plants

What are bryophytes?
Bryophytes are the oldest land plants on earth, and have been around for 400 million years or more. Although small, they can be very conspicuous growing as extensive mats in woodland, as cushions on walls, rocks and tree trunks, and as pioneer colonists of disturbed habitats.
They comprise three main taxonomic groups: mosses (Bryophyta), liverworts (Marchantiophyta) and hornworts (Anthocerotophyta) which have evolved quite separately.Worldwide there are possibly 10,000 species of mosses, 7000 liverworts and 200 hornworts.
Most bryophytes have erect or creeping stems and tiny leaves, but hornworts and some liverworts have only a flat thallus and no leaves.
How do bryophytes live their lives?
Bryophytes have a two-stage life cycle (alternation of generations). The ‘gametophyte' generation is the green photosynthetic part (the familiar moss or liverwort plant) attached to the substrate by threads (rhizoids), and the ‘sporophyte' generation which consists of a stalk and capsule which are dependent on the gametophyte for support and nutrients. The capsule when ripe releases thousands of tiny spores. Sexual reproduction occurs on the gametophyte generation and requires water for fertilisation. Many bryophytes also produce ‘gemmae': tiny buds, discs or leaf fragments which spread the plants vegetatively.
Pteridophytes
Distribtion
A large group of ancient or primitive land plants with worldwide distribution, all continents except Antarctica and most islands, favouring moist temperate and tropical regions, they can be found in all but the most frigid and most arid environments. Free water is required for fertilization and the production of a new generation of plants. There are no marine species.
Notes
The 'Pteridophyta' is generally considered to be a biologically unnatural group but the use of the term persists, largely out of convenience and the need for a handle for the 'ferns and related plants'.
The pteridophytes are a collection of several major groups at the division or class level that rank alongside the Bryophyta (mosses and liverworts) and the Spermatophyta (seed-plants). There are 4 such groups, one of which are the true ferns, the remainder the fern allies:
• Psilotophyta (or Psilotopsida or Psilopsida)
o Psilotaceae
• Lycopodiophyta (or Lycopodiopsida or Lycopsida)
o Lycopodiaceae
o Selaginellaceae
o Isoetaceae)
• Equisetophyta (or Equisetopsida or Sphenopsida)
o Equisetaceae)
• Polypodiophyta (or Polypodiopsida or Filicopsida)
o Families of true ferns
Gymnosperms
Gymnosperms are a type of plant that reproduce by a seed that is not enclosed as with angiosperms who have seeds contained flowers. Many of these plants are conifers or cone bearing plants. Gymnosperms are found throughout the world. They have roots and stems. Their leaves are in the form of needles in conifers.
At the time of pollination, the pollen or male pollen grains fall among the cone scales until they fall on to the ovules. As the cone grows up, it gets bigger and the seeds that are created by the male pollen and female parts are seen. Most conifers are evergreens or always green and they do not shed their leaves as deciduous plants do but retain their needles for quite a while. When the needles fall off, they are quickly replaced.
Angiosperms
Angiosperms are flowering plants. Angiosperms are the biggest group in the plant kingdom. They have true roots, stems, leaves and flowers. They also have seeds.The seeds are formed when an egg or ovule is fertilized by pollen in the ovary. The ovary is within a flower. The flower contains the male and/or female parts of the plant. Fruits are frequently produced from these ripened ovaries.
Angiosperms are more highly evolved that the algae, mosses, fungi and ferns. Their advanced structures allow angiosperms to thrive on land. They have roots that hold the plant in place and take in needed minerals and water. They have leaves that are the major food makes for the plant. They have stems that hold the plants up and move the nutrients and water about the plant.
Angiosperms the primary food source for animals and provides oxygen for us to breathe. They provide lumber for buildings and other objects, fibers for clothes, are the basis for many drugs, etc…