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CH 20: Nonvascular Plants: Mosses, Liverworts, and Hornworts (Characters…
CH 20: Nonvascular Plants: Mosses, Liverworts, and Hornworts
Characters of Nonvascular Plants
Mosses, Liverworts, Hornworts
Spanish moss
Tillandsia usneoides flowering plant
pineapple family
not a true moss
club mosses
Lycophytes
not mosses
slimy bright green "mosses
Spirogyra
green algae
lichens
Bryonia
Alectoria
Usnea
reindeer moss
have leafy stems
Embryophytes
do not have vascular tissue
multicellular sporangia & gametangia
reproductive cells surrounded by sterile cells
not composed of filaments
terrestial & cuticle, stomata
life cycle w/ alternation heteromorphic generations
the gametophyte
larger, more prominent generation
more familiar
photosynthetic, perennial
haploid phase
collects mineral nutrients
spread rapidly by asexual reproduction
the sporophyte
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smaller, more temporary
very inconspicuous
produces very small
absorb minerals from gameteophytes
always remain attached
little photosynthesis
cannot support own growth/sporogenesis
never grow large
being small/simple
great selective advantage
mosses/liverworts
thrive in microhabitats
stone walls
fences
bare rock
https://www.thoughtco.com/non-vascular-plants-4126545
Division Hepatophyta: Liverworts
The Gametophyte Generation
hepatic gametophytes
thallose liverworts
gametophyte stage initiated
spores germinate
small temporary protonematal phase
liverwort protonemata
never extensive/ramified
as long lived as mosses
apical cell established
gametophore begins
antheridiophore
male gametophores of Marchantia
produce umbrella shaped outgrowth
archegoniophores
also stalked
apex set of radiating fingers
project upward
droop downward
leafy liverworts
gametophyte stage initiated
spores germinate
small temporary protonematal phase
liverwort protonemata
never extensive/ramified
as long lived as mosses
apical cell established
gametophore begins
resemble moss-thin leaves
slender stem
two rounded lobes
no midrib
no conducting tissue
three defined rows
prostate liverworts
shoot grows flat
against substrate
underside row of leaves is reduced
may be completely suppressed
could be replaced by rhizoids
The Sporophyte Generation
little variability
morphology is like mosses
liver sporophytes
calyptra-covered sporangium
is globose
while young
bright green
chlorophyllous
no stomata
sterile cells
much thinner outer layer
one cell thick
lacks columella
seta
extremely delicate
composed of clear, thin-walled cells
collapse quickly
Marchantiales
have no seta
a foot
https://study.com/academy/lesson/the-life-cycle-of-a-liverwort.html
Division Bryophyta: Mosses
The Sporophyte Generation
embryophytes, megagamete, zygote
small
megagametophytes
six cells other than eggs
synergids and antipodals
degenerate after egg fertilized
undergoes syngamy
offer little protection
offer little nourishment
zygote
nutrients supplied by grandparent generation
sporophyte
endosperm formation
supported by moss gametophytes
undergoes transverse division
basal cell
small, bulbous tissue (foot)
capsule
upper cell, expand
apical sporangium
4 more items...
outer layer of sterile cells
inner column sterile cells (columella)
bottom of archegonium
absorbs sugar, minerals, water
transfer cells, many species
Metabolism and Ecology
small size
lack of conducting tissues
vascular plants
tend to be large
bulk
protects from short term fluctuations
moisture availibility
air humidity
if air becomes dry
seed plant stems won't die
seed plant leaves won't die
The Gametophyte Generation
Morphoglogy
leafy stems (gameteophytes)
moss plants grow close
others more open/loose
Scouleria gameteophytes
grow as ribbons
submerged in rapid/flowing water
not homologous
Moss Gameteophytes
#
#
grow from apical meristem
contain apical cell
derivative cells subdivide
water conducted by capillary action
Water Transport
hydroids
innermost cortex
conduct water
dissolve minerals
elongated cells lost cytoplasm when mature
walls partially digested
leptoids
resemble sieve cells
interconnections w/ adjacent cells
lack nuclei at maturity
retain cytoplasm
rhizoids
small, multicellular, trichome-like
penetrate surface of substrate
only anchor stem
do not absorb water/minerals
lack chloroplasts
have reddish walls
Division Anthocerotophyta: Hornworts
The Gametophyte Generation
are always thin along edges
center become more than 4-5 cells thick
shaped like ribbon/heart
may grow outward
irregularly forming disk
upper surface may be smooth
but other may be thin
chlorophyllous lamellae grow upward
https://www.britannica.com/plant/hornwort
parenchymatous
brittle
rather succulent
does not tolerate drying
The Sporophyte Generation
have foot embedded in gametophore tissue
above foot is meristem
continuously produces new sporangium tissues
pushed upward
grow, differentiate, mature, and die
simultaneously being replaced
by more cells
from basal meristem
long, horn-like cylinder
1-2 cm long
Phaeoceros
Anthoceros
up to 12 cm in others
at the tip
mature and open
result of dehiscence
two linear apertures
stomata
has stomata
Phaeoceros
Anthoceros
no stomata
Dendroceros
Notothylos
Megaceros
no seta
no discrete sporangium
outer layer sterile cells
thick
up to six cells deep
chlorophyllous
spores
green, golden yellow, brown, black
when ready, will release
some species multicellular
Hornworts
small, inconspicuous thalloid
grow on moist soil
hidden by grasses/herbs
rarely inhabit tree trunks
or bare rocks
not often encounterd
100-150 named species
five or six genera
Anthoceros
Phaeoceros
eroded soil good site
resemble thalloid liverworts
hornworts never contain oil bodies
liverworts always have oil bodies
never independent
lack leptoids&hydroids
supports
