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. |
