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nonvascular plants: mosses, liverworts, and hornworts # (Anthocerotophyta:…
nonvascular plants: mosses, liverworts, and hornworts
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Bryophyta: Mosses
the gametophyte generation
ubiquitous
perennial
occuring in all parts of the world
in almost every environment
water transport
leptoids
resemble sieve cells
lack nuclei
retain cytoplasm
elongated
majority of mosses lack hydroids and leptoids
water conducted through capillary action along exterior stems
form narrow spaces
act as capillary channels
leaves/ stems very small
rhizoids
locateed at base of stem
small/ multicellular
penetrate substrate surface
only anchor system
reddish walls
lack chloroplasts
dont absorb water/ minerals
hydroids
innermost cortex cells
conduct water/ dissolved minerals
no cytoplasm
elongated cells
end walls partially digested
morphology
gametophores
leafy stems
development
sends out long chlorophyllous cell
undergoes mitosis
produces branched system of similar cells
protonema
resembles green algae
numerous small chloroplasts
entire network
begins when spore germinates
reproduction
gametophore
all mosses oogamous
produces gamerangia
the sporophyte generation
zygote of moss
undergoes transverse division
basal cell develops into small bulbous tissue
called the foot
interface w/ gametophore
absorbs, sugars, minerals and water from gametophore
upper cell grow by cell division
expansion into a simple apical sporangium
called the capsule
operculum
caplike lid
apex of sporangium
peristome teeth
1 more item...
seta
narrow stalk
between foot and sporangium
metabolism and energy
2 critical factors
lack of conducting tissues
small size
several mechanisms compensate
for inability of mosses to retain wate
grow in permanently moist microhabitats
tolerant of desiccation
desiccated mosses resistant to high/low temperature
and intense UV light
Anthocerotophyta: Hornworts
the sporocyte generation
no seta or discrete sporangium
foot embedded in gametophore
meristem just above the foot
produces new sporangium tissues
the gametophyte generation
or grow irregularly forming a disk
parenchymatous
succulent but brittle
lives less than 1 year
after fertilization divides longitudinally
winter annuals
may be shaped like a ribbon or heart
hidden by grasses/ herbs
grow on moist soil
small inconspicuous thalloid plants
superficially resemble thalloid liverworts
hepatophyta: liverworts
small plants
some species greatly resemble mosses
the gametophyte generation
divided into 2 basic groups
thallose liverworts
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flat ribbon like
body
aka thallus
air pores
no guard cells
cannot be closed
no stomata
or heart shaped/ bilaterally symmetrical
growth of gametophore begins
bisexual
antheridia
archegonia
or unisex depending on species
archegoniophores
apex of radiating fingers
antheridiophore
umbrella shaped outgrowth
male reproductive structure
leafy liverworts
gametophore resembles moss
two rounded lobes
no midrib
the sporophyte generation
basic morphology like that of mosses
most liverwort sporophytes:
seta
clear thin walls
collapse quickly
extremely delicate
calyptra covered sporangium
elators
spring shaped walls
uncoil pushing spores out
single elongate cells
foot
little variability exists
concepts
plants are divided into:
vascular cryptograms
vascular but no seeds
ferns
scouring rushes
clubmosses
spermatophytes
has vascular tissue and seeds
gymnosperms
angiosperms
cyads
nonvascular plants
no vascular tissue or seeds
liverworts
hornworts
mosses
characteristics of nonvascular plants
embryophytes
multicellular
surrounded by layers of sterile cells
bodies = true parenchyma
almost exclusively terrestrial
many have stomata
cuticle over much of their body
gametangia
sporangia
no vascular tissue
heteromorphic generations
sporophyt and gametophyte differ structurally
this whole chapter
look alike
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umbrella
fingers
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