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Invasion of Land
Bryophytes
• Liverworts
• Hornworts
• Mosses
*[All have alteration of generations - gametophyte dominates]
Liverworts
• anteridiophore
• archegoniophore
*[Protects embryo]
Hornworts
• plus…
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Begin to see
clear evidence like spores that prove the initial invasion of land
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However, plants invaded land first then
animals
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• There are some sorts of aspects associated with invasion of land in terms of
the adaptability of the organism to survive on land
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Has an adaptive trait for being able
to survive on land
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High levels of oxygen which compete on the same
enzymes as carbon dioxide does
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Issue is when you look at this between charophytes and other
organism
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As a gas

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and as bicarbonate
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In air, going to see the greatest issue with
competition with oxygen
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The next trait is the archegonium and antheridium
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When you look at whats going on
there- you see the antheridium that holds the motile sperm
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The archegonium, same
deal
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Sperm
swims over and fertilize with the egg
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The sporophyte is diploid and will grow up in the
gametophyte embedded - they are protected
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Confers a
selective advantage associated with the organism
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All have diploid and haploid
multicellular gametophytes but in case of charm its the haploid that
dominates
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As you go into the vascular plants the gametophyte is much smaller and
the sporophyte is larger
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Gametic is diploid multicellular- vegetative is haploid
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Other people have argued that diploid is better because they can house more
mutations
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Transition from gametophyte domination to sporophyte domination now
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Archegonia is a method of protection
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Have a horn like
structure known as a sporophyte
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When you go up on land, you have to be careful about desiccating and
dying when water stops
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They have an epidermis that holds the skin
structure and every once in a while in there you have the cells that have a
core in the centre
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When
you have low water the mouth or stomates will close - on the surface of
the leaf
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• Mosses [leptoids and hydroids]- or the true bryophytes are by far
extraordinary dominant
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Have beginning
hints of vascular transport system
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Has three different
states- to maximize adaptability of the moss
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When they germinate they form a structure
known as a protonemata
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The next step is from the protonemata you will get bud formation
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Protonemata will
grow towards moisture so that it has maximal ability to survive long term
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This bud is
something else
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Water is important for survival but
needs light as well in order to photosynthesize
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Buds become
multicellular and become leafy
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That’s where photosynthesis will occur
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Get the formation of the archegonium and the
antheridium- fertilization occurs with the formation now of the
sporophyte
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• These mosses are dominant on the face of this planet and have been around
for around 400 million years or so and play a significant role in terms of
vegetative dominance overall and some of it is historical as well
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Because of the conditions that exist inside the bog due to mosses, it actually
is a good way to preserve things
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In this bog like environment- relatively low rates of water evaporation- water
stands for a period of time
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Don’t get
many decomposers in this side of the environment because of the
acidity- don’t get a large quantity of nitrogen present- nitrogen is required
for the growth of plants and can make amino acids and proteins so
animals like it as well
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2 examples are Drosera and Sarracenia Insectivorous- insect eating plants in order to
obtain the nitrogen
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Has trigger
hairs on the inside
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These
then are organisms that live effectively in bogs
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Sphagnum was used for wound dressing- the antimicrobial activity of the
moss would minimize infectivity, systemic infection and chance of death
prior to the discovery of antibiotics
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The initial concentration of
cO2 is very high
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The appearance of these
organisms on land has a huge impact on the atmosphere and the soil as
well

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