Bryophytes Flashcards
How long ago did bryophytes develop?
- 450 million years ago, around same time as amphibians
What does epiphytic mean?
- this means they can grow on structures like trees for mechanical support (but do not take nutrients)
What are rhizoids?
- produced by bryophytes, help break rock down into soil: makes bryophytes important in primary succession
What bryophytes initially evolve from green algae?
- to develop peroxisomes in order to combat photorespiration which was wasteful/toxic
What are some similarities between bryophytes and green algae?
- motile chlorophyll with developed grana, chlorophyll a and b, cellulose in cell wall, mitotic spindles remain during cytokinesis, phytochrome pigment (blue-green)
True or false: during evolution sporophytes become larger and less complex?
- False: sporophytes become larger and MORE complex
Describe the gametophytes, categories, branching, and shape of arechgonia and antheridium of the liverworts?
- gametophytes are unisexual: male or female can be produced by gametophytes
- antheridia: cups, archegonium: umbrella
–> dichotomously branched
–> gametophyte dominant generation
–> categories of liverworts defined by: complex thalloid or leafy thallus
Describe the vegetative structure of the liverworts
- thallus:
- haploid, dichotomously branched
- no stomata, vault tissue, roots
- has rhizoids to help hold it in place
Describe the key component of marchantia asexual and sexual
- asexual: simple fragmentation - gemma are produced in Gemma cups, dispersed by splashes of rain
- sexual: uses antheridisophores and archengoniosphores that arise on the male and female gametophytes
Describe the key components of the sporophyte of marchantiophytes/liverworts?
- calyptra: the parts of the gametophyte that surround the sporophyte
- the foot: attached it to the gametophyte
- spores and elaters
- seta: the body of the sporophyte
*NOTE: fertilization occurs within the archegonium
What are elaters for? Where are they found?
- they twist, used to disperse spores in marchantia (liverworts)
Describe sphagnidae
subgroup of the bryophyta (true mosses)
–> two forms: sphagnum (distinct red/brown capsule) and ambuchania
- typically found in bogs, 1-3% of the earth, made of two cells: large dead cells and narrow red or brown live cells
- good for: absorption, phenolic properties, source of fuel, store carbon, bog people!
What are the two types of cells which from sphangidae mosses?
- large dead cells
- narrow, red or brown living cells
What is are rhizoids?
rhizoids: a property of marchantiphyta (liverworts)
- breaks down rock to form soil to grow in
: replaces roots for non vascular plants
Describe granite mosses
andraeidae: grow in extreme conditions: mountainous, cold regions. sometimes on snow! (these are the exceptions to mosses which require warm moist environment: they are the only plants found growing in high altitude mountainous environments)
Describe bryidae and their lifecycle
- true mosses: have no true vascular tissue so instead have leptons and hydroids
- life cycle:
- saprophyte grows from gametophyte: saprophytes have a covering (calyptra) which covers the capsule growing on the seta: capsule has operculum and peristome
- these release spores which develop into protonema and then male and female gametophytes : gamete develops within female gametophyte and grows as young sporophyte again!
where does the zygote develop in bryidae? What does this mean for dependency? Further, how do sperm know where to swim?
- zygote forms in the archegonium, which means that sporophyte is completely dependent on gametocyte
- egg releases malic acid which is a chemical that attract sperm
How are spore dispersed in Bryophyta?
- the calyptra falls off, operculum bursts open and spores are revealed within the peristome
What are paraphyses?
- small sterile hairlike structures around reproductive organs of lower plants 9bryophytes, algae, fungi)
- function in protection and storing water around stem
- antheridia: larger cells, archegonium: smaller, closer
Describe hornworts (anthocerophyta)
- horn shaped sporophytes with stomata
- gametophytes are more horizontal than vertical
- some species N fixing
- called resurrecting plant due to heat shock proteins
What species is known as the ‘resurrecting plant’?
- hornworts: anthocerophyta
- have heat shock proteins: protect proteins in plant so they are dead but when given water come back to life: life period often quite short
What body type, thalloid or leafy, do Bryophyta have?
they have. leafy thallus
What body type, thalloid or leafy, do marchantiophyta have?
- they have both thalloid and leafy
What are Gemma cups?
- found in marchantiophyta, used in asexual reproduction for simple fragmentation:
- skip sporophyte stage, become new gametophytes
Describe the tracheids and vessel elements. Which plants have either? How do vessel elements undergo differentiation?
- tracheids ;kac perofratin plates, present in all vascular platns
- vessel elements: perforation plants, differnetiated/advanced, only in angiosperms
- vessel elements undergo differentiation through programmed cell death
What are the body shaped of the Bryophyta taxa?
Leafy
Describe leaf margins in bryophyte and marchantophyta
In mosses the leaf margins are smooth or toothed, and the leave spiral around the
stem. In liverworts, the leaf margins will be ragged, and there will be a set of small leaves on the
under surface against the stem.
Figure 5: Examples of Bryophyta, left, and Marchantiophyta, right under the microscope. Note
the leaf margins and the arrangement of leaves against/ around the stem.
Describe the appearance of sphagnum
droopy, pom poms on top
Describe the marchantiophyta sporophyte
- foot, seta, calyptra, elaters
describe the pellia sporangium (marchantiophyte)
round ball at top, many spores inside, seta and capsule on outside
What kind of spores are produced in the bryophytes
Homospores!
Describe the sphagnum sporophyte
- of the sphagnidae, droopy with pom pots on top!
- large round: has a foot, seta, and many spores within a moon crescent shaped sporangia inside
Describe the polytrichum capsule
- of the bryidae
- long, narrow, spores in outside, capsule: conducting strands (hydroids and leptoids) in the middle
Describe homospory and heterospory
- homospory: one type of spore produced, can result in male and female gametophytes or bisexual
- heterospory: two different spores produced from different sporangia: microspores and megaspores from microsporangia and megasporangia
