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Algae
Mosses
Liverworts
Algae
- Algae were the first
proper plants
to evolve.
- Green algae are
the ancestors of all of today's land plants.
- They are very simple cellular plants,
with no roots, stems or flowers.
- While most are found in water bodies, salt
and fresh, the notorious blue green algae
forming blooms where nutrient loads are high.
- Others are found
on land where conditions are moist.
- Small forms grow as parasites below
the `skin' (the cuticle) of rainforest
leaves.
Mosses
- Represent an evolutionary step up from
algae.
- They have no roots and no system of woody
vessels which allow more advanced plants to grow tall.
- As the first land plants, mosses probably created
the first forests, mini-ecosystems just 5cm or so high.
- They achieve this impressive height simply by
packing themselves tightly together.
- The sex life of mosses resembles the complicated
system of alternate generations found in algae.
- Mosses keep the next generation at home, whereas
algal male and female cells meet by swimming freely through the water.
- O-moss cells are attached firmly to the parent
plant.
- When they have been fertilised by free-swimming
male cells they grow into spore-filled capsules on the end of long
stalks.
- These capsules eventually open to release the
spores which are blown away to grow into new moss plants.
- In some respects, this tendency to retain
the female egg on the parent plant resembles the habit of later plants, such
as cycads, conifers and flowering plants, to do the same.
- Perhaps it represents a step along the
evolutionary way.
Additional Mosses Information
Liverworts
- Liverworts are very similar to
mosses.
- However, where the pointed `leaves' of mosses
are arranged in spirals on the stems, liverworts have rounded (liver-shaped)
`leaves' which grow flat in double rows.
Courtesy of:
Environmental Protection Agency, Cairns.
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