophytes vascular or non-vascular plants?
non-vascular plants
What is the relation of Bryophytes to algae and vascular plants?
considered transitional between the two
What conditions do Bryophytes live in?
moist locations (no vascular tissues or root system), require water for reproduction
found on all continents
How does fertilization and dispersal work for Bryophytes?
water (sperm) and air (spores)
What are synapomorphies?
a derived or changed character state shared by two or more lineages in a particular clade. an indicator of common ancestry
What are 3 synapomorphies of bryophytes and vascular plants?
antheridia (sperm-producing) and archegonia (egg producing) with sterile protective layer
retention of zygote and multicellular embryo within female gametophyte
multicellular, diploid sporophyte
How did alteration of generations create differences between Bryophytes and Vascular plants?
bryophytes - gametophyte dominant, free-living
sporophyte smaller, dependent on gametophyte
vascular plants - sporophyte dominant, free-living
gametophyte smaller, most are dependent on sporophyte
What are the 3 adaptations for bryophytes life on land?
thin thallus (main body) - facilitates uptake of water and CO2
surface pores (analogous to stomata) - gas exchange
cuticles (waxy surface layer to prevent water loss)
What is the antheridia?
sperm
what is the archegonia?
egg
how does sexual reproduction work in Bryophytes?
after fertilization zygote (2n) remains in archegonium, nutrition from female gametophyte
sporophyte (2n) - dependent, attached to female gametophyte
Sporangium - produces haploid spores
What are the 3 phyla (or lineages) of Bryophytes?
Hepatophyta - liverworts
Anthocerophyta - hornworts
Bryophyta - mosses
Where are Hepatophyta (liverworts) found?
in moist habitats, growing on tree trunks and in moist soil
roughly 8000 species
describe the structure of a liverwort (hepatophyta)?
‘leafy’ thallus (gametophyte) only 10-30 cells thick
upper surface photosynthetic - contains pores for gas exchange (analogous to stomata)
What is a spieces of Hepatophyta?
Marchantia
Marchantia have elaters, what are these?
elongate, helically arranged hydroscopic cells (absorb moisture), aid in spore dispersal
What type of reproduction do Marchantia carry out and how?
asexual reproduction via gemmae formation - the gemmae can transform into new gametophyte plants
Where are features of Antherocerophyta (Hornworts)?
gametophyte - thallus, rosette
cavities inhabited by cyanobacteria - nitrogen fixation
roughly 100 species
What are the 3 major groups of Bryophyta (mosses)?
Sphagnidae - Sphagnum (peat mosses)
Andreaeidae - granite mosses
Bryidae - ‘true’ mosses
Where is Sphagnum (species of moss) found?
in bogs and marshes
What is a feature of Sphagnum making it unique for peat bogs?
holds 20x dry weight in water
What is industry can Sphagnum also be used in? as what?
horticulture - soil additive, planting medium, packing material for roots
How can Sphagnum be used in medicine?
decay resistant phenolic compounds giving it antisepctic properties (wound dressing) (probs WW1)
WHat does the decay resistant phenolic compounds of Sphagnum do to soil?
increases acidity of soil - release H+ ions (bogs pH < 4)
What is the significance of Sphagnum peat bogs (size and potential effect on planet)?
makes up only 2-3% of total land surface
- large carbon sinks
- warmer temps could lead to increased rates of decomposition leading to more CO2 in atmosphere
What is a species of true mosses?
Polytrichum (common haircap moss)
What are features of Polytrichum (Common Haircap Moss)?
evergreen perennial plant up to 1.5ft tall, stems of individual plants are erect to sprawling
found in moist habitats
Describe the life cycle of mosses
spores produced and mature forming female and male gametophytes
egg is produced in archegonia, sperm is produced in antheridia
fertilization occurs and zygote (2n) forms
zygote becomes an embryo
embryo develops into a sporophyte
after maturation of sporophyte meiosis occurs and cycle begins again
