Plant Ecology > Mosses > Flashcards

Mosses Flashcards

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1
Q

Phyla of Bryophytes (refers to all non-vascular plants)

A
  • Marchantiophyta (Liverworts)
  • Anthocerophyta (Hornworts)
  • Bryophyta (Mosses)
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2
Q

Monophyletic

A

Linear group of phyla

- The 3 bryophyte phyla divereged independently early in plant evolution before the origin of vascular plants

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3
Q

What is a cladogram?

A

A diagram that shows ancestral relations without a time frame between taxa

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4
Q

Which bryophyta phyla are the most reasonable models of early plants?

A

Liverworts and hornworts

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5
Q

Which bryophyte phyla are the most closely related to vascular plants?

A

Mosses

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6
Q

Charophytes

A

Division of green algae most closely related to byrophytes

- Aquatic algae

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7
Q

Bryophyte evolution

A
  • Bryophytes were the first plants for 100 million years that terrestrial communities existed
  • Then vegetation began to take on a taller profile for better access to light, therefore vascular tissue developed
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8
Q

What does a gametophyte consist of?

A
  • Gamete producing structures, the gametophores
  • Root-hair-like rhizodes
  • Haploid
  • Photosynthetic
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9
Q

Moss reproduction

A
  • Gametes produced in Gametangia
  • Dioecious with separate male and female gametophores
  • Female produces a vase-shaped Archegonium with a single egg
  • Male produces elongated antheridia with many flagellated sperm
  • Sperm need at least a small amount of water to disperse and ‘swim’ to female
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10
Q

What is the dominant form in a moss?

A

Gametophyte, haploid is dominant over diploid sporophyte

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11
Q

Sporophyte

A
  • Diploid, less dominant, moss structure that is only present part of the year
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12
Q

Homosporous

A

Bryophytes have spores that are all the same size

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13
Q

How do mosses grow?

A

Spores germinate in favourable habitat and grow by mitosis into masses of branched 1 cell thick filaments called protonemata

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14
Q

Mitosis

A

Produces more haploid

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15
Q

Meiosis

A

Produces spores

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16
Q

What is a protonemata?

A

Mass of green, branched, one-cell thick filaments that produce meristems when sufficient resources are available

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17
Q

What is a meristem?

A

Region of active cell division that generate gametophytes

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18
Q

How do sperm find the archegonia?

A

Chemotaxis

- they follow chemical attractants

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19
Q

What is the Zygote?

A

Young sporophyte that is retained and nourished by the parent gametophyte 9placental nutritive cells transport materials from parent to embryos)

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20
Q

Liverwort and Hornwort reproduction?

A

Simple sporophytes that consist of a short stalk (Seta) bearing round sporangia which contain the developing spores and have a nutritive foot embedded in the gametophyte tissues
- Seta is not elongated, protected inside

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21
Q

What are Rhizoids?

A

Multicellular filaments that anchor bryophytes

  • Not composed of tissues
  • Not photosynthetic
  • No specialized conducting cells
  • No primary role in water and mineral absorption
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22
Q

What 2 features make the sporophyte?

A
  • Seta (Stalk)

- Sporangium (holds spores)

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23
Q

Why are moss leaves so thin?

A

Being one cell thick situates all cells close to water and dissolved minerals

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24
Q

How is water and nutrient transport accomplished in gametophores?

A

By external transport

- sometimes by costas

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25
What is a Costa?
A nerve of specialized cells that runs lengthwise on a gametophyte leaf. - One costa can be a midrib - Can contain specialized cells that are not structural - Primitive tissue to transport water (Hydroids) - Analagous to a nerve, but do not call it a nerve!
26
What is a Hydroid?
Specialized cell that can conduct water within gametophyte - not the same as tracheid of vascular plants - non-structural
27
What are Leptoids?
Specialized cells that conduct organic compounds (minerals and Carbs from photosynthesis - not the same as tracheid of vascular plants - non-structural
28
What are Lamina?
Leaf blade cells that provide structure and are continuous on either side of the guide cells
29
What are guide cells?
Noticeably larger cells that are continuous with the cells that make up the rest of the leaf blade (lamina) - May be part of costa
30
Seta?
Term for the stem of a sporophyte that bears the bishops cap (sporangium) and the stem of the moss gametophyte - Do not call it a stem!
31
What do most stems consist of?
Concentric layers of: - Central cylinder of water conducting hydroids and nutrient conducting leptoids - Undifferentiated parenchyma cells - Supportive cellulotic stereid cells
32
Parenchyma
Basic cell in a plant - Early tissue appearing on 1st terrestrial plants - Undifferentiated cells
33
Why are most bryophytes so small?
Lack supportive tissues - Some family in NZ can grow really big though! - Show extreme examples of very small to quite large even in the same evolutionary family
34
Why are bryophyte leaves and stems not considered true?
They lack lignin-coated vascular cells - Lack the wax that is common protective feature on vascular plants - Vascular plants have a stomata for gas exchange on vascular leaves
35
Why are moss leaves so thin?
- Lack a cuticle and are only one cell thick to enhance water and mineral absorption from moist environment
36
What are the 2 growth habits of mosses?
- Ascocarpus | - Pleurocarpus
37
Ascocarpus
Mosses with erect growth form and apical sporophytes
38
Pleurocarpus
Decumbent Mosses or feather-like with lateral sporophytes that are not produced on the meristomatic tip
39
Perichaetium?
Whirl of leaves around the archegonium which will eventually produce the sporophyte
40
Capsule
Sporangium
41
What is special about Hair-cap mosses?
They have more complex leaves with ridges (lamellae) to enhance absorption of sunlight and increase photosynthesis - The ridges are coated with cuticle
42
What does a moss sporophyte consist of?
- Foot - Seta (elongated stalk) - Sporangium (capsule)
43
What does the Foot of the sporophyte do?
Gathers nutrients and water from the parent gametophyte via transfer cells
44
What does the Stalk of the sporophyte do?
Conducts materials gathered in the foot to the capsule
45
Why is the Seta elongate in most mosses?
So that the capsule can be elevated to enhance spore dispersal
46
Where does meiosis occur?
In the moss capsule (sporangium) | - Can generate over 50 million spores
47
Calyptra
Bishops Cap produced by all masses - Protective cap of gametophyte tissue on immature capsule - Haploid - Lost when capsule is ready to release spores
48
Peristome?
Upper part of capsule that can be specialized for gradual spore release - Under the calyptra and revealed when calyptra falls off - May have peristome teeth
49
Embryo
Diploid structure
50
Sphagnum
Peat moss - Abundant and widespread - Peatlands: High-latitude boreal wetland - Important carbon reservoir stabilizing atmospheric CO2 levels - Absorbent, comfortable, and antimicrobial so Historically used as diapers and antiseptic wound dressings - Harvested today as soil conditioner and packing material for plant roots (b/c they hold a lot of water in 'dead' cells) - Burned as blocks of fuel
51
Peat
- Extensive deposits of undecayed organic material formed from sphagnum, a wetland moss - Sphagnum is genus - Peat is product
52
Peat Bog
Wet region dominated by sphagnum moss
53
Why does peat moss not decay?
Does not readily decay due to resistant phenolic compounds and acidic secretions that inhibit bacterial activity
54
What is the growth form of sphagnum?
Rosette form
55
Hyaline
Clear, see-through cells | - LargeDead cells of sphagnum surrounded by smaller living photosynthetic cells
56
Sphagnum hold lots of water, why?
- Hyaline dead cells fill up like a cistern (only sphagnum does this) - These cells give the leaf a lot of structure - Cells have pores - Cross walls of dead cells give structure and hold it even when dry
57
Rithet's Bog
- Sphagnum Bog - Present water table can support sphagnum growth - Must transplant peat sphagnum to raise water table and hold onto water, not forest sphagnum - Need to remove shore pine (log to prevent further terrestrialization) and surface muck from shore pine needles an bark (produces non-wetland soil)
58
Restoration Study for Rithet's Bog
Before-After-Control-Impact - Split plots - Paired control Treatment: plots planted with sphagnum, with muck removal, and without Control with no muck removal or planting And all replicated - 2 controls: spatial (paired), and temporal (before/after impact assessments, need 5 years of data at least to get temporal control) - Other possible treatments include different depths of surface removal, or different combinations of peat moss species
59
Spatial Control
Paired plots beside each other, one treated, one without (control)
60
Temporal Control
- Time - Before and after data collected - Needs at least 5 years
61
Rithet's Bog study comparisons
With Spatial and Temporal controls - Pairwise btwn treated and untreated plots - Pairwise before and after - Track difference btwn pairs - Get trend data, may fluctuate some before treatment
Plant Ecology
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